A. Escapa, M. San-Martín, A. Morán

Frontiers in Energy Research • 2014

Globally, large amounts of electrical energy are spent every year for domestic wastewater (dWW) treatment. In the future, energy prices are expected to rise as the demand for energy resources increases and fossil fuel reserves become depleted. By using appropriate technologies, the potential chemical energy contained in the organic compounds present in dWWs might help to improve the energy and economic balance of dWW treatment plants. Bioelectrochemical Systems (BESs) in general and microbial electrolysis cells (MECs) in particular represent an emerging technology capable of harvesting part of this energy. This study offers an overview of the potential of using MEC technology in dWW treatment plants (dWWTPs) to reduce the energy bill. It begins with a brief account of the basics of BESs, followed by an examination of how MECs can be integrated in dWW treatment plants (dWWTPs), identifying scaling-up bottlenecks and estimating potential energy savings. A simplified analysis showed that the use of MEC technology may help to reduce up to ~20% the energy consumption in a conventional dWWTP. The study concludes with a discussion of the future perspectives of MEC technology for dWW treatment. The growing rates of municipal water and wastewater treatment markets in Europe offer excellent business prospects and it is expected that the first generation of MECs could be ready within 1-4 years. However, before MEC technology may achieve practical implementation in dWWTPs, it needs not only to overcome important techno-economic challenges, but also to compete with other energy-producing technologies.

I. Vasiliadou, A. Berná, Carlos Manchon et al.

Frontiers in Energy Research • 2018

Domestic and industrial wastewaters contain organic substrates and nutrients that can be recovered instead of being dissipated by emerging efficient technologies. The aim of this study was to promote bio-hydrogen production and carbon fixation using a mixed culture of purple phototrophic bacteria (PPB) that use infrared radiation in presence or absence of an electrode as electron donor. In order to evaluate the hydrogen production under electrode-free conditions, batch experiments were conducted using different nitrogen (NH4Cl, Na-glutamate, N2 gas) and carbon sources (malic-, butyric-, acetic- acids) under various COD:N ratios. Results suggested that the efficiency of PPB to produce biogenic H2 was highly dependent on the substrates used. The maximum hydrogen production (H2_max, 423 mLH2/L) and production rate (H2_rate, 2.71 mLH2/Lh) were achieved using malic acid and Na-glutamate at a COD:N ratio of 100:15. Under these optimum conditions, a significant fixation of nitrogen in form of single-cell proteins (874.4 mg/L) was also detected. Under bio-electrochemical conditions using a H-cell bio-electrochemical device, the PPB were grown planktonic in the bio-cathode chamber with the optimum substrate ratio of malic acid and Na-glutamate. A redox potential of -0.5 V (vs Ag/AgCl) under bio-electrochemical conditions produced comparable amounts of bio-hydrogen but significantly negligible traces of CO2 as compared to the biological system (11.8 mLCO2/L). This suggests that PPB can interact with the cathode to extract electrons for further CO2 re-fixation (coming from the TCA cycle) into the Calvin cycle, thereby improving the C usage. It has also been observed during cyclic voltammograms that a redox potential of -0.8 V favours considerably the electrons consumption by the PPB culture, suggesting that the PPB can use these electrons to increase the biohydrogen production. These results are expected to prove the feasibility of stimulating PPB through bio-electrochemical processes in the production of H2 from wastewater resources, which is a field of special novelty and still unexplored.

N'dah Joel Koffi, S. Okabe

SSRN Electronic Journal • 2022

Performances of anodic ammonia oxidation have been investigated for various bioelectrochemical systems at a wide range of poised anodic potentials in the literature. The effect of poised cathodic potential on ammonium nitrogen (NH4+-N) and total nitrogen (TN, sum of NH4+-N, NO2--N, and NO3--N) removal from domestic wastewater by single chamber air-cathode microbial fuel cells (MFCs) was investigated. Poising the air-cathode potential at + 0.7 V vs. SHE significantly increased current generation (from 11 ± 1 mA to 22.8 ± 5 mA) and oxygen permeation into the MFC through the air-cathode (from 75.4 ± 1.2 g-O2/m3/d to 151 ± 3.7 g-O2/m3/d), which consequently resulted in a high NH4+-N removal rate of 150 ± 13 g-NH4+-N/m3/d and TN removal rate of 63 ± 16 g-TN/m3/d. These high NH4+-N and TN removal rates could be attributed to the enhancement of dual respiratory pathways: the electrode-assisted anodic and aerobic NH4+ oxidation.

Marshall D. McDaniel, L. Tiemann, A. S. Grandy

Ecological Applications • 2014

Our increasing dependence on a small number of agricultural crops, such as corn, is leading to reductions in agricultural biodiversity. Reductions in the number of crops in rotation or the replacement of rotations by monocultures are responsible for this loss of biodiversity. The belowground implications of simplifying agricultural plant communities remain unresolved; however, agroecosystem sustainability will be severely compromised if reductions in biodiversity reduce soil C and N concentrations, alter microbial communities, and degrade soil ecosystem functions as reported in natural communities. We conducted a meta-analysis of 122 studies to examine crop rotation effects on total soil C and N concentrations, and the faster cycling microbial biomass C and N pools that play key roles in soil nutrient cycling and physical processes such as aggregate formation. We specifically examined how rotation crop type and management practices influence C and N dynamics in different climates and soil types. We found that adding one or more crops in rotation to a monoculture increased total soil C by 3.6% and total N by 5.3%, but when rotations included a cover crop (i.e., crops that are not harvested but produced to enrich the soil and capture inorganic N), total C increased by 8.5% and total N 12.8%. Rotations substantially increased the soil microbial biomass C (20.7%) and N (26.1%) pools, and these overwhelming effects on microbial biomass were not moderated by crop type or management practices. Crop rotations, especially those that include cover crops, sustain soil quality and productivity by enhancing soil C, N, and microbial biomass, making them a cornerstone for sustainable agroecosystems.

Xiancan Zhu, Luying Sun, F. Song et al.

European Journal of Soil Science • 2018

Sustainable agricultural management practices improve soil processes, prevent soil erosion and consequently enhance crop productivity. The integrated agricultural practice (IP) developed in northeast China, by altering row spacing of planting, adopting no‐tillage and returning all crop residues, showed great benefit in sustaining crop yield. However, its effect on the soil microbiome remains largely elusive. This study evaluated the effect of 12‐year integrated agricultural practice on the structure and activity of the soil microbial community at different soil depths in China's Mollisols zone. The experiment consisted of integrated agricultural practice and conventional practice (CP) treatments in a split‐plot arrangement. The soil microbial community was characterized by MiSeq sequencing. The results showed that agricultural practices affected 12 phyla, 24 classes, 32 orders and 75 families in the bacterial community and one phyla, four classes, 12 orders and 18 families in the fungal community. Integrated agricultural practice resulted in greater bacterial richness and diversity, and increased the relative abundances of Actinobacteria, Gemmatimonadetes, Verrucomicrobia and Ascomycota, but reduced Bacteroidetes, Firmicutes and Basidiomycota in the dominant bacterial and fungal phyla. These findings suggested that integrated agricultural practice modified the soil physiochemical properties and consequently altered microbial community structure and diversity, which in turn affected soil microbial biomass and enzyme activities. These changes under integrated agricultural practice could have contributed to the enhanced crop yield, suggesting that IP is a sustainable agricultural practice.

Qian Zhang, Junjun Wu, Fan Yang et al.

