Olivia McKay, Grace Pold, Philip Martin et al.

Frontiers in Environmental Science • 2022

Agricultural plastics support crop production and quality by reducing weeds, improving irrigation efficiency, and regulating soil conditions, but can also become a soil pollutant. While microplastic effects on soil function are increasingly well-understood, the impacts of agricultural macroplastic (>5 mm) contamination on soils are poorly documented. Prolonged exposure to plastic macrofragments may alter microbial decomposer community structure and function, since plastic can directly affect edaphic factors while leaching novel compounds. To better characterize how plastic contamination influences the soil habitat, we sampled three farms characterized by agricultural plastic pollution in Monterey County, CA, United States. Using a randomized block design, we collected surface soil samples from the fields (“bulk PC soil”) to compare with soil directly in contact with the remaining polyethylene (PE) mulch and polyvinyl chloride (PVC) dripline fragments (“plastic-associated soil”). Soil directly associated with plastic fragments was hypothesized to have reduced microbial biomass and decomposer activities relative to the bulk soil, due to a greater likelihood of toxicity. In contrast to our expectations, we found that both PE and PVC macrofragments support a distinct microbial habitat that hosts a larger, more efficient microbial biomass with greater labile nutrient pools than the surrounding bulk soil. Because of the scope of macroplastic pollution likely occurring in agricultural soils, our findings suggest that this novel plastisphere habitat may significantly alter ecological functions critical to agricultural soils over time by encouraging microbial colonization within plastic debris.

, Jeya Bharathi M, Balachandar D et al.

Madras Agricultural Journal • 2011

Precision farming is an integrated plant nutrient management system attempt to deliver the inputs actual crop needs without disturbing the entire farming area. The fertilizers in liquid state will be delivered through laterals directly to the root zone at high concentrations. Soil microorganisms are potential resources for soil productivity and sustainability, intended to be influenced by various anthropogenic-and farming activities. Hence in present study, we have investigated that the effect of different dose of liquid fertilizers on changes in soil microbial populations and enzyme activities of maize in comparison with conventional practice of fertilization. The results clearly revealed that all the fertilization reduced the microbial population and enzyme activities of maize rhizosphere and among the fertigations, 75 per cent of recommended NPK in the form of liquid fertilizer had a less reduction in the population of Azospirillum, P solubilising bacteria and total diazotrophs, soil respiration and enzyme activities. Hence it is evident from the study that the use of more organic manures and microbial inoculants along with inorganic chemicals fertilizers, as integrated approach is needed for precision farming.

, Thiruveni T, Shanthi M et al.

Madras Agricultural Journal • 2012

A field experiment was conducted during Kharif 2009 to evaluate the microbial consortia mediated resistance against okra shoot and fruit borer, Earias vittella (Fab.) in okra variety, Arka Anamika and hybrid, CoBhH1. The microbial consortium Pseudomonas fluorescens Pf1 + Beauveria bassiana B2 isolate (Pf1 + B2) was effective in reducing the shoot and fruit borer infestation through seed treatment, soil application and foliar spray. Pf1 + B2 recorded minimum shoot damage during vegetative and reproductive phases (3.99 and 14.33 %) as against untreated check (13.58 and 24.16 %). Fruit infestation was less in Pf1 +B2 consortia treatments on weight and number basis (4.22 and 2.83%), whereas it was 13.59 and 17.96 per cent in untreated check. Phenol content was high in Pf1+B2 consortia treated plants in Arka Anamika (0.94 mg/g) and CoBhH1 (1.39 mg/g), as against untreated check (0.20 and 0.41 mg/g, respectively). There was significant negative correlation between the shoot and fruit borer infestation and phenols (r=-0.937**), defensive enzymes viz., peroxidase (r=-0.909*), poly phenol oxidase (r=-0.993**), and phenyl alanine ammonia lyase (r=-0.960**).

Youming Shen, Jiyun Nie, Lixue Kuang et al.

Microbial Biotechnology • 2021

Summary The development of DNA sequencing technology has provided an effective method for studying foodborne and phytopathogenic microorganisms on fruits and vegetables (F & V). DNA sequencing has successfully proceeded through three generations, including the tens of operating platforms. These advances have significantly promoted microbial whole‐genome sequencing (WGS) and DNA polymorphism research. Based on genomic and regional polymorphisms, genetic markers have been widely obtained. These molecular markers are used as targets for PCR or chip analyses to detect microbes at the genetic level. Furthermore, metagenomic analyses conducted by sequencing the hypervariable regions of ribosomal DNA (rDNA) have revealed comprehensive microbial communities in various studies on F & V. This review highlights the basic principles of three generations of DNA sequencing, and summarizes the WGS studies of and available DNA markers for major bacterial foodborne pathogens and phytopathogenic fungi found on F & V. In addition, rDNA sequencing‐based bacterial and fungal metagenomics are summarized under three topics. These findings deepen the understanding of DNA sequencing and its application in studies of foodborne and phytopathogenic microbes and shed light on strategies for the monitoring of F & V microbes and quality control.

, Selvi D, et al.

Madras Agricultural Journal • 2022

The studyaimed to evaluate the efficiencyof different sources of Zinc and organic manures with and without microbial inoculants on the bioavailability of Zinc in soil. Four different zinc sources namely ZnSO4, ZnPO4, ZnO, and Zn-EDTA, and two organic manures viz., farm yard manure (FYM) and Vermicompost (VC) were evaluated in the presence and absence of Zinc Solubilizing Bacteria (ZSB). Among the different combinations of the above factors, ZnSO4+FYM+ZSB combination recorded a maximum reduction in pH (6.82) whereas, ZnSO4+Vermicompost+ZSB recorded the highest Electrical Conductivity (EC) (0.4 dSm-1). Regarding DTPA-Zn availability Zn-EDTA recorded the highest concentration in soil both as a sole and combined application with organic and microbes. The dehydrogenase activity was upsurged in organic applied treatments and was less in fertilizer applied treatments. Zinc oxide recorded maximum dissolution efficiency compared to other sources of Zinc.

Rosa Boone, Bjorn Robroek, Wim van der Putten et al.

• 2025

Our current agricultural system is non-sustainable due to its negative impact on soil and water quality, and its eroding effect on biodiversity. To promote sustainability while maintaining productivity, we need to explore alternative practices. One such strategy is the extensification of agricultural management, which reduces external inputs while aiming to enhance soil functioning. Nutrient cycling, a key soil function, may improve under extensification due to shifts in abiotic conditions and microbial community interactions. However, the mechanisms by which extensification affects soil microbial communities and their functional interactions in field conditions remain poorly understood. In this study, we investigated how management extensification affects soil nutrient cycling. We assessed nutrient cycling using enzymatic assays, Microresp analysis, and Teabag decomposition, and evaluated the role of abiotic factors (e.g., pH, SOC) and microbial community composition along an agricultural extensification gradient, ranging from conventional productive grasslands to semi-natural grasslands. Microbial interactions were explored using co-occurrence network analysis to assess how management influences the community as a whole. Preliminary results show that fungal communities change with extensification, accompanied by an increase in overall soil nutrient functioning, particularly for decomposition rate. Our results highlight that management choices have implications for soil functioning, and that the validity to use soil parameters to underpin soil nutrient functioning are highly context dependent.

