Jenifar Das, Ashish Kumar Singh

bioRxiv (Cold Spring Harbor Laboratory) • 2024

Abstract Due to the adverse effects of synthetic colours on human health and the environment, there is a rapid shift towards the use of colours from natural sources like plants and microorganisms. Many pigment-producing microorganisms are identified and isolated from extreme environments like glaciers, ice cores, marine surface waters, etc. In this study, we have isolated 4 distinct pigment-producing bacterial strains from an Arctic stone sample collected from the vicinity of the Indian Research Station Himadri (78°55 ′ N 11°56 ′ E ), located at the International Arctic Research Base, NyÅlesund, Svalbard, Norway. Pigment production was optimised by identifying the right growth medium, temperature, pH, and incubation period. The morphological, cultural, and biochemical characteristics were identified using several experiments like Gram Staining, Catalase Test, Oxydative-Fermentative Test, etc. The objective of this study is to identify novel bacterial strains capable of producing distinct pigments for pharmaceutical and industrial applications.

Mehwish Saleem, Zunaira Azam, Saneela Kausar et al.

Pakistan BioMedical Journal • 2022

The term antimicrobial resistance refers to the ability to resist the effects of drugs formally used to treat them and this term relates only to bacteria becoming resistant. Microorganisms which are resistant to multiple drugs are known as multidrug resistant bacteria. Methods: Most of the experimental work to study the application of E-Test for detection of lactamase producing bacteria was carried out at Pathology Laboratory of Sir Ganga Ram Hospital Lahore. While the remaining research work was done in Microbiology Laboratory of Govt. Post Graduate Islamia College Cooper Road Lahore during the study period from December 2019 to March 2020. Total 60 samples of different patients were collected from Sir Ganga Ram Hospital Lahore and most of the samples were urine (n=25), followed by Blood (n=14), Pus (n=14), and sputum (n=7). Oxidase, indole, citrate utilization, sugar fermentation (Kligler iron agar medium) and urease tests were performed for the identification bacterial strains. Results: In all of 60 samples frequency of occurrence of E. coli, Enterobacter and Klebsiella strains were 59%, 23%, 18% respectively. Most of them (n=36) were ESBLs positive and about (n=24) were ESBLs negative and their percentage were 60% and 40% respectively. Extended spectrum β-lactamase (ESBL) producing strains of Enterobacteriaceae have now become as a significant issue in hospitalized and community patients. These microorganisms are liable for many diseases, for example, urinary tract infection, septicemia, hospitalized-acquired pneumonia, intra-abdominal abscess, brain abscess and device related infections. Conclusions: The frequency of ESBL producing bacteria in most hospitals is very high especially in the hospitals where broad spectrum antibiotics are generally recommended. Among gram negative bacteria, the emergence of resistance to expanded spectrum cephalosporins has been a major concern. Many of ESBL producing bacteria showed multidrug resistance.

Yong Yang, Olga Babich, Stanislav Sukhikh et al.

Foods and Raw Materials • 2020

Introduction. Increased resistance of microorganisms to traditional antibiotics has created a practical need for isolating and synthesizing new antibiotics. We aimed to study the antibiotic activity and resistance of bacteriocins produced by lactic acid bacteria and other microorganisms.
 Study objects and methods. We studied the isolates of the following microorganism strains: Bacillus subtilis, Penicillium glabrum, Penicillium lagena, Pseudomonas koreenis, Penicillium ochrochloron, Leuconostoc lactis, Lactobacillus plantarum, Leuconostoc mesenteroides, Pediococcus acidilactici, Leuconostoc mesenteroides, Pediococcus pentosaceus, Lactobacillus casei, Lactobacillus fermentum, Bacteroides hypermegas, Bacteroides ruminicola, Pediococcus damnosus, Bacteroides paurosaccharolyticus, Halobacillus profundi, Geobacillus stearothermophilus, and Bacillus caldotenax. Pathogenic test strains included Escherichia coli, Salmonella enterica, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus mycoides, Alcaligenes faecalis, and Proteus vulgaris. The titer of microorganisms was determined by optical density measurements at 595 nm. 
 Results and discussion. We found that eleven microorganisms out of twenty showed high antimicrobial activity against all test strains of pathogenic and opportunistic microorganisms. All the Bacteroides strains exhibited little antimicrobial activity against Gramnegative test strains, while Halobacillus profundi had an inhibitory effect on Gram-positive species only. The Penicillium strains also displayed a slight antimicrobial effect on pathogenic test strains.
 Conclusion. The antibiotic resistance of the studied lactic acid bacteria and other bacteriocin-producing microorganisms allows for their use in the production of pharmaceutical antibiotic drugs.