Scientific Reports • 2016

The effect of agricultural land use change on soil microbial community composition and biomass remains a widely debated topic. Here, we investigated soil microbial community composition and biomass [e.g., bacteria (B), fungi (F), Arbuscular mycorrhizal fungi (AMF) and Actinomycete (ACT)] using phospholipid fatty acids (PLFAs) analysis, and basal microbial respiration in afforested, cropland and adjacent uncultivated soils in central China. We also investigated soil organic carbon and nitrogen (SOC and SON), labile carbon and nitrogen (LC and LN), recalcitrant carbon and nitrogen (RC and RN), pH, moisture, and temperature. Afforestation averaged higher microbial PLFA biomass compared with cropland and uncultivated soils with higher values in top soils than deep soils. The microbial PLFA biomass was strongly correlated with SON and LC. Higher SOC, SON, LC, LN, moisture and lower pH in afforested soils could be explained approximately 87.3% of total variation of higher total PLFAs. Afforestation also enhanced the F: B ratios compared with cropland. The basal microbial respiration was higher while the basal microbial respiration on a per-unit-PLFA basis was lower in afforested land than adjacent cropland and uncultivated land, suggesting afforestation may increase soil C utilization efficiency and decrease respiration loss in afforested soils.

Amir Khan, Ajay Veer Singh, S. Gautam et al.

Frontiers in Plant Science • 2023

Addressing the pressing issues of increased food demand, declining crop productivity under varying agroclimatic conditions, and the deteriorating soil health resulting from the overuse of agricultural chemicals, requires innovative and effective strategies for the present era. Microbial bioformulation technology is a revolutionary, and eco-friendly alternative to agrochemicals that paves the way for sustainable agriculture. This technology harnesses the power of potential microbial strains and their cell-free filtrate possessing specific properties, such as phosphorus, potassium, and zinc solubilization, nitrogen fixation, siderophore production, and pathogen protection. The application of microbial bioformulations offers several remarkable advantages, including its sustainable nature, plant probiotic properties, and long-term viability, positioning it as a promising technology for the future of agriculture. To maintain the survival and viability of microbial strains, diverse carrier materials are employed to provide essential nourishment and support. Various carrier materials with their unique pros and cons are available, and choosing the most appropriate one is a key consideration, as it substantially extends the shelf life of microbial cells and maintains the overall quality of the bioinoculants. An exemplary modern bioformulation technology involves immobilizing microbial cells and utilizing cell-free filters to preserve the efficacy of bioinoculants, showcasing cutting-edge progress in this field. Moreover, the effective delivery of bioformulations in agricultural fields is another critical aspect to improve their overall efficiency. Proper and suitable application of microbial formulations is essential to boost soil fertility, preserve the soil’s microbial ecology, enhance soil nutrition, and support crop physiological and biochemical processes, leading to increased yields in a sustainable manner while reducing reliance on expensive and toxic agrochemicals. This manuscript centers on exploring microbial bioformulations and their carrier materials, providing insights into the selection criteria, the development process of bioformulations, precautions, and best practices for various agricultural lands. The potential of bioformulations in promoting plant growth and defense against pathogens and diseases, while addressing biosafety concerns, is also a focal point of this study.

M. Glodowska, M. Woźniak

Agricultural Sciences • 2019

For a constantly growing human population, healthy and productive soil is critical for sustainable delivery of agricultural products. The soil microorganisms play a crucial role in soil structure and functioning. They are responsible for soil formation, ecosystem biogeochemistry, cycling of nutrients and degradation of plant residues and xenobiotics. Certain agricultural treatments, such as fertilizers and pesticides applications, crop rotation, or soil amendment addition, influence the composition, abundance and function of bacteria and fungi in the soil ecosystems. Some of these practices have rather negative effects; others can help soil microorganisms by creating a friendlier habitat or providing nutrients. The changes in microbial community structure cannot be fully captured with traditional methods that are limited only to culturable organisms, which represent less than 1% of the whole population. The use of new molecular techniques such as metagenomics offers the possibility to better understand how agriculture affects soil microbiota. Therefore, the main goal of this review is to discuss how common farming practices influence microbial activity in the soil, with a special focus on pesticides, fertilizers, heavy metals and crop rotation. Furthermore, potential practices to mitigate the negative effects of some treatments are suggested and treatments that can beneficially influence soil microbiota are pointed out. Finally, application of metagenomics technique in agriculture and perspectives of developing efficient molecular tools in order to assess soil condition in the context of microbial activities are underlined.

Maëlle Deshoux, S. Sadet-Bourgeteau, Solène Gentil et al.

SSRN Electronic Journal • 2023

Changes in soil microbial communities may impact soil fertility and stability because microbial communities are key to soil functioning by supporting soil ecological quality and agricultural production. The effects of soil amendment with biochar on soil microbial communities are widely documented but studies highlighted a high degree of variability in their responses following biochar application. The multiple conditions under which they were conducted (experimental designs, application rates, soil types, biochar properties) make it difficult to identify general trends. This supports the need to better determine the conditions of biochar production and application that promote soil microbial communities. In this context, we performed the first ever meta-analysis of the biochar effects on soil microbial biomass and diversity (prokaryotes and fungi) based on high-throughput sequencing data. The majority of the 181 selected publications were conducted in China and evaluated the short-term impact (<3 months) of biochar. We demonstrated that a large panel of variables corresponding to biochar properties, soil characteristics, farming practices or experimental conditions, can affect the effects of biochar on soil microbial characteristics. Using a variance partitioning approach, we showed that responses of soil microbial biomass and prokaryotic diversity were highly dependent on biochar properties. They were influenced by pyrolysis temperature, biochar pH, application rate and feedstock type, as wood-derived biochars have particular physico-chemical properties (high C:N ratio, low nutrient content, large pores size) compared to non-wood-derived biochars. Fungal community data was more heterogenous and scarcer than prokaryote data (30 publications). Fungal diversity indices were rather dependent on soil properties: they were higher in medium-textured soils, with low pH but high soil organic carbon. Altogether, this meta-analysis illustrates the need for long-term field studies in European agricultural context for documenting responses of soil microbial communities to biochar application under diverse conditions combining biochar types, soil properties and conditions of use.

Jing Li, Xueping Wu, M. Gebremikael et al.

PLOS ONE • 2018

Microbial mechanisms associated with soil organic carbon (SOC) decomposition are poorly understood. We aim to determine the effects of inorganic and organic fertilizers on soil labile carbon (C) pools, microbial community structure and C mineralization rate under an intensive wheat-maize double cropping system in Northern China. Soil samples in 0–10 cm layer were collected from a nine-year field trial involved four treatments: no fertilizer, CK; nitrogen (N) and phosphorus (P) fertilizers, NP; maize straw combined with NP fertilizers, NPS; and manure plus straw and NP fertilizers, NPSM. Soil samples were analyzed to determine labile C pools (including dissolved organic C, DOC; light free organic C, LFOC; and microbial biomass C, MBC), microbial community composition (using phospholipid fatty acid (PLFA) profiles) and SOC mineralization rate (from a 124-day incubation experiment). This study demonstrated that the application of chemical fertilizers (NP) alone did not alter labile C fractions, soil microbial communities and SOC mineralization rate from those observed in the CK treatment. Whereas the use of straw in conjunction with chemical fertilizers (NPS) became an additional labile substrate supply that decreased C limitation, stimulated growth of all PLFA-related microbial communities, and resulted in 53% higher cumulative mineralization of C compared to that of CK. The SOC and its labile fractions explained 78.7% of the variance of microbial community structure. Further addition of manure on the top of straw in the NPSM treatment did not significantly increase microbial community abundances, but it did alter microbial community structure by increasing G+/G- ratio compared to that of NPS. The cumulative mineralization of C was 85% higher under NPSM fertilization compared to that of CK. Particularly, the NPSM treatment increased the mineralization rate of the resistant pool. This has to be carefully taken into account when setting realistic and effective goals for long-term soil C stabilization.