Armi Kaila

Agricultural and Food Science • 1951

An attempt has been made in the present investigation to elucidate the influence of growing legumes upon the microbial population and upon its activities in the soil. Annual legumes, pea and vetch were compared with oats, and red clover with timothy. At the beginning and at the end of the summer the number of bacteria, calculated through various culture media, appeared to be greater in the rhizosphere of the pea plants than under the vetch or oat plants. The rhizosphere flora of the young pea plants showed a capacity for more active nitrogen fixation than that of the young vetch or oat plants, but later the superiority of the pea plants disappeared. A higher rate of nitrification under and for some time after the legume crops compared with the corresponding non-legume crops was noted. Nitrification of added ammonium sulfate did not occur more actively under the legumes, due either to the lack of a stimulation of the nitrifying flora, or to the higher acidity in the legume soils. Compared with the non-legumes, the legumes could not be found to stimulate carbon dioxide production from the soil in any other way than through their more easily decomposable residues. Within the bounds of this investigation no special effect of legumes upon the soil flora could be established that cannot be explained on the basis of their nitrogen economy, either their utilizing soil nitrogen to a smaller degree than non-legumes, or due to composition of their roots and stubble. Under the field conditions, however, several other factors not demonstrable from this material may exist.

Yadollah. Ghafuri, Ahmad Reza. Yari, Saeed. Shams et al.

Research Square • 2022

Abstract Background This study was designed to investigate microbial exposure risk assessment and consequences of adverse health effects due to the use of irrigation of fields with wastewater in Qom province Methods Environmental monitoring program for 3 pathogens including Escherichia coli, Vibrio cholerae and Ecoli O157 in raw sewage and treated wastewater and irrigated products with wastewater, was performed. Results Results was shown that in the raw wastewater, concentrations of E.coli, Vibrio Cholerae and E.coli O157:H7, 3.4×103±500, 2.1×103±100 and 312 respectively were determined. Concentrations of E.coli, Vibrio Cholerae and E.coli O157:H7 in wastewater effluent 2.1×103±100, 0.8×103±100 and 176 respectively were determined. Based on these findings, it is determined that the conventional wastewater treatment system has been effective in removing E.coli, Vibrio Cholerae and E.coli O157: H7 by 50%, 59% and 43%, respectively. Irrigated crops with wastewater effluent containing 400±250, 0.1×103±0.019 and 52 for E.coli, Vibrio Cholerae and E.coli O157:H7 respectively were measured. In this study according to the exposure scenarios including accidental drinking, food crop consumption, dermal contact by wastewater effluent and dermal contact by raw wastewater, total annual Probability of infection in studied population for E.coli, Vibrio Cholerae and E.coli O157:H7, 8×10-2, 8×10-4 and 0.17 respectively was determined. Conclusions Implementing of wastewater safety plans (WWSP) to safeguard wastewater quality, raising awareness in the population in contact with urban wastewater and upgrading wastewater treatment plants is inevitable.

Hui Li, Shuwen Gu, Libao Wang et al.

Fishes • 2024

The aim of this study was to investigate the dynamic changes in the microbial communities of both the environment and gut of Litopenaeus vannamei, as well as to elucidate the mechanisms underlying microbial community assembly in greenhouse farming. 16S rDNA high-throughput sequencing and bioinformatics methods were used to carry out the research on the community structure of the microorganisms under greenhouse culture conditions in water, sediment, and gut microorganisms; correlations pertaining to environmental factors; the feasibility of using Source Tracker; and the mechanisms of community construction. The results show that the dominant microorganisms in water, sediment, and gut farming in a greenhouse environment varied and were subject to dynamic change. A variety of beneficial microbiota such as Bacillus were found in the gut, whereas a variety of microorganisms such as Marivita and Pseudomonas, which function as nitrogen and phosphorus removers, were present in water. Source Tracker and environmental correlation analyses showed that changes in the gut were associated with eutrophication indicators (total nitrogen, total phosphorus, ammonia nitrogen) and changes in environmental microorganisms (in water and sediment). The results of the community-building mechanism analysis show that stochastic processes determine the community-building directions of environmental and gut microorganisms. These findings will help us to understand the microbiota characteristics of shrimp ponds under greenhouse farming conditions, and the complex interactions between the shrimp gut and the environmental microbiota and environmental variables, as well as revealing the changing rules of the gut microbiota.

Vito Abbruzzese

• 2021

The data presented here are related to the research article entitled ‘Effects ofsubstrate quality on carbon partitioning and microbial community composition in soil from an agricultural grassland’ [1]. Data illustrate cumulative CO2 efflux, microbial biomass C (Cmic), priming effect expressed as priming index (PI) and total phospholipid fatty acid (PLFA) profiles. The data were measured during four soil laboratory incubations using a silty clay loam soil under permanent grassland from May until August 2015. The soil was treated with carbohydrates of different complexity (glucose, glucose-6-phosphate (G6P) or cellulose) alone or in conjunction with livestock slurry amended or non-amended with a biological additive. Our data may be of great significance for further studies on microbial respiration and biosynthesis, and microbial community structure following slurry application to soil, alongside the potential beneficial effects of the addition of slurry amended with biological additives.

Sudhamayee Behura

African Journal of Biological Sciences • 2024

Environmental pollution from agricultural activities poses significant challenges globally. Bioremediation, using microbial diversity to degrade contaminants, offers a sustainable solution. This study explores microbial diversity's potential in agricultural waste bioremediation. Agricultural wastes, including crop residues and agro-industrial by-products, contribute to soil degradation and water pollution

Zahra F. Islam, Chris Greening, Hang‐Wei Hu

Microbial Biotechnology • 2023

Abstract Hydrogen‐oxidising bacteria play a key role in maintaining the composition of gases within the atmosphere and are ubiquitous in agricultural soils. While studies have shown that hydrogen accumulates in soil surrounding legume nodules and the soil surface, soils as a whole act as a net sink for hydrogen, raising questions about how hydrogen is internally recycled by soils. Can the energy derived from hydrogen oxidation be directly funnelled into plants to promote their growth or does it only act as a booster for other plant‐growth promoting bacteria? Moreover, while the fertilisation effect of hydrogen on plants has previously been shown to be beneficial, questions remain about the upper limit of hydrogen uptake by plants before it becomes detrimental. Agricultural practices such as fertilisation may impact the balance of hydrogen‐oxidisers and hydrogen‐producers in these ecosystems, potentially having detrimental effects on not only agricultural land but also global biogeochemical cycles. In this perspectives piece, we highlight the importance of understanding the contribution of hydrogen to agricultural soils and the effects of agricultural practices on the ability for bacteria to cycle hydrogen in agricultural soils. We propose a framework to gain better insights into microbial hydrogen cycling within agroecosystems, which could contribute to the development of new agricultural biotechnologies.