M Saiful Islam, Naima Moazzem, M Abdullah Yusuf et al.

Journal of Current and Advance Medical Research • 2014

Emergence of bacterial resistance causes limitation of the action of antimicrobial agents. Frequency of extended spectrum ?-Lactamase (ESBL) production is high among Escherichia coli (E. coli) and Klebsiella species. This has created a worldwide problem resulting in treatment failure. ESBLs have become widespread throughout the world. Microbes undergo mutation of genes, which can spread from cell to cell by mobile genetic elements such as plasmids, transposons and bacteriophages. Resistant bacteria flourish in areas of heavy antibiotic use such as hospitals and ICU. With widespread use of antibiotic, the frequency of penicillinase producing staphylococci increased. The availability of the second-generation cephalosporin, such as cefamondole, cefoxitin, and cefuroxime, or 3rd generation cephalosporin, such as cefotaxime, ceftazidime, ceftriaxone has been the leading cause of potential resistances in nosocomial Gram-negative bacilli. Hospital outbreaks of multi-drug resistant Enterobacteriaceae are now being frequently caused by extended spectrum beta-lactamase (ESBL) producers. Incidence of ESBL producing strains among clinical isolates has been steadily increasing over past years resulting in limitation of therapeutic options. Bacterial antibiotic resistance has become a major clinical concern worldwide including Bangladesh. Recently, the use of second and third generation cephalosporin has led to the selection of Gram-negative organisms resistant to ?-lactamase stable cephalosporin. This resistance is attributed to the production of extended spectrum ?-lactamases.DOI: http://dx.doi.org/10.3329/jcamr.v1i1.19560J Curr Adv Med Res 2014;1(1):13-19

L Advinda, Anhar, Irdawati

Journal of Physics: Conference Series • 2021

Abstract Siderophore is a chemical compound of Fe chelating. This compound is produced by several microorganisms that grow under iron-limiting conditions. Siderophore can facilitate the transfer of Fe from the environment to become available to plants. The siderophore ability to bind Fe as a competitor against other microorganisms, so that in the agricultural system it can be used as a plant disease controller. This study aims to determine the production of siderophore produced by several fluorescent pseudomonad isolates and its antagonistic tests against Blood Disease Bacteria (BDB). Siderohore detection is determined by the absorbance value obtained, and measured using a spectrophotometer at a wavelength of 410 nm. The antagonist test used a completely randomized designwith 7 treatments and 3 replications. The treatment is fluorescent pseudomonads isolates PfLAHP2, PfPb1, PfCas3, PfKd7, PfCas, PfPj1, and PfPj2. PfLAHP2 isolates produced the highest siderophore, which was 1.027, and the lowest isolate PfCas was 0.148. The antagonistic test of fluorescent pseudomonad against BDB showed that PfLAHP2 isolate produced the largest inhibitory zone, which was 1.042 cm.