Fenghua Wang, Shuaimin Chen, Yuying Wang et al.

Frontiers in Microbiology • 2018

The continuous use of nitrogen (N) fertilizers to increase soil fertility and crop productivity often results in unexpected environmental effects and N losses through biological processes, such as nitrification and denitrification. In this study, multidisciplinary approaches were employed to assess the effects of N fertilization in a long-term (~20 years) field experiment in which a fertilizer gradient (0, 200, 400, and 600 kg N ha−1 yr−1) was applied in a winter wheat-summer maize rotation cropping system in the North China Plain, one of the most intensive agricultural regions in China. The potential nitrification/denitrification rates, bacterial community structure, and abundances of functional microbial communities involved in key processes of the N cycle were assessed during both the summer maize (SM) and winter wheat (WW) seasons. Long-term N fertilization resulted in a decrease in soil pH and an increase in soil organic matter (OM), total N and total carbon concentrations. Potential nitrification/denitrification and the abundances of corresponding functional N cycling genes were positively correlated with the fertilization intensity. High-throughput sequencing of the 16S rRNA gene revealed that the increased fertilization intensity caused a significant decrease of bacterial diversity in SM season, while changed the microbial community composition such as increasing the Bacteroidetes abundance and decreasing Acidobacteria abundance in both SM and WW seasons. The alteration of soil properties markedly correlated with the variation in microbial structure, as soil pH and OM were the most predominant factors affecting the microbial structure in the SM and WW seasons, respectively. Furthermore, consistently with the results of functional gene quantification, functional prediction of microbial communities based on 16S rRNA sequence data also revealed that the abundances of the key nitrificaiton/denitrification groups were elevated by long-term N inputs. Taken together, our results suggested that soil microbial community shifted consistently in both SM and WW seasons toward a higher proportion of N-cycle microbes and exhibited higher N turnover activities in response to long-term elevated N fertilizer. These findings provided new insights into the molecular mechanisms responsible for N loss in intensively N fertilized agricultural ecosystems.

Marie Simonin, Amélie A. M. Cantarel, A. Crouzet et al.

Frontiers in Microbiology • 2018

Metal-oxide nanoparticles (NPs) such as copper oxide (CuO) NPs offer promising perspectives for the development of novel agro-chemical formulations of pesticides and fertilizers. However, their potential impact on agro-ecosystem functioning still remains to be investigated. Here, we assessed the impact of CuO-NPs (0.1, 1, and 100 mg/kg dry soil) on soil microbial activities involved in the carbon and nitrogen cycles in five contrasting agricultural soils in a microcosm experiment over 90 days. Additionally, in a pot experiment, we evaluated the influence of plant presence on the toxicity of CuO-NPs on soil microbial activities. CuO-NPs caused significant reductions of the three microbial activities measured (denitrification, nitrification, and soil respiration) at 100 mg/kg dry soil, but the low concentrations (0.1 and 1 mg/kg) had limited effects. We observed that denitrification was the most sensitive microbial activity to CuO-NPs in most soil types, while soil respiration and nitrification were mainly impacted in coarse soils with low organic matter content. Additionally, large decreases in heterotrophic microbial activities were observed in soils planted with wheat, even at 1 mg/kg for soil substrate-induced respiration, indicating that plant presence did not mitigate or compensate CuO-NP toxicity for microorganisms. These two experiments show that CuO-NPs can have detrimental effects on microbial activities in soils with contrasting physicochemical properties and previously exposed to various agricultural practices. Moreover, we observed that the negative effects of CuO-NPs increased over time, indicating that short-term studies (hours, days) may underestimate the risks posed by these contaminants in soils.

Ana Aguilar-Paredes, Gabriela Valdés, Nicole Araneda et al.

Agronomy • 2023

Conventional agriculture has important challenges to guarantee soil fertility and sustainable food production. Many agricultural soils in the world are degraded and multiple strategies are currently being developed to restore them. The study of beneficial soil microorganisms has attracted increasing interest due to their relevant role in sustainable agricultural development. The balance and maintenance of ecosystem services, such as biomass transformation, nutrient cycling, plant growth, and health, are directly dependent on soil microbial activity. Therefore, it is important to promote its establishment and propagation. An ancient technique that favors soil biodiversity is the production and application of compost. While numerous studies have focused on the benefits of plant cultivation, fewer studies have focused on the benefits for soil microbiota. The objective of this review was to elucidate the role of the microbiota in the composting process and its impact on soil microorganisms in agriculture. The review presents the advances in the knowledge and importance of microorganisms involved in the composting process and how compost promotes the maintenance and multiplication of beneficial microbial consortia and their ecosystem functions in agricultural soils, shifting towards a more sustainable and resilient agriculture.

B. Asadishad, Shawninder Chahal, A. Akbari et al.

Environmental Science &amp; Technology • 2018

Several types of engineered nanoparticles (ENPs) are being considered for direct application to soils to reduce the application and degradation of pesticides, provide micronutrients, control pathogens, and increase crop yields. This study examined the effects of different metal ENPs and their dissolved ions on the microbial community composition and enzyme activity of agricultural soil amended with biosolids. The activity of five extracellular nutrient-cycling enzymes was measured in biosolid-amended soils treated with different concentrations (1, 10, or 100 mg ENP/kg soil) of silver (nAg), zinc oxide (nZnO), copper oxide (nCuO), or titanium dioxide (nTiO2) nanoparticles and their ions over a 30-day period. At 30 days, nZnO and nCuO either had no significant effect on soil enzyme activity or enhanced enzyme activity. In contrast, Ag inhibited selected enzymes when dosed in particulate or dissolved form (at 100 mg/kg). nTiO2 either had no significant effect or slightly decreased enzyme activity. Illumina MiSeq sequencing of microbial communities indicated a shift in soil microbial community composition upon exposure to high doses of metal ions or nAg and negligible shift in the presence of nTiO2. Some taxa responded differently to nAg and Ag+. This work shows how metal ENPs can impact soil enzyme activity and microbial community composition upon introduction into soils amended with biosolids, depending on their type, concentration, and dissolution behavior, hence providing much needed information for the sustainable application of nanotechnology in agriculture.

P. Naughton, R. Marchant, V. Naughton et al.

Journal of Applied Microbiology • 2019

Synthetic surfactants are becoming increasingly unpopular in many applications due to previously disregarded effects on biological systems and this has led to a new focus on replacing such products with biosurfactants that are biodegradable and produced from renewal resources. Microbially derived biosurfactants have been investigated in numerous studies in areas including: increasing feed digestibility in an agricultural context, improving seed protection and fertility, plant pathogen control, antimicrobial activity, antibiofilm activity, wound healing and dermatological care, improved oral cavity care, drug delivery systems and anticancer treatments. The development of the potential of biosurfactants has been hindered somewhat by the myriad of approaches taken in their investigations, the focus on pathogens as source species and the costs associated with large‐scale production. Here, we focus on various microbial sources of biosurfactants and the current trends in terms of agricultural and biomedical applications.

Aditi Pandit, A. Adholeya, D. Cahill et al.