Elena I. Gavrikova, Roman V. Shkrabak, Vladimir S. Shkrabak et al.

Bulletin Samara State Agricultural Academy • 2025

Food production carried out by workers in a number of sub-sectors of the agro-industrial complex is inextricably linked with their identification with the sources of microbial contamination. Largely, this applies to the types of activity carried out in stationary facilities of the industry year-round or seasonally in some types of work. This is evidenced by the information provided in the article on the annual commissioning of new stationary facilities in the country for year-round keeping of animals, poultry, storage and processing of products in order to resolve issues of food supply of the population and raw materials for industry. As a rule, these are objects with permanent sources of microbial contamination. Workers engaged in industries with increased microbial contamination are susceptible to pathological processes caused by the chronicity of the infectious process and a decrease in the body's immune resistance. Microorganisms and their waste products found in the working area of a number of livestock, poultry, plant growing, fruit and vegetable (including greenhouse) industries lead to an increased susceptibility to infections, diseases, and, consequently, to an increase in the periods of temporary disability. Designing technical means and compiling disinfectant compositions to correct the level of microbial contamination leads to a decrease in the overall incidence rate and periods of temporary disability of workers, which will increase labor productivity and reduce the labor intensity of obtaining products. In this regard, an original model system was proposed in which the antioxidant properties of essential oils were studied by reaction with thiobarbituric acid under different experimental conditions (with and without heating). As a result of the experiments, it was found that heated anise essential oil and Morrison mustard plaster essential oil have the greatest anti-free radical activity. Devices for introducing essential oils into the respiratory tract have been developed. A method of phytodisinfection is proposed for air treatment, as a result of which the total microbial contamination in the premises is reduced on average by 3 times, the content of mold fungi - by 4 times.

, Katya Dimitrova

Agricultural Sciences • 2024

The establishment of eco-friendly principles in agriculture requires, from one side, a reduced dependence on chemical fertilizers, pesticides and herbicides, and on the other, a maintenance of consistent yield and high plant productivity. Such substantial shift in the contemporary agricultural practices can be achieved only if a wide variety of alternative options is available. Furthermore, in order to become part of agricultural practices these options have to be affordable in a broad scale and effective against the loss of biodiversity and reduced soil fertility. The current study presents data about the metabolic activity and microbial community` structure in two soil samples – one treated with chemical fertilizer and another treated with chemical fertilizer reduced by 25% dose and supplemented with commercially available biofertilizer. Metabolic activity and properties of microbial soil communities were assessed by the BIOLOG® EcoPlate technique. The estimated parameters included average well-color development (AWCD) and utilisation of six guilds of substrates. Several functional indexes that are used for evaluation of community diversity and evenness were also estimated. The AWCD, expressed either as total activity or as guilds utilisation during the EcoPlate incubation period of seven days did not reveal significant difference between variants. However, most of the estimated functional indexes consistently indicated higher microbial diversity and more balanced structure of microbial community in the biofertilizer-supplemented variant. The results clearly implied that the biofertilizer based on nitrogen-fixing bacteria can positively influence the structure of soil communities and its application could be beneficial for soil fertility and plant productivity. Keywords: diazotroph, biofertilizer, BIOLOG® EcoPlate, functional indexes, metabolic activity, microbial communities

Kalisa Bogati, Piotr Sewerniak, Maciej Walczak

bioRxiv (Cold Spring Harbor Laboratory) • 2024

Abstract In this study, the impact of a two-month of drought stress on the microbial abundance, their enzymes and functional diversity in four agricultural soil (Gniewkowo (G), Lulkowo (L), Nieszawa (N), and Suchatówka (S) sites from Poland) was investigated during summer season. The physicochemical parameters (pH, organic carbon (C), calcium carbonate (CaCO 3 ), total nitrogen (N), nitrate (NO 3 - ), ammonium (NH 4 + ), total phosphorus (P), available phosphate (P 2 O 5 )), and specific biological parameters (microbial abundance, CLPP, and soil enzymes (phosphatases (acid; ACP and alkaline; AKP), dehydrogenase (DH), and urease (UR)) were conducted on the soil samples in this study. The physicochemical and biological data were compared between zero-week (T0) and 8 th week (T8) time intervals. The microbial enumeration showed higher bacterial populations (496.63 x 10 4 CFU g -1 dry soil) compared to actinomycetes (13.43 x 10 4 CFU g −1 dry soil), and lowest were the fungal population (67.68 x 10 2 CFU g -1 dry soil) at T8. The functional diversity showed strong positive significance in the G, N and S sites at T8. On the contrary, most of the L sites showed negative significance with the utilization of amines only, by the end of the experiment. Overall, the microbial population, their enzymes and functional diversity showed positive correlation with soil moisture content in all four investigated sites. The findings of our study indicate that soil biological activities in agricultural regions can be modified by a mere two months of drought.

Giovana P. F. Macan, Manuel Anguita-Maeso, Blanca B. Landa

• 2023

Currently, plastic mulch debris represent one of the main sources of microplastic pollution in agricultural soils. However, there is still limited research on plastic and microorganisms' interaction in terrestrial agroecosystems as compared to marine ecosystems. In this study, we have characterized the microbial communities associated with agricultural plastic mulch debris by using culture-dependent, and culture-independent (i.e., high-throughput DNA sequencing) approaches. Weathered plastic mulch debris samples were collected from the topsoil of five agricultural fields in Baza, Granada province in southern Spain, characterized by intensive horticultural production over the last ten years. The bacterial communities from the plastisphere soil (soil tightly adhered to the plastic) as well as the community tightly attached to the plastic surface were assessed by estimating the culturable populations by dilution plating on general media and the total (culturable and non-culturable) populations by NGS analysis of 16S rRNA amplicons. Additionally, all the plastic samples were characterized by FTIR spectroscopy and identified as polyethylene. The results from the culturable approach showed a significantly higher number of colony-forming units in the plastisphere soil than on the plastic surface, revealing some differences among field plots. Furthermore, 16S rRNA amplicon sequencing showed that the bacterial alpha-diversity, as measured by Richness index was higher in the plastisphere soil. Beta diversity Weighted-UniFrac index indicated that the main significant differences in the bacterial communities occurred among field plots, which might be related to the soil type, and/or crop history, and a lower effect of the plastic niche sampled. Some genera such as Arthrobacter, Bacillus, Blastococcus, Kocuria, Nocardioides, Sphingomonas, and Streptomyces were present in high abundance on both plastisphere soil and plastic surface from all the assessed fields. Furthermore, in one of the fields, the genera Polycyclovorans and Bdellovibrio showed significantly higher abundance in the plastic surface than in the plastisphere soil, indicating in this case a selective effect of the plastic for specific bacterial genera. Further research is still needed to better understand the potential impacts of plastic pollution on terrestrial agroecosystems as well as the complex interaction between plastic and microorganisms.“This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 955334 - SOPLAS.”