Journal of Applied Microbiology • 2020

Soil environments are dynamic and the plant rhizosphere harbours a phenomenal diversity of micro‐organisms which exchange signals and beneficial nutrients. Bipartite beneficial or symbiotic interactions with host roots, such as mycorrhizae and various bacteria, are relatively well characterized. In addition, a tripartite interaction also exists between plant roots, arbuscular mycorrhizal fungi (AMF) and associated bacteria. Bacterial biofilms exist as a sheet of bacterial cells in association with AMF structures, embedded within a self‐produced exopolysaccharide matrix. Such biofilms may play important functional roles within these tripartite interactions. However, the details about such interactions in the rhizosphere and their relevant functional relationships have not been elucidated. This review explores the current understanding of naturally occurring microbial biofilms, and their interaction with biotic surfaces, especially AMF. The possible roles played by bacterial biofilms and the potential for their application for a more productive and sustainable agriculture is discussed in this review.

Jingjie Hao, Yen Ning Chai, L. D. Lopes et al.

Applied and Environmental Microbiology • 2020

Determining how microbial properties change across different soils and within the soil depth profile will be potentially beneficial to understanding the long-term processes that are involved in the health of agricultural ecosystems. Most literature on soil microbes has been restricted to the easily accessible surface soils. ABSTRACT This study investigated the differences in microbial community abundance, composition, and diversity throughout the depth profiles in soils collected from corn and soybean fields in Iowa (United States) using 16S rRNA amplicon sequencing. The results revealed decreased richness and diversity in microbial communities at increasing soil depth. Soil microbial community composition differed due to crop type only in the top 60 cm and due to location only in the top 90 cm. While the relative abundance of most phyla decreased in deep soils, the relative abundance of the phylum Proteobacteria increased and dominated agricultural soils below the depth of 90 cm. Although soil depth was the most important factor shaping microbial communities, edaphic factors, including soil organic matter, soil bulk density, and the length of time that deep soils were saturated with water, were all significant factors explaining the variation in soil microbial community composition. Soil organic matter showed the highest correlation with the exponential decrease in bacterial abundance with depth. A greater understanding of how soil depth influences the diversity and composition of soil microbial communities is vital for guiding sampling approaches in agricultural soils where plant roots extend beyond the upper soil profile. In the long term, a greater knowledge of the influence of depth on microbial communities should contribute to new strategies that enhance the sustainability of soil, which is a precious resource for food security. IMPORTANCE Determining how microbial properties change across different soils and within the soil depth profile will be potentially beneficial to understanding the long-term processes that are involved in the health of agricultural ecosystems. Most literature on soil microbes has been restricted to the easily accessible surface soils. However, deep soils are important in soil formation, carbon sequestration, and providing nutrients and water for plants. In the most productive agricultural systems in the United States where soybean and corn are grown, crop plant roots extend into the deeper regions of soils (>100 cm), but little is known about the taxonomic diversity or the factors that shape deep-soil microbial communities. The findings reported here highlight the importance of soil depth in shaping microbial communities, provide new information about edaphic factors that influence the deep-soil communities, and reveal more detailed information on taxa that exist in deep agricultural soils.

R. Seenivasagan, O. Babalola

Biology • 2021

Simple Summary Recently in agriculture, the usage of chemical pesticides and fertilizers has increased tremendously. Additionally, it shows severe effects on human health, ecosystem, and groundwater. Environment-friendly methods are used to improve soil fertility, pests, and disease control. Biopesticide and biofertilizers have the future to upgrade sustainable agriculture for many years. This review highlights the efficacy of biofertilizers and biopesticides in improving crop yielding. It provides an eco-friendly and cost-effective method to get more yield for farmers. It describes the prominence of microbial inoculants in plant cultivation. Abstract Farmers are now facing a reduction in agricultural crop yield, due to the infertility of soils and poor farming. The application of chemical fertilizers distresses soil fertility and also human health. Inappropriate use of chemical fertilizer leads to the rapid decline in production levels in most parts of the world, and hence requires the necessary standards of good cultivation practice. Biofertilizers and biopesticides have been used in recent years by farmers worldwide to preserve natural soil conditions. Biofertilizer, a replacement for chemical fertilizer, is cost-effective and prevents environmental contamination to the atmosphere, and is a source of renewable energy. In contrast to chemical fertilizers, biofertilizers are cost-effective and a source of renewable energy that preserves long-term soil fertility. The use of biofertilizers is, therefore, inevitable to increase the earth’s productivity. A low-input scheme is feasible to achieve farm sustainability through the use of biological and organic fertilizers. This study investigates the use of microbial inoculants as biofertilizers to increase crop production.

Marta Bertola, A. Ferrarini, G. Visioli

Microorganisms • 2021

Soil is one of the key elements for supporting life on Earth. It delivers multiple ecosystem services, which are provided by soil processes and functions performed by soil biodiversity. In particular, soil microbiome is one of the fundamental components in the sustainment of plant biomass production and plant health. Both targeted and untargeted management of soil microbial communities appear to be promising in the sustainable improvement of food crop yield, its nutritional quality and safety. –Omics approaches, which allow the assessment of microbial phylogenetic diversity and functional information, have increasingly been used in recent years to study changes in soil microbial diversity caused by agronomic practices and environmental factors. The application of these high-throughput technologies to the study of soil microbial diversity, plant health and the quality of derived raw materials will help strengthen the link between soil well-being, food quality, food safety and human health.

Xinpei Wei, Benkang Xie, Chu Wan et al.

Agronomy • 2024

Soil microorganisms play a crucial role in maintaining the structure and function of soil ecosystems. This study aims to explore the effects of microbial fertilizers on improving soil physicochemical properties and promoting plant growth. The results show that the application of microbial fertilizers significantly increases the richness of soil microorganisms, maintains soil microecological balance, and effectively improves the soil environment. Through various secondary metabolites, proteins, and mucilage secreted by the developing plant root system, microbial fertilizers recruit specific fungal microorganisms. These microorganisms, by binding soil particles with their extracellular polysaccharides and entwining them, fix the soil, enhance the stability of soil aggregates, and ameliorate soil compaction. Moreover, after the application of microbial fertilizers, the enriched soil microbial community not only promotes the plant’s absorption and utilization of key elements such as nitrogen (N), phosphorus (P), and potassium (K), thereby increasing fruit yield and quality, but also competes with pathogens and induces systemic resistance in plants, effectively warding off pathogenic invasions. This study highlights the potential and importance of microbial fertilizers in promoting sustainable agricultural development, offering new strategies and perspectives for future agricultural production.

Mona Parizadeh, Benjamin Mimee, Steven W. Kembel

bioRxiv (Cold Spring Harbor Laboratory) • 2022

ABSTRACT Neonicotinoids, a class of systemic insecticides, have been widely used for decades against various insect pests. Past studies have reported non-target effects of neonicotinoids on some beneficial macro- and micro-organisms. Given the crucial role that the soil microbiota plays in sustaining soil fertility, it is critical to understand how microbial taxonomic composition and gene expression respond to neonicotinoid exposure. To date, few studies have focused on this question, and these studies have evaluated the shifts in soil microbial taxonomic composition or used soil biochemical analyses to assess the changes in microbial functions. In this study, we have applied a metatranscriptomic approach to quantify the variability in soil microbial gene expression in a two-year soybean/corn crop rotation in Quebec, Canada. We identified weak and temporally inconsistent effects of neonicotinoid application on soil microbial gene expression, as well as a strong temporal variation in soil microbial gene expression among months and years. Neonicotinoid seed treatment altered the expression of a small number of microbial genes, including genes associated with heat shock proteins, regulatory functions, metabolic processes and DNA repair. These changes in gene expression varied during the growing season and between years. Overall, the composition of soil microbial expressed genes seems to be more resilient and less affected by neonicotinoid application than soil microbial taxonomic composition. Our study is among the first to document the effects of neonicotinoid seed treatment on microbial gene expression and highlights the strong temporal variability of soil microbial gene expression and its responses to neonicotinoid seed treatments. IMPORTANCE This work provides the first example of the impacts of neonicotinoid seed treatment on community-wide soil microbial gene expression in an experimental design representing real farming conditions. Neonicotinoid pesticides have attracted a great deal of attention in recent years due to their potential non-target impacts on ecological communities and their functions. Our paper represents the first use of metatranscriptomic sequencing to offer real-time and in-depth insights into the non-target effects of this pesticide on soil microbial gene expression and on potentially beneficial soil microorganisms.

E. A. STOCKDALE, P. C. BROOKES

The Journal of Agricultural Science • 2006

Studies of single soil organisms, while useful in specialized cases, e.g. Rhizobia and mycohrrizae, do not yield information on the functioning of the soil ecosystem. This is because most important soil processes, e.g. carbon and nitrogen mineralization, depend upon interactions between entire suites of organisms, many of which still await identification and most of which remain unculturable. For many purposes, treating the soil microbial community as a single, undifferentiated unit, the soil microbial biomass (defined as all soil organisms &lt;5000 μm 3 volume), has much to commend it. It is analogous to studying the forest rather than an individual tree and uniquely permits an understanding of the soil–plant–microbe system as a whole, rather than studying only a small part. The present paper reviews the development of methods to measure microbial dynamics over the last century, the evolution of biomass methodologies and how they have helped the study of crucial soil processes such as nutrient and carbon cycling. Possible future directions for this research are also discussed and an explanation set forth of why the manipulation of this huge population (easily comprising 10 tonnes per hectare of living microbial cells in UK arable soils) has, so far, proved elusive.

Janani Hariharan, Aditi Sengupta, Parwinder Grewal et al.

Agricultural &amp; Environmental Letters • 2017

Core Ideas Microbial function is important but difficult to assess in soil. An omics‐driven tool, PICRUSt, was used to characterize functions of soil microbial communities. No‐tillage compared with plow tillage was functionally enriched for most nutrient cycles. Many other functions integral to soil health can be explored by the PICRUSt omics approach. Soil microbial communities affect the soil's biological, chemical, and physical properties, but there is still a knowledge gap regarding the long‐term impact of tillage practices on soil microbial dynamics. Additionally, the accurate identification of belowground microbial functions is a topic of active interest. In this study, microbial community profiles and functions in soil from a 50‐plus‐year‐old experiment in Ohio, representing one of the world's longest running comparisons of a plow‐tillage system and a continuous no‐tillage system, were compared. The Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) algorithm was used to predict associated functional traits from 16S rRNA gene sequences. Analysis of the sequences revealed a large number of unidentified operational taxonomic units (67%), which is consistent with expectations of the soil ecosystem. Next, we investigated gene and enzyme predictions for nitrogen, sulfur, and methane metabolism and hydrocarbon degradation in soil. Results indicated that no‐tillage was functionally enriched for most nutrient cycles. This study has allowed us to predict distinct functional profiles as a result of legacy land uses. It serves as an example of improved analysis of the functional differences in soil managed by long‐term tillage versus no‐till.

Ene DU

Agricultural Research &amp; Technology: Open Access Journal • 2020

A pot experiment was conducted in the screen house of the Teaching and Research Farm of Rivers State University (RSU)from March to July, 2018 to determine the effects of Effective Microorganisms Activated Solution (EMAS) and organic materials (poultry manure (PM) and dry grasses (DG)) on microbial population and activities. The six treatments made up of 2 levels of EMAS and 3 levels of organic materials were replicated three times and arranged in a Completely Randomized Design (CRD). The treated soils were incubated for 4 weeks and samples collected for microbial count and carbon dioxide evolution. Microbial activities were monitored weekly for 4 weeks. The results show a significant difference (p&lt;0.05) between soil+ effective microorganisms activated solution (SO+EMAS), soil + poultry manure + effective microorganism activated solution(S+PM+EMAS), soil + dry grasses + effective microorganism activated solution (S+DG+EMAS), soil + poultry manure (S+PM), soil + dry grasses (S+DG) and the control soil only (SO). The population of heterotrophic bacterial were significantly different, S+EMAS had the highest (9.82x109CFU/g) and the control (SO) had the least population (1.38x109CFU/g) before planting, SO had the highest population count (4.63x108 CFU/g) and S+DG had the least population count of bacteria (4.10x107CFU/g) after harvest, also a significant different exist among the treatments on CO2 evolution, S+PM had the highest mean value (0.06mg), S+EMAS had the least value (0.002mg). The results show that soils amended with EMAS improved bacterial count, lowers CO2 evolution, soils amended with PM improved CO2 evolution. Hence recommending that EMAS and organic matter (especially PM) should be used for the improvement of soil microbial population to enhance nutrient availabilities for plants and to create a sustainable agriculture.

, Dan Funck Jensen, Mukesh Dubey et al.

Burleigh Dodds Series in Agricultural Science • 2021

The fungus Clonostachys rosea was recognized as an aggressive parasite on other fungi already in the late 1950s. Research into its potential use in biological control of plant diseases soon followed. Today, there are several commercial products based on C. rosea available for biocontrol applications worldwide. Although its mycoparasitic ability has attracted a lot of interest, C. rosea is now viewed as an ecological generalist whose lifestyle also includes plant endophytism, rhizosphere competence and polyphagous ability. Protocols for producing high amounts of C. rosea spores are available for both solid state and liquid fermentation. Low temperature and low moisture content are key factors that influence the shelf life of C. rosea propagules. Products based on C. rosea can be delivered to flowers using bumble bees, applied by spraying or as seed dressing or by incorporation into the soil. Clonostachys rosea is today an established factor in sustainable plant protection strategies.

SHAON MUKHERJEE, JAMAL SIDDIQUI, JUHI SAXENA

The Indian Journal of Agricultural Sciences • 2024

The increased use of chemical fertilizers, pesticides, soil-based heavy metals to improve productivity in agriculture results into higher pollution level in agroecosystem. It has become a major issue on a global scale that seriously jeopardizes people’s health and welfare as well as affects society and overall economy. In view of this, there is an urgent need to detect pollutants in the agroecosystem so that remediation practices can be implemented in time. The evolution of more responsive, affordable and precise technology is needed to create nano-sensors or nanodevices that can be used to monitor agricultural pollution, and the processes involved in pollution control. Major focused ones are those that can detect pollutants at very low concentration levels, as well as point-to-point sensing, in situ, and uninterrupted monitoring devices that offer synchronized data. These sensors are readily available in the market for the detection of organic pollutants, gases, volatile organic molecules, heavy metal ions, hazardous metal ions, etc. but they consume a lot of power and lack sophisticated technologies for improved selectivity and sensitivity. Their precision, sensitivity, response speed and environmental stability under actual operating conditions can all be improved with the aid of nanotechnology. In this study an attempt was made to describe how microbial biosensors can be used to detect toxic materials in agroecosystems. Additionally, an application of nanomaterials as pesticides and antimicrobial agent has also been discussed.

Gabriele Bellotti, Claudia Cortimiglia, Maria Elena Antinori et al.