, Wagner Bettiol, Flávio Henrique Vasconcelos de Medeiros et al.

Burleigh Dodds Series in Agricultural Science • 2021

The success of a biological control programme depends on the isolation and selection of antagonists. There is an enormous diversity of culturable microbial species in the soil, rhizosphere, phylloplane, spermosphere and carposphere, which can be used in the isolation and selection of antagonists. The structures of fungal plant pathogens concerned with survival and infection may also be sources of antagonists. Although non-culturable microorganisms and microbiome-based strategies have great potential for development as commercial products in disease control, more knowledge is needed to understand the mechanisms involved in interactions between plants and complex microbial communities. Methods of isolation and selection of the most commercially exploited groups of antagonists and their advantages and disadvantages are discussed in this chapter as well as those of non-traditional antagonists. Finally, possible strategies for engineering the soil and host microbiome to actively promote plant protection against pathogens are discussed.

Vito Abbruzzese

• 2021

The long-term application of livestock slurry to intensive grassland soils may lead to positive effects, including an increase in soil organic matter and plant nutrient supply to soils. Further, there is increasing interest in the potential of biological slurry additives (mixtures of selected living or latent microorganisms added to slurry) to enhance soil fertility through mobilisation of key elements in slurry and soil. However, significant uncertainties remain surrounding the potential impacts of slurry amended with biological additives on carbon (C) partitioning within three pools: respired CO2, microbial biomass C (Cmic) and C retained in the soil, as well as composition of the microbial community in temperate grassland soils. We examined how slurry that has received a biological additive ultimately affects the partitioning of C within these pools and the composition of the soil microbial community, based on phospholipid fatty acid (PLFA) analysis. Four short-term incubations in which soil collected from a grassland field that has received livestock slurry treated with a commercial biological additive, alongside 14C-labelled carbohydrates of different complexity (14C-glucose, 14C-glucose 6-phosphate (G6P), and 14C-cellulose) were undertaken. Our results indicate that the addition of slurry to soil alongside carbohydrate compounds led to lower 14C biomass uptake and cumulative respiration of carbohydrate compounds, as well as greater residual 14C activities in soil, compared to the treatments in which slurry was not applied. A dominance of bacteria over fungi characterised soil microbial community composition in all treatments through time, with a prevalence of gram-negative over gram-positive bacteria. Our results also indicate that the addition of biological additives during slurry storage increased 14C biomass uptake following application of slurry to agricultural grasslands. Therefore, biological additives have the potential to create a favourable environment for maintaining and increasing soil fertility through modification of the microbial community associated with the slurry and influence of the soil microflora.

Laura A. Basile, Viviana C. Lepek

Microbial Biotechnology • 2021

Summary The specific interaction between rhizobia and legume roots leads to the development of a highly regulated process called nodulation, by which the atmospheric nitrogen is converted into an assimilable plant nutrient. This capacity is the basis for the use of bacterial inoculants for field crop cultivation. Legume plants have acquired tools that allow the entry of compatible bacteria. Likewise, plants can impose sanctions against the maintenance of nodules occupied by rhizobia with low nitrogen‐fixing capacity. At the same time, bacteria must overcome different obstacles posed first by the environment and then by the legume. The present review describes the mechanisms involved in the regulation of the entire legume–rhizobium symbiotic process and the strategies and tools of bacteria for reaching the nitrogen‐fixing state inside the nodule. Also, we revised different approaches to improve the nodulation process for a better crop yield.

DJ Walker, AR Egan, CJ Nader et al.

Australian Journal of Agricultural Research • 1975

Microbial protein synthesis in the rumen of mature sheep was measured by a technique dependent upon the incorporation of 35S from radioactive sulphate into microbial sulphur amino acids. In two separate experiments, sheep were fed on four dried forages and three fresh forages. Mean values and standard deviations for microbial protein synthesis per mole of volatile fatty acid produced in the rumen were 16.1 ? 3.4 g and 20.4? 2.3 g for dried and fresh forages respectively. Corresponding values for microbial protein synthesized per 100 g of organic matter digested in the rumen were 15.1 ? 3.6 g and 24.6 ? 4.9 g. Turnover constants for microbial protein were 1.06 ? 0.12 day-1 and 1.42 ? 0.10 day-1 when dried and fresh forages respectively were eaten, and it is suggested that efficiency of microbial protein synthesis was dependent on the rate of digesta flow through the rumen. Of the non-ammonia nitrogen (NAN) reaching the duodenum up to 41, 53 and 68% was non-microbial in origin when perennial ryegrass, Tama ryegrass and white clover respectively were eaten fresh-cut. When either subterranean clover hay, lucerne hay, wheaten hay or a mixture of wheaten hay plus wheat straw was eaten, up to 67, 57, 52 and 57% respectively of NAN at the duodenum was non-microbial in origin. In the latter two cases, the total flow of NAN was relatively low but the apparent digestibility of the non-microbial fraction in the intestines was still appreciable.