Microbial Genomics • 2025

Microbial biostimulants (MBs) offer a sustainable approach to agriculture by helping to reduce reliance on synthetic fertilizers. However, as MBs are intentionally released into the environment, their safety should be rigorously assessed. While taxa with qualified presumption of safety (QPS) benefit from established safety indications, non-QPS taxa lack such guidance. To address this gap, we propose a pipeline combining whole genome sequencing (WGS) and extensive literature search (ELS) data to evaluate microbial safety. We analysed public genomes of three QPS species ( Rhodopseudomonas palustris , Bacillus velezensis , Priestia megaterium ) and four non-QPS genera ( Arthrobacter , Azotobacter , Azospirillum , Herbaspirillum ), screening them for virulence factors (VFs), antimicrobial resistance (AMR) genes and mobile genetic elements (MGEs). Results confirmed the safety of QPS taxa, revealing no VFs and only a few intrinsic and non-clinically relevant AMRs. Among non-QPS taxa, VF hits were more prevalent in Azotobacter and Azospirillum spp., though they were mostly related to beneficial plant interactions rather than pathogenicity. AMR genes in non-QPS taxa were primarily associated with efflux pumps or were sporadically distributed. Notably, the only genus-wide pattern observed was that most Azospirillum and Herbaspirillum genomes harboured chromosomally encoded β -lactamases sharing similar genetic structures; however, the detected β -lactamase ( bla ) genes were distantly related to clinically relevant bla variants, and the absence of MGEs suggests a low risk of horizontal gene transfer, indicating the overall safety of these genera. In general, this WGS–ELS framework provides a robust tool for assessing the safety of non-QPS MBs, supporting regulatory decision-making and ensuring their safe use in sustainable agriculture while safeguarding public health.

Yicheng Wu, Guanghua He, Shuiliang Chen et al.

Water Environment Research • 2020

Abstract To achieve deep understandings on the effects of structure and surface properties of anode material on the performance of bioelectrochemical systems, the present research investigated the bacterial community structures of biofilms attached to different three‐dimensional anodes including carbon felt and materials derived from pomelo peel, kenaf stem, and cardboard with 454 pyrosequencing analysis based on the bacterial 16S rRNA gene. The results showed that bacterial community structures, especially the relative abundance of exoelectrogens, were significantly related to the types of adopted three‐dimensional anode materials. Proteobacteria was the shared predominant phylum, accounting for 55.4%, 52.1%, 66.7%, and 56.1% for carbon felt, cardboard, pomelo peel, and kenaf stem carbon, respectively. The most abundant OTU was phylogenetically related to the well‐known exoelectrogen of Geobacter , with a relative abundance of 16.3%, 19.0%, 36.3%, and 28.6% in carbon felt, cardboard, pomelo peel, and kenaf stem, respectively. Moreover, another exoelectrogen of Pseudomonas sp. accounted for 4.9% in kenaf stem and 3.9% in carbonboard, respectively. The results implied the macrostructure and properties of different anode materials might result in different niches such as hydrodynamics and substrate transport dynamics, leading to different bacterial structure, especially different relative abundance of exoelectrogens, which consequently affected the performance of bioelectrochemical systems. Practitioner points Bioelectrochemical systems (BESs) represent a novel biotechnology platform to simultaneously treat wastewaters and produce electrical power. Three‐dimensional materials derived from nature plant as anode to promote electricity output from BESs and reduce the construct cost of BESs. Macrostructure of the three‐dimensional anode material affected phylotype richness and phylogenetic diversity of microorganisms in anodic biofilm of BESs. Geobacter as well‐known exoelectrogen was the most abundant in biofilm attached to three‐dimensional anode.

Kyungmin Kim, Suyeon Lee, Y. Choi et al.

International Journal of Environmental Research and Public Health • 2022

Currently, little is known about the occurrences of fungi-derived microbial volatile organic compounds (mVOCs) in various indoor materials and their detection in residential environments, despite mVOCs being linked to several acute health effects. We identified various mVOCs emitted from fungi grown on PVC wallpaper, silicone rubber, and malt extract agar. We also investigated mVOCs temporal emission and whether fungi-derived VOCs concentration can be used to estimate fungal concentration in the air using active and passive air sampling methods. Among the three fungal growth media included in this study, silicone rubber produced the most variety of mVOCs: 106 compounds (from Aspergillus niger), 35 compounds (from Alternaria alternata), and 85 compounds (from Penicillium chrysogenum). We also found the emission patterns of eight chemical classes (i.e., aromatics, ethers, aliphatics, alcohols, ketones, aldehydes, chlorides, and nitrides) from the three different fungi. From the results of our field experiments in 11 residential environments, passive air samplers led to higher correlations coefficients (0.08 to 0.86) between mVOCs’ air concentrations and airborne fungal concentrations, compared with active air samplers, which showed negative correlation coefficients (−0.99 to −0.02) for most compounds. This study elucidated the occurrence and temporal emission patterns of fungal VOCs in residential environments.

M. Szczotko, Izabela Orych, Łukasz Mąka et al.

Atmosphere • 2022

Aims: With the ongoing pandemic and increased interest in measures to improve indoor air quality, various indoor air purifiers have become very popular and are widely used. This review presents the advantages and disadvantages of various types of technologies used in air purifiers in terms of reducing microbial contamination. Methods: A literature search was performed using Web of Science, Scopus, and PubMed, as well as technical organizations dealing with indoor air-quality to identify research articles and documents within our defined scope of interest. Relevant sections: The available literature data focus mainly on the efficiency of devices based on tests conducted in laboratory conditions with test chambers, which does not reflect the real dimensions and conditions observed in residential areas. According to a wide range of articles on the topic, the actual effectiveness of air purifiers is significantly lower in real conditions than the values declared by the manufacturers in their marketing materials as well as technical specifications. Conclusions: According to current findings, using indoor air purifiers should not be the only measure to improve indoor air-quality; however, these can play a supporting role if their application is preceded by an appropriate technical and environmental analysis considering the real conditions of its use.