Dani Or, Shmulik Friedman, Jeanette Norton

• 2002

experimental methods for quantifying effects of water content and other dynamic environmental factors on bacterial growth in partially-saturated soils. Towards this end we reviewed critically the relevant scientific literature and performed theoretical and experimental studies of bacterial growth and activity in modeled, idealized and real unsaturated soils. The natural wetting-drying cycles common to agricultural soils affect water content and liquid organization resulting in fragmentation of aquatic habitats and limit hydraulic connections. Consequently, substrate diffusion pathways to soil microbial communities become limiting and reduce nutrient fluxes, microbial growth, and mobility. Key elements that govern the extent and manifestation of such ubiquitous interactions include characteristics of diffusion pathways and pore space, the timing, duration, and extent of environmental perturbations, the nature of microbiological adjustments (short-term and longterm), and spatial distribution and properties of EPS clusters (microcolonies). Of these key elements we have chosen to focus on a manageable subset namely on modeling microbial growth and coexistence on simple rough surfaces, and experiments on bacterial growth in variably saturated sand samples and columns. Our extensive review paper providing a definitive “snap-shot” of present scientific understanding of microbial behavior in unsaturated soils revealed a lack of modeling tools that are essential for enhanced predictability of microbial processes in soils. We therefore embarked on two pronged approach of development of simple microbial growth models based on diffusion-reaction principles to incorporate key controls for microbial activity in soils such as diffusion coefficients and temporal variations in soil water content (and related substrate diffusion rates), and development of new methodologies in support of experiments on microbial growth in simple and observable porous media under controlled water status conditions. Experimental efforts led to a series of microbial growth experiments in granular media under variable saturation and ambient conditions, and introduction of atomic force microscopy (AFM) and confocal scanning laser microscopy (CSLM) to study cell size, morphology and multi-cell arrangement at a high resolution from growth experiments in various porous media. The modeling efforts elucidated important links between unsaturated conditions and microbial coexistence which is believed to support the unparallel diversity found in soils. We examined the role of spatial and temporal variation in hydration conditions (such as exist in agricultural soils) on local growth rates and on interactions between two competing microbial species. Interestingly, the complexity of soil spaces and aquatic niches are necessary for supporting a rich microbial diversity and the wide array of microbial functions in unsaturated soils. This project supported collaboration between soil physicists and soil microbiologist that is absolutely essential for making progress in both disciplines. It provided a few basic tools (models, parameterization) for guiding future experiments and for gathering key information necessary for prediction of biological processes in agricultural soils. The project sparked a series of ongoing studies (at DTU and EPFL and in the ARO) into effects of soil hydration dynamics on microbial survival strategy under short term and prolonged desiccation (important for general scientific and agricultural applications).

, Mark C. Trimmer

Burleigh Dodds Series in Agricultural Science • 2021

This chapter focuses on microbial bioprotectants and the marketplace. The chapter begins by first discussing the latest figure in terms of microbial bioprotectants global market value. It also highlights the different types and ways these bioprotectants can be used. The chapter also discusses the trends and drivers in the microbial market, focusing specifically on why microbials dominate and the factors that drive bioprotectant adoption. A section on the myths about the bioprotectant market is also included, which is then followed by a discussion of the limitations for using microbial bioprotectants. Future opportunities and threats for microbial bioprotectants are also highlighted.

, Pimonpan Pakdee

• 2020

The diversity of soil microbial communities are the main factors in the biogeochemical cycles due to their ability to control underground activities, meanwhile the disturbed soils from agricultural practices often perturb microbial communities. This study aims to 1) investigate the microbial diversity in agricultural soils. 2) determine the relationships between the relative abundance of microbes and soil environmental factors such as pH, organic matter (OM) , electrical conductivity (EC), nitrogen (N) and available phosphorus (P) in the agricultural soil of Saraburi. Thirty soil samples at 15 cm depth were collected from agricultural soil in thirty sub-districts of Saraburi Province in August 2020. Three diversity indices indicated microbial diversity as follows: 1.77 for Shannon diversity index (H’), 0.74 for Simpson's diversity index, and 0.19 for Evenness index. Principal component analysis (PCA) was conducted to observed the relationship between Shannon's diversity index of microbial communities and soil properties. Shannon's diversity index correlated with available P in a positive direction and negative correlation with pH, EC and OM. Canonical correspondence analysis (CCA) determined the relationship between soil microbial communities and soil properties. The phyla Firmicutes (26.9%), Proteobacteria (16.9%), Bacteroidetes (16.8%), Acidobacteria (11.5%), and Actinobacteria (8.3%) were abundant in all soil samples. Firmicutes was a positive correlation with soil pH, OM, and EC, this phylum also shows the negative correlation between N and available P. Proteobacteria were positive correlation with both nutrients. Bacteroidetes was positive significant correlation with EC and OM. Acidobacteria indicating that a strong positive correlation with available P and negative correlation with OM. Actinobacteria was negatively correlated with soil pH. The findings indicated that soil properties influence on the microbial community. The distribution of microbial communities and relationships with environmental factors could help farmers for balancing fertilizer application of soil improvement.

Alejandra Bravo, Mario Soberón

Microbial Biotechnology • 2023

Abstract Extensive use of chemical insecticides to control insect pests in agriculture has improved yields and production of high‐quality food products. However, chemical insecticides have been shown to be harmful also to beneficial insects and many other organisms like vertebrates. Thus, there is a need to replace those chemical insecticides by other control methods in order to protect the environment. Insect pest pathogens, like bacteria, viruses or fungi, are interesting alternatives for production of microbial‐based insecticides to replace the use of chemical products in agriculture. Organic farming, which does not use chemical pesticides for pest control, relies on integrated pest management techniques and in the use of microbial‐based insecticides for pest control. Microbial‐based insecticides require precise formulation and extensive monitoring of insect pests, since they are highly specific for certain insect pests and in general are more effective for larval young instars. Here, we analyse the possibility of using microbial‐based insecticides to replace chemical pesticides in agricultural production.

Tucker R. Burch, J. Stokdyk, A. Firnstahl et al.

Journal of Environmental Quality • 2022

Antimicrobial resistance is a growing public health problem that requires an integrated approach among human, agricultural, and environmental sectors. However, few studies address all three components simultaneously. We investigated the occurrence of five antibiotic resistance genes (ARGs) and the class 1 integron gene (intI1) in private wells drawing water from a vulnerable aquifer influenced by residential septic systems and land-applied dairy manure. Samples (n = 138) were collected across four seasons from a randomized sample of private wells in Kewaunee County, Wisconsin. Measurements of ARGs and intI1 were related to microbial source tracking (MST) markers specific to human and bovine feces; they were also related to 54 risk factors for contamination representing land use, rainfall, hydrogeology, and well construction. ARGs and intI1 occurred in 5-40% of samples depending on target. Detection frequencies for ARGs and intI1 were lowest in the absence of human and bovine MST markers (1-30%), highest when co-occurring with human and bovine markers together (11-78%), and intermediate when co-occurring with just one type of MST marker (4-46%). Gene targets were associated with septic system density more often than agricultural land, potentially because of the variable presence of manure on the landscape. Determining ARG prevalence in a rural setting with mixed land use allowed an assessment of the relative contribution of human and bovine fecal sources. Because fecal sources co-occurred with ARGs at similar rates, interventions intended to reduce ARG occurrence may be most effective if both sources are considered. This article is protected by copyright. All rights reserved.

J. Mori, R. Smith

Risk Analysis • 2022

The conservation of freshwater is of both global and national importance, and in the United States, agriculture is one of the largest consumers of this resource. Reduction of the strain farming puts on local surface or groundwater is vital for ensuring resilience in the face of climate change, and one possible option is to irrigate with a combination of freshwater and reclaimed water from municipal wastewater treatment facilities. However, this wastewater can contain pathogens that are harmful to human health, such as Legionella pneumophila, which is a bacterium that can survive aerosolization and airborne transportation and cause severe pneumonia when inhaled. To assess an individual adult's risk of infection with L. pneumophila from a single exposure to agricultural spray irrigation, a quantitative microbial risk assessment was conducted for a scenario of spray irrigation in central Illinois, for the growing seasons in 2017, 2018, and 2019. The assessment found that the mean risk of infection for a single exposure exceeded the safety threshold of 10–6 infections/exposure up to 1 km from a low‐pressure irrigator and up to 2 km from a high‐pressure irrigator, although no median risk exceeded the threshold for any distance or irrigator pressure. These findings suggest that spray irrigation with treated municipal wastewater could be a viable option for reducing freshwater consumption in Midwest farming, as long as irrigation on windy days is avoided and close proximity to the active irrigator is limited.

J. Pekkanen, P. Kirjavainen, M. Sulyok et al.

ISEE Conference Abstracts • 2013

Background:Toxic secondary microbial metabolites have been suggested to contribute to the adverse respiratory effects of mold and moisture damage. Aims: The aim of this study was to comprehensively...

P. Pollegioni, C. Mattioni, Martina Ristorini et al.

Atmosphere • 2022

Biogenic fraction of airborne PM10 which includes bacteria, viruses, fungi and pollens, has been proposed as one of the potential causes of the PM10 toxicity. The present study aimed to provide a comprehensive understanding of the microbial community variations associated to PM10, and their main local sources in the surrounding environment in three urban sites of Rome, characterized by differential pollution rate: green area, residential area and polluted area close to the traffic roads. We combined high-throughput amplicon sequencing of the bacterial 16S rRNA gene and the fungal internal transcribed spacer (ITS) region, with detailed chemical analysis of particulate matter sampled from air, paved road surfaces and leaf surfaces of Quercus ilex. Our results demonstrated that bacterial and fungal airborne communities were characterized by the highest alpha-diversity and grouped separately from epiphytic and road dust communities. The reconstruction of source-sink relationships revealed that the resuspension/deposition of road dust from traffic might contribute to the maximum magnitude of microbial exchanges. The relative abundance of extremotolerant microbes was found to be enhanced in epiphytic communities and was associated to a progressively increase of pollution levels as well as opportunistic human pathogenicity in fungal communities.

Yuwei Pan, Jiawei Xie, Weixing Yan et al.

SSRN Electronic Journal • 2022

Nutrients and heavy metals (HM) in the sediment have an impact on microbial diversity and community structure. In this study, the distribution characteristics of nutrients, HM, and microbial community in the sediments along the Longsha River, a tributary of the Pearl River (or Zhu Jiang), China were investigated by analyzing samples from 11 sites. On the basis of the HM-contamination level, the 11 sampling sites were divided into three groups to explore the changes in microbial communities at different ecological risk levels. Results indicated that nutrient concentrations were higher near farmlands and residential lands, while the ecological risk of HM at the 11 sampling sites was from high to low as S10 > S2 > S9 > S6 > S11 > S7 > S5 > S8 > S3 > S4 > S1. Among these HM, Cu, Cr, and Ni had intense ecological risks. In addition, the results of Variance Partitioning Analysis (VPA) revealed a higher contribution of HM (35.93%) to microbial community variation than nutrients (12.08%) and pH (4.08%). Furthermore, the HM-tolerant microbial taxa (Clostridium_sensu_stricto_1, Romboutsia, norank_o__Gaiellales, and etc.) were the dominant genera, and they were more dynamic around industrial lands, while microbes involved in the C, N, and S cycles (e.g., Smithella, Thiobacillus, Dechloromonas, Bacter oidetes_vadinHA17, and Syntrophorhabdus) were inhibited by HM, while their abundance was lower near industrial lands and highway but higher around residential lands. A three-unit monitoring program of land-use types, pollutants, and microbial communities was proposed. These results provide a new perspective on the control of riparian land-use types based on contaminants and microbes, and different microbial community response patterns may provide a reference for contaminant control in sediments with intensive industrial activities.

S. Vosloo, L. Huo, Umang Chauhan et al.

Environmental Science & Technology • 2023

COVID-19 pandemic-related building restrictions heightened drinking water microbiological safety concerns post-reopening due to the unprecedented nature of commercial building closures. Starting with phased reopening (i.e., June 2020), we sampled drinking water for 6 months from three commercial buildings with reduced water usage and four occupied residential households. Samples were analyzed using flow cytometry and full-length 16S rRNA gene sequencing along with comprehensive water chemistry characterization. Prolonged building closures resulted in 10-fold higher microbial cell counts in the commercial buildings [(2.95 ± 3.67) × 105 cells mL–1] than in residential households [(1.11 ± 0.58) × 104 cells mL–1] with majority intact cells. While flushing reduced cell counts and increased disinfection residuals, microbial communities in commercial buildings remained distinct from those in residential households on the basis of flow cytometric fingerprinting [Bray–Curtis dissimilarity (dBC) = 0.33 ± 0.07] and 16S rRNA gene sequencing (dBC = 0.72 ± 0.20). An increase in water demand post-reopening resulted in gradual convergence in microbial communities in water samples collected from commercial buildings and residential households. Overall, we find that the gradual recovery of water demand played a key role in the recovery of building plumbing-associated microbial communities as compared to short-term flushing after extended periods of reduced water demand.

Vicente Gomez-Alvarez, Hodon Ryu, Min Tang et al.

Frontiers in Microbiology • 2023

Opportunistic premise plumbing pathogens (OPPPs) have been detected in buildings’ plumbing systems causing waterborne disease outbreaks in the United States. In this study, we monitored the occurrence of OPPPs along with free-living amoeba (FLA) and investigated the effects of residential activities in a simulated home plumbing system (HPS). Water samples were collected from various locations in the HPS and analyzed for three major OPPPs: Legionella pneumophila, nontuberculous mycobacterial species (e.g., Mycobacterium avium, M. intracellulare, and M. abscessus), and Pseudomonas aeruginosa along with two groups of amoebas (Acanthamoeba and Vermamoeba vermiformis). A metagenomic approach was also used to further characterize the microbial communities. Results show that the microbial community is highly diverse with evidence of spatial and temporal structuring influenced by environmental conditions. L. pneumophila was the most prevalent pathogen (86% of samples), followed by M. intracellulare (66%) and P. aeruginosa (21%). Interestingly, M. avium and M. abscessus were not detected in any samples. The data revealed a relatively low prevalence of Acanthamoeba spp. (4%), while V. vermiformis was widely detected (81%) across all the sampling locations within the HPS. Locations with a high concentration of L. pneumophila and M. intracellulare coincided with the highest detection of V. vermiformis, suggesting the potential growth of both populations within FLA and additional protection in drinking water. After a period of stagnation lasting at least 2-weeks, the concentrations of OPPPs and amoeba immediately increased and then decreased gradually back to the baseline. Furthermore, monitoring the microbial population after drainage of the hot water tank and partial drainage of the entire HPS demonstrated no significant mitigation of the selected OPPPs. This study demonstrates that these organisms can adjust to their environment during such events and may survive in biofilms and/or grow within FLA, protecting them from stressors in the supplied water.