Michelle M. McKnight, J. Neufeld

Applied and Environmental Microbiology • 2024

ABSTRACT Nitrification by aquarium biofilters transforms ammonia waste (NH3/NH4+) to less toxic nitrate (NO3-) via nitrite (NO2-). Prior to the discovery of complete ammonia-oxidizing (“comammox” or CMX) Nitrospira, previous research revealed that ammonia-oxidizing archaea (AOA) dominated over ammonia-oxidizing bacteria (AOB) in freshwater aquarium biofilters. Here, we profiled aquarium biofilter microbial communities and quantified the abundance of all three known ammonia oxidizers using 16S rRNA gene sequencing and quantitative PCR (qPCR), respectively. Biofilter and water samples were each collected from representative residential and commercial freshwater and saltwater aquaria. Distinct biofilter microbial communities were associated with freshwater and saltwater biofilters. Comammox Nitrospira amoA genes were detected in all 38 freshwater biofilter samples (average CMX amoA genes: 2.2 × 103 ± 1.5 × 103 copies/ng) and dominant in 30, whereas AOA were present in 35 freshwater biofilter samples (average AOA amoA genes: 1.1 × 103 ± 2.7 × 103 copies/ng) and only dominant in 7 of them. The AOB were at relatively low abundance within biofilters (average of 3.2 × 101 ± 1.1 × 102 copies of AOB amoA genes/ng of DNA), except for the aquarium with the highest ammonia concentration. For saltwater biofilters, AOA or AOB were differentially abundant, with no comammox Nitrospira detected. Additional sequencing of Nitrospira amoA genes revealed differential distributions, suggesting niche adaptation based on water chemistry (e.g., ammonia, carbonate hardness, and alkalinity). Network analysis of freshwater microbial communities demonstrated positive correlations between nitrifiers and heterotrophs, suggesting metabolic and ecological interactions within biofilters. These results demonstrate that comammox Nitrospira plays a previously overlooked, but important role in home aquarium biofilter nitrification. IMPORTANCE Nitrification is a crucial process that converts toxic ammonia waste into less harmful nitrate that occurs in aquarium biofilters. Prior research found that ammonia-oxidizing archaea (AOA) were dominant over ammonia-oxidizing bacteria (AOB) in freshwater aquarium biofilters. Our study profiled microbial communities of aquarium biofilters and quantified the abundance of all currently known groups of aerobic ammonia oxidizers. The findings reveal that complete ammonia-oxidizing (comammox) Nitrospira were present in all freshwater aquarium biofilter samples in high abundance, challenging our previous understanding of aquarium nitrification. We also highlight niche adaptation of ammonia oxidizers based on salinity. The network analysis of freshwater biofilter microbial communities revealed significant positive correlations among nitrifiers and other community members, suggesting intricate interactions within biofilter communities. Overall, this study expands our understanding of nitrification in aquarium biofilters, emphasizes the role of comammox Nitrospira, and highlights the value of aquaria as microcosms for studying nitrifier ecology. Nitrification is a crucial process that converts toxic ammonia waste into less harmful nitrate that occurs in aquarium biofilters. Prior research found that ammonia-oxidizing archaea (AOA) were dominant over ammonia-oxidizing bacteria (AOB) in freshwater aquarium biofilters. Our study profiled microbial communities of aquarium biofilters and quantified the abundance of all currently known groups of aerobic ammonia oxidizers. The findings reveal that complete ammonia-oxidizing (comammox) Nitrospira were present in all freshwater aquarium biofilter samples in high abundance, challenging our previous understanding of aquarium nitrification. We also highlight niche adaptation of ammonia oxidizers based on salinity. The network analysis of freshwater biofilter microbial communities revealed significant positive correlations among nitrifiers and other community members, suggesting intricate interactions within biofilter communities. Overall, this study expands our understanding of nitrification in aquarium biofilters, emphasizes the role of comammox Nitrospira, and highlights the value of aquaria as microcosms for studying nitrifier ecology.

James Naphtali, Alexander W. Y. Chan, F. Saleem et al.

Processes • 2022

On-site wastewater treatment systems (OWTS) are primarily monitored using physiochemical factors, including chemical oxygen demand (COD) and residual total suspended solids (TSS), which are indirect measures of the microbial action during the anaerobic digestion process. Changes in anaerobic digester microbial communities can alter the digester performance, but this information cannot be directly obtained from traditional physicochemical indicators. The potential of metagenomic DNA sequencing as a tool for taxonomic and functional profiling of microbial communities was examined in both common conventional and plug flow-type anaerobic digesters (single-pass and recirculating). Compared to conventional digesters, plug flow-type digesters had higher relative levels of sulfate-reducing bacteria (Desulfovibrio spp.) and hydrogenotrophic methanogens (Methanospirillum spp.). In contrast, recirculating anaerobic digesters were enriched with denitrifier bacteria and hydrogenotrophic methanogens, and both were significantly correlated with physicochemical factors such as COD and TSS. Stratification of microbial communities was observed along the digester treatment process according to hydrolytic, acidogenic, acetogenic, and methanogenic subgroups. These results indicate that the high-throughput DNA sequencing may be useful as a monitoring tool to characterize the changes in bacterial communities and the functional profile due to differences in digester design in on-site systems.

James D. Johnston, Ashlin E Cowger, K. S. Weber

Indoor Air • 2022

Abstract Evaporative cooling is an energy efficient form of air conditioning in dry climates that functions by pulling hot, dry outdoor air across a wet evaporative pad. While evaporative coolers can help save energy, they also have the potential to influence human health. Studies have shown residential evaporative coolers may pull outdoor air pollutants into the home or contribute to elevated levels of indoor bioaerosols that may be harmful to health. There is also evidence that evaporative coolers can enable a diverse microbial environment that may confer early‐life immunological protection against the development of allergies and asthma or exacerbate these same hypersensitivities. This review summarizes the current knowledge of bioaerosol and microbiological studies associated with evaporative coolers, focusing on harmful and potentially helpful outcomes from their use. We evaluate the effects of evaporative coolers on indoor bacterial endotoxins, fungal β‐(1 → 3)‐D‐glucans, dust mite antigens, residential microbial communities, and Legionella pneumophila. To our knowledge, this is the first review to summarize and evaluate studies on the influence that evaporative coolers have on the bioaerosol and microbiological profile of homes. This brings to light a gap in the literature on evaporative coolers, which is the lack of data on health effects associated with their use.

J. Weidhaas, M. Olsen, J. McLean et al.

Journal of Water Reuse and Desalination • 2022

Arid and semi-arid locations are increasingly utilizing nontraditional irrigation water including reclaimed wastewater. Human health risk associated with reclaimed wastewater use was determined by testing reservoir, distribution line and home spigot water (n=190) and 14 types of vegetables and fruits (n=90) harvested from 5 home gardens for 7 waterborne pathogens, 47 antibiotic resistance genes and 12 pharmaceuticals and personal care products (PPCPs). Based on surveys of the residents’ use of the reclaimed wastewater, two exposure routes were modeled: irrigation of fruits and vegetables and drinking from irrigation hoses. Probabilistic quantitative microbial risk assessment indicated that consumption of raw vegetables and fruits exceeded a 0.015 benchmark illness rate due to adenovirus and enterococci. Chemical risk assessments indicated that consumption of tons of vegetables per day and hundreds to millions of gallons of water per day would be needed to reach an unacceptable risk among the 10 PPCPs detected in home spigot water, indicating de minimis risk from PPCPs. Eight different drug resistance gene families were detected in the water samples and crops indicating that antibiotic-resistant organisms are present on foods irrigated with reclaimed water containing pharmaceuticals. These results elucidate the combined risk from pathogens and PPCPs from reclaimed wastewater irrigation.

R. Arbianti, T. S. Utami, Vifki Leondo et al.

IOP Conference Series: Materials Science and Engineering • 2018

Microbial Fuel Cell (MFC) provides a new alternative in the treatment of organic waste. MFC produces 50-90% less sludge to be disposed than other methods. MFC technology can utilize existing microorganisms in the waste as a catalyst to generate electricity and simultaneously also serves as a wastewater treatment unit itself. Tempeh wastewater is one of the abundant industrial wastewater which can be processed using MFC. Research using the selective mixed culture is very likely to do due to the good result on COD removals by adding mixed culture. Microorganisms in tempeh wastewater consist of bacteria gram positive and gram negative. This study focused on the aspects of waste treatment which is determined by decreased levels of COD and BOD. Variations in this study are the formation time of biofilm and the addition of selective gram. MFC operated for 50 hours. For a variation of biofilm formation, experiments were performed after incubation by replacing incubation substrates used in the formation of biofilms. Biofilm formation time in this study was 3 days, 5 days, 7 days and 14 days. Gram positive and gram negative bacteria were used in selective mixed culture experiments. Selective mixed culture added to the reactor by 1 mL and 5 mL. Selection of gram-positive or gram-negative bacteria carried by growing mixed culture on selective media. COD and BOD levels were measured in the wastewater before and after the experiment conducted in each variation. Biofilm formation optimum time is 7 days which decrease COD and BOD levels by 18.2% and 35.9%. The addition of gram negative bacteria decreases COD and BOD levels by 29.32% and 51.32%. Further research is needed in order to get a better result on decreasing levels of COD and BOD.