Mohamed Shehata, Samir M Zaid, S. T. Al-Goul et al.

Scientific Reports • 2024

Groundwater is an excellent alternative to freshwater for drinking, irrigation, and developing arid regions. Agricultural, commercial, industrial, residential, and municipal activities may affect groundwater quantity and quality. Therefore, we aimed to use advanced methods/techniques to monitor the piezometric levels and collect groundwater samples to test their physicochemical and biological characteristics. Our results using software programs showed two main types of groundwater: the most prevalent was the Na–Cl type, which accounts for 94% of the groundwater samples, whereas the Mg–Cl type was found in 6% of samples only. In general, the hydraulic gradient values, ranging from medium to low, could be attributed to the slow movement of groundwater. Salinity distribution in groundwater maps varied between 238 and 1350 mg L−1. Although lower salinity values were observed in northwestern wells, higher values were recorded in southern ones. The collected seventeen water samples exhibited brackish characteristics and were subjected to microbial growth monitoring. Sample WD12 had the lowest total bacterial count (TBC) of 4.8 ± 0.9 colony forming unit (CFU mg L−1), while WD14 had the highest TBC (7.5 ± 0.5 CFU mg L−1). None of the tested water samples, however, contained pathogenic microorganisms. In conclusion, the current simulation models for groundwater drawdown of the Quaternary aquifer system predict a considerable drawdown of water levels over the next 10, 20, and 30 years with the continuous development of the region.

Mansi Bansal, Nidhi Seth, C. R. Babu et al.

Journal of Water and Health • 2024

Diverse bacterial assemblages were identified in a large, open stormwater drain (vernacular: nalah) built decades ago in a densely populated suburb of Delhi, India. Illumina-based next-generation sequencing (NGS) of 16S rRNA gene amplicons was conducted with metagenomic DNAs isolated from influent sewage water and sediment samples collected from Sahibabad drain, which now carries domestic and industrial wastes to downstream sewage treatment plants. Results are discussed with respect to diversity and adaptation to unique ecological niche(s) in these drains as well as the prevalence of potentially pathogenic bacteria. Recently, it has become a common practice to cover such drains with thick cement slabs to facilitate the construction of residential/commercial complexes. However, the impact of concrete covers on microbial communities that inhabit the Sahibabad drain is unknown. Results indicated that open drains with better aeration and exposure to sunlight contained microbes that likely enhance biodegradation in sewage water. The deposition of sediments along the course of the drain was dominated by methanogenic and sulphidogenic bacteria. Covering of the drain may have contributed to an increased abundance of anaerobic pathogens which settled in sediments and/or resuspended into sewage water. Such findings are important as the microbes active in sewage can impact public health and drain infrastructure.

K. Nkongolo, John B Mukalay, Antoine K. Lubobo et al.

Microorganisms • 2024

The mining industry in the copper belt region of Africa was initiated in the early 1900s, with copper being the main ore extracted to date. The main objectives of the present study are (1) to characterize the microbial structure, abundance, and diversity in different ecological conditions in the cupriferous city of Lubumbashi and (2) to assess the metal phytoextraction potential of Leucaena leucocephala, a main plant species used in tailing. Four ecologically different sites were selected. They include a residential area (site 1), an agricultural dry field (site 2), and an agricultural wetland (site 3), all located within the vicinity of a copper/cobalt mining plant. A remediated tailing was also added as a highly stressed area (site 4). As expected, the highest levels of copper and cobalt among the sites studied were found at the remediated tailing, with 9447 mg/kg and 2228 mg/kg for copper and cobalt, respectively. The levels of these metals at the other sites were low, varying from 41 mg/kg to 579 mg/kg for copper and from 4 mg/kg to 110 mg/kg for cobalt. Interestingly, this study revealed that the Leucaena leucocephala grown on the remediated sites is a copper/cobalt excluder species as it accumulates soil bioavailable metals from the rhizosphere in its roots. Amplicon sequence analysis showed significant differences among the sites in bacterial and fungal composition and abundance. Site-specific genera were identified. Acidibacter was the most abundant bacterial genus in the residential and remediated tailing sites, with 11.1% and 4.4%, respectively. Bacillus was predominant in both dry (19.3%) and wet agricultural lands (4.8%). For fungi, Fusarium exhibited the highest proportion of the fungal genera at all the sites, with a relative abundance ranging from 15.6% to 20.3%. Shannon diversity entropy indices were high and similar, ranging from 8.3 to 9 for bacteria and 7.0 and 7.4 for fungi. Β diversity analysis confirmed the closeness of the four sites regardless of the environmental conditions. This lack of differences in the microbial community diversity and structures among the sites suggests microbial resilience and physiological adaptations.

Helen Y. Buse, Jatin H. Mistry

PLOS Water • 2024

A strategy for nitrification control within chloraminated drinking water systems (CDWSs) is to temporarily switch from chloramine secondary disinfection to free chlorine, also known as a free chlorine conversion (FCC). However, the long-term and beneficial effects of FCCs are unclear, especially regarding opportunistic pathogen occurrence. In this study, the impacts to microbial and physicochemical parameters were monitored throughout a CDWS implementing a FCC. Water samples were collected weekly for 4–6 weeks before, during, and after a FCC at eight locations: four distribution system and four residential sites. Monochloramine residual (mean±standard deviation) before and after the FCC averaged 1.8±0.9 and 1.6±1.0 parts per million (ppm) for all sites, respectively. Free chlorine levels averaged 2.3±0.9 ppm. There were no significant differences in turbidity and hardness at each location during the three time periods, but some were noted for pH, temperature, and orthophosphate levels across various sites and sampling periods. For all locations, heterotrophic plate count levels were lower during the FCC compared to the periods before and after. All samples from one residence were culture positive for P. aeruginosa which exhibited high levels before the FCC, decreasing levels during, and steadily increasing levels after. Additionally, one week prior to the FCC, sediment samples from two elevated storage tanks, ET-1 and ET-2, were analyzed with ET-1 displaying higher levels of culturable heterotrophic bacteria and molecularly detected total bacteria, Legionella spp., and nontuberculous mycobacteria (NTM), as well as presence of culturable P. aeruginosa and total coliforms compared to ET-2. Fourteen P. aeruginosa and total coliform isolates were whole genome sequenced with genetic differences observed depending on the sampling location and timepoint. Collectively, the observed differences in chemical and microbial parameters advocates for a better understanding of the effects associated with implementing FCCs to determine both their effectiveness and potential risks/rewards to water quality.

C. Medriano, Amabel Chan, R. De Sotto et al.

SSRN Electronic Journal • 2023

Anthropogenic activities have led to unexpected changes in microbial community composition and structure, resulting in an interruption of soil ecological roles in urban environments. We questioned the impact of the different land use (e.g., agricultural, industrial, recreational, coastal, and residential areas) on the distribution of nitrifying bacteria and microbial interaction in a tropical soil. The dominant nitrifying bacteria were ammonia-oxidizing archaea (AOA) in tropical soils up to 107 copies/g of soil, while the abundance of ammonia-oxidizing bacteria (AOB) was significantly higher in agricultural soil only. Comammox (CMX) was ubiquitous up to 105 copies/g of tropical soil, indicating that CMX might share ecological niches with AOA and considerably contribute to nitrification in urban areas. The most abundant phylum is Actinobacteria, accounting for 27-34 % relative abundance among most land-use types, but Proteobacteria was observed as the most prevalent phylum in agricultural soil. The physicochemical properties (e.g., soil pH and nutrient contents) of different types of land use influenced microbial richness and diversities associated with nitrogen cycling. Multivariate analysis disclosed that agricultural soils were distinct from other land uses because of the concentrations of nutrient and heavy metal and the abundance of microorganisms associated with nitrogen cycles. Also, the microbial co-occurrence network revealed that agricultural soils were a highly interconnected network of the microbial community. In this study, C: N ratio might have a significant impact on ecological networks and the abundance of nitrogen-related taxa, which could influence microbial interactions and complexity in tropical soils. Thus, the impact of anthropogenic land use induced the changes in microbial composition and diversity, co-occurrence network, and nitrifying bacteria, leading to potential transformation in ecological services of tropical soils and nitrogen cycling in urban environments.

Xianqin Yang, C. Narváez‐Bravo, Peipei Zhang

Frontiers in Microbiology • 2024

Meat production is a complex system, continually receiving animals, water, air, and workers, all of which serve as carriers of bacteria. Selective pressures involved in different meat processing stages such as antimicrobial interventions and low temperatures, may promote the accumulation of certain residential microbiota in meat cutting facilities. Bacteria including human pathogens from all these sources can contaminate meat surfaces. While significant advancements have been made in enhancing hygienic standards and pathogen control measures in meat plants, resulting in a notable reduction in STEC recalls and clinical cases, STEC still stands as a predominant contributor to foodborne illnesses associated with beef and occasionally with pork. The second-and third-generation sequencing technology has become popular in microbiota related studies and provided a better image of the microbial community in the meat processing environments. In this article, we reviewed the potential factors influencing the microbial ecology in commercial meat processing facilities and conducted a meta-analysis on the microbiota data published in the last 10 years. In addition, the mechanisms by which bacteria persist in meat production environments have been discussed with a focus on the significant human pathogen E. coli O157:H7 and generic E. coli, an indicator often used for the hygienic condition in food production.

Yi-Dan Zhang, S. Fan, Zhengfang Zhang et al.

Environmental Health Perspectives • 2023

Background: Greenness, referring to a measurement of the density of vegetated land (e.g., gardens, parks, grasslands), has been linked with many human health outcomes. However, the evidence on greenness exposure and human microbiota remains limited, inconclusive, drawn from specific regions, and based on only modest sample size. Objectives: We aimed to study the association between greenness exposure and human microbial diversity and composition in a large sample across 34 countries and regions. Methods: We explored associations between residential greenness and human microbial alpha-diversity, composition, and genus abundance using data from 34 countries. Greenness exposure was assessed using the normalized difference vegetation index and the enhanced vegetation index mean values in the month before sampling. We used linear regression models to estimate the association between greenness and microbial alpha-diversity and tested the effect modification of age, sex, climate zone, and pet ownership of participants. Differences in microbial composition were tested by permutational multivariate analysis of variance based on Bray–Curtis distance and differential taxa were detected using the DESeq2 R package between two greenness exposure groups split by median values of greenness. Results: We found that higher greenness was significantly associated with greater richness levels in the palm and gut microbiota but decreased evenness in the gut microbiota. Pet ownership and climate zone modified some associations between greenness and alpha-diversity. Palm and gut microbial composition at the genus level also varied by greenness. Higher abundances of the genera Lactobacillus and Bifidobacterium, and lower abundances of the genera Anaerotruncus and Streptococcus, were observed in people with higher greenness levels. Discussion: These findings suggest that residential greenness was associated with microbial richness and composition in the human skin and gut samples, collected across different geographic contexts. Future studies may validate the observed associations and determine whether they correspond to improvements in human health. https://doi.org/10.1289/EHP12186

Ruomei Xu, Grace C. McLoughlin, Mark P. Nicol et al.

Microorganisms • 2024

The existence of the human milk microbiome has been widely recognized for almost two decades, with many studies examining its composition and relationship to maternal and infant health. However, the richness and viability of the human milk microbiota is surprisingly low. Given that the lactating mammary gland houses a warm and nutrient-rich environment and is in contact with the external environment, it may be expected that the lactating mammary gland would contain a high biomass microbiome. This discrepancy raises the question of whether the bacteria in milk come from true microbial colonization in the mammary gland (“residents”) or are merely the result of constant influx from other bacterial sources (“tourists”). By drawing together data from animal, in vitro, and human studies, this review will examine the question of whether the lactating mammary gland is colonized by a residential microbiome.

Myrna M. T. de Rooij, G. Hoek, H. Schmitt et al.

Environmental Science & Technology • 2019

Microbial air pollution from livestock farms has raised concerns regarding public health. Little is known about airborne livestock-related microbial levels in residential areas. We aimed to increase insights into this issue. Air measurements were performed in 2014 and 2015 at 61 residential sites in The Netherlands. Quantitative-PCR was used to assess DNA concentrations of selected bacteria (commensals: Escherichia coli and Staphylococcus spp.; a zoonotic pathogen: Campylobacter jejuni) and antimicrobial resistance (AMR) genes (tetW, mecA) in airborne dust. Mixed models were used to explore spatial associations (temporal adjusted) with livestock-related characteristics of the surroundings. DNA from commensals and AMR genes was detectable even at sites furthest away from farms (1200 m), albeit at lower levels. Concentrations, distinctly different between sites, were strongly associated with the density of farms in the surroundings especially with poultry and pigs. C. jejuni DNA was less prevalent (42% of samples positive). Presence of C. jejuni was solely associated with poultry (OR: 4.7 (95% CI: 1.7–14), high versus low poultry density). Residential exposure to livestock-related bacteria and AMR genes was demonstrated. Identified associations suggest contribution of livestock farms to microbial air pollution in general and attribution differences between farm types. This supports the plausibility of recent studies showing health effects in relation to residential proximity to farms.