D. Pant, G. V. Bogaert, Y. Alvarez-Gallego et al.

Environmental Engineering and Management Journal • 2016

Microbial Fuel Cells (MFCs), the bioelectrochemical devices for conversion of waste into electricity through bacterial metabolic activity can use substrates with different complexity and strength. Wastewaters with moderate to high organic content can be exploited as MFC substrates. In this study, four different industrial wastewaters (from a chemical company, milk industry, soyabased food and soft-drink company and laundry) with different compositions were used as substrates in identical MFCs. In the design of MFC, carbon cloth was used as anode and low-cost carbon based, non-platinized electrode as air cathode. Anode and cathode were separated by an ion permeable membrane Zirfon , directly attached on the cathode. After initial operation with 10 mM acetate as substrate, the cells were switched to real industrial wastewaters without pre-treatment. When operational, an electrochemically active biofilm and anode open circuit voltage (OCV) of -500 mV vs. Ag/AgCl. OCV was obtained which recovered after dropping in all cells, showing the ability of anodic bacteria to utilize industrial wastewaters as substrate. A maximum power of 419 mW m-2 was obtained with milk industry wastewater, while the electrodes in MFC with chemical industry wastewater were corroded after few days of operation suggesting that every wastewater is not suitable as substrate for electricity production and treatment in MFCs.

Natchapon Srinak, Porntip Chiewchankaset, S. Kalapanulak et al.

PLOS Computational Biology • 2024

The efficiency of microbial fuel cells (MFCs) in industrial wastewater treatment is profoundly influenced by the microbial community, which can be disrupted by variable industrial operations. Although microbial guilds linked to MFC performance under specific conditions have been identified, comprehensive knowledge of the convergent community structure and pathways of adaptation is lacking. Here, we developed a microbe-microbe interaction genome-scale metabolic model (mmGEM) based on metabolic cross-feeding to study the adaptation of microbial communities in MFCs treating sulfide-containing wastewater from a canned-pineapple factory. The metabolic model encompassed three major microbial guilds: sulfate-reducing bacteria (SRB), methanogens (MET), and sulfide-oxidizing bacteria (SOB). Our findings revealed a shift from an SOB-dominant to MET-dominant community as organic loading rates (OLRs) increased, along with a decline in MFC performance. The mmGEM accurately predicted microbial relative abundance at low OLRs (L-OLRs) and adaptation to high OLRs (H-OLRs). The simulations revealed constraints on SOB growth under H-OLRs due to reduced sulfate-sulfide (S) cycling and acetate cross-feeding with SRB. More cross-fed metabolites from SRB were diverted to MET, facilitating their competitive dominance. Assessing cross-feeding dynamics under varying OLRs enabled the execution of practical scenario-based simulations to explore the potential impact of elevated acidity levels on SOB growth and MFC performance. This work highlights the role of metabolic cross-feeding in shaping microbial community structure in response to high OLRs. The insights gained will inform the development of effective strategies for implementing MFC technology in real-world industrial environments.

Shuai Zhao, Pu Liu, Yongyan Niu et al.

Sensors • 2018

Hexavalent chromium (Cr(VI)) is a well-known toxic heavy metal in industrial wastewater, but in situ and real time monitoring cannot be achieved by current methods used during industrial wastewater treatment processes. In this study, a Sediment Microbial Fuel Cell (SMFC) was used as a biosensor for in situ real-time monitoring of Cr(VI), which was the organic substrate is oxidized in the anode and Cr(VI) is reduced at the cathode simultaneously. The pH 6.4 and temperature 25 °C were optimal conditions for the operation. Under the optimal conditions, linearity (R2 = 0.9935) of the generated voltage was observed in the Cr(VI) concentration range from 0.2 to 0.7 mg/L. The system showed high specificity for Cr(VI), as other co-existing ions such as Cu2+, Zn2+, and Pb2+ did not interfere with Cr(VI) detection. In addition, when the sediment MFC-based biosensor was applied for measuring Cr(VI) in actual wastewater samples, a low deviation (<8%) was obtained, which indicated its potential as a reliable biosensor device. MiSeq sequencing results showed that electrochemically active bacteria (Geobacter and Pseudomonas) were enriched at least two-fold on the biofilm of the anode in the biosensor as compared to the SMFC without Cr(VI). Cyclic voltammetry curves indicated that a pair of oxidation/reduction peaks appeared at −111 mV and 581 mV, respectively. These results demonstrated that the proposed sediment microbial fuel cell-based biosensor can be applied as an early warning device for real time in situ detection of Cr(VI) in industrial wastewaters.

I. W. Suryawan, I. Septiariva, Ariyanti Sarwono

Indonesian Journal of Environmental Management and Sustainability • 2020

The purpose of this review is to provide current information regarding industrial wastewater treatment with MFC technology with the addition of biocatalysts and pretreatments. Moreover, this review also updates industrial waste treatment technology with MFC technology in Indonesia. Waste could be generated from domestic activities as well as non-domestic activities, such as industries. Industries produce waste with quite high organic content. This organic material is not easily degraded in biological treatment. Wastewater treatment, currently, aims only to meet standards quality and not to reuse. In Indonesia, the reuse processes, one of which is still rarely found in the form of energy. Industries that can process and convert wastewater energy can help the government realize sustainable development in the energy sector. One of the technologies is the Microbial Fuel Cell (MFC). Previous MFC research that had been carried out was limited to laboratory scale with a volume of less than 1 L and, among them, used mixed or artificial waste. MFC processing uses anode in wastewater as a substrate source and generates electrons under anaerobic conditions. Electron formation could be accelerated by adding biocatalysts such as enzymes and specific microorganisms. The processing occurred in an anaerobic anode that could be increased by increasing the substrate's biodegradability value in the waste. The biodegradability value can be increased by pretreatment with ozone or ultrasonic technology. In Indonesia, research on industrial wastewater treatment with MFC as well as biocatalyst and pretreatment is still relatively minimal.

A. Pugazhendi, Afnan Eid Al‐Mutairi, M. Jamal et al.

International Journal of Energy Research • 2020

The present study investigated seafood industrial wastewater treatment with corresponding power generation in air cathode microbial fuel cell under saline condition (40 g/L). The results recorded total chemical oxygen demand) removal of 52 ± 1.8%, 64 ± 1.1%, 85 ± 1.2%, 89 ± 1.4%, and 76 ± 1.2% to the corresponding organic load (OL) of 0.5, 0.75, 1, 1.25, and 1.5 gCOD/L under saline condition. Soluble chemical oxygen demand reduction was in the range of 46% to 78% at OL of 0.5 to 1.5 gCOD/L. The maximum power density (530 ± 15 mW/m2) and coulombic efficiency (52 ± 2.4%) was procured at the OL of 1.25 and 0.5 gCOD/L, respectively. Total suspended solids removal was 74 ± 1.5% at OL of 1.25 gCOD/L and 64 ± 1.3% at OL 1.5 gCOD/L. Bacterial community analysis for anode region samples for OL 0.5 and 1 gCOD/L was extensively dominated by Bacillus (MN880233) with 75.8% and 55.8%, respectively. Interestingly at 1.25 gCOD/L OL, Rhodococcus (MN880237) was predominant (42.3%) strain in the anode region and recorded high power production under saline condition. Sludge samples subjected to phylogenetic analysis explored the dominance of Clostridium, Turicibacter, and Marinobacter at different OL from 0.5 to 1.5 gCOD/L. Bacterial community results at 1.25 gCOD/L of OL sludge samples revealed completely different strains of dominancy in the community. Marinobacter (53.3%), Ochrobactrum (19.3%), and Bacillus (8.1%). Thus, the phylogenetic analysis of the anodic and sludge samples clearly detailed the presence of halophilic bacterial strains with high potential to treat seafood processing industrial wastewater and excellent exoelectrogenic activity for power production.