Matthew I Hutchings, Barrie Wilkinson

Microbiota and Host • 2023

Many, if not all, plants and animals form mutually beneficial symbioses (mutualisms) with microbes and a subset of these mutualisms are defensive, in which the host provides food and housing in return for defence against disease. These symbioses typically involve antibiotic-producing bacteria, the best known of which are filamentous actinomycetes in the genera Streptomyces and Pseudonocardia and unicellular species in the genus Pseudomonas. Such mutualisms are likely to be widespread in nature, but they are best characterised in insects, which provide experimentally tractable models for studying symbiosis and microbiome formation because they typically host less complex microbial communities. Here, we examine the mutualisms formed between insects and antibiotic-producing bacteria using well-characterised examples, including digger wasps and their endosymbiotic Streptomyces species, attine ants and their mutualist Pseudonocardia species and Paederus beetles with their pederin-producing Pseudomonas species. We also discuss how searching such symbiotic niches can give insights into the evolution and functions of microbial specialised metabolites and provide new platforms for antibiotic discovery.

Kristie Tanner, Christian Abendrotht, Manuel Porcar

bioRxiv (Cold Spring Harbor Laboratory) • 2017

Lipases are key biocatalysts with important biotechnological applications. With the aim of isolating robust lipolytic microbial strains, we have analyzed the bacterial communities inhabiting two domestic extreme environments: a thermophilic sauna and a dishwasher filter. Scanning electron microscopy revealed biofilm-forming and scattered microorganisms in the sauna and dishwasher sample, respectively. A culture-independent approach based on 16S rRNA analysis indicated a high abundance of Proteobacteria in the sauna sample; and, a large amount of Proteobacteria, Firmicutes, Cyanobacteria and Actinobacteria in the dishwasher filter. With a culture-dependent approach, we isolated 48 bacterial strains, screened their lipolytic activities on media with tributyrin as the main carbon source, and finally selected five isolates for further characterization. These strains, all of them identified as members of the genus Bacillus, displayed optimum lipolytic peaks at pH 6.5 and with 1-2% NaCl, and the activity proved very robust at a wide range of pH (up to 11.5) and added NaCl concentrations (up to 4%). The thermal, pH and salt robustness of the selected isolates is a valuable attribute for these strains, which are promising as highly tolerant biodetergents. To our knowledge, this is the first report regarding the isolation from an indoor environment of Bacillus strains with a high potential for industry.

Ana Beatriz Souza Flor dos Santos, Manuele Figueiredo da Silva, João Xavier de Araújo-Júnior et al.

Current Drug Targets • 2021

Bacterial resistance has become a major global concern, affecting about 500, 000 individuals in 22 countries. Thus, it is clear that Gram-negative bacteria have been receiving more attention in this scenario. These bacteria perform several resistance mechanisms, such as modifying lipid A from lipopolysaccharides as a product of the mcr-1 gene expression. This gene was initially identified in animals; however, it quickly spread to humans, spreading to 70 countries. Mcr-1 gene attributes resistance to polymyxin B and colistin, which are drugs established as the last alternative to combat Enterobacteriaceae bacteria. Notwithstanding the prevalence and lack of antibiotic therapies for such bacteria, this article aimed to compile information about natural compounds against the resistance attributed by this gene, including the activity of isolated colistin or its associations with other antibiotics. Among the studies that evaluated colistin's synergistic action with other compounds, azidothymidine and isoalantholactone stood out. On the other hand, the paenipeptin 1 analog showed satisfactory activities when associated with other antibiotics. Besides, it is worth mentioning that molecular docking results between ostole and eugenol toward phosphoethanolamine transferase MCR-1 revealed that these compounds could interact with critical amino acid residues for the catalytic action of this enzyme. Based on this, natural agents' role is evident against infections caused by mcr-1-positive bacteria, directly contributing to the development of new effective pharmacotherapies.

Burak ALAYLAR, Mehmet KARADAYI

Iğdır Üniversitesi Fen Bilimleri Enstitüsü Dergisi • 2021

Plant growth promoting rhizobacteria (PGPR) have critical role in promoting plant growth and health with various mechanisms. Production of indole acetic acid (IAA) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity are well-known plant growth promoting (PGP) properties. In the current study; A total of 48 morphologically distinct bacterial colonies were chosen during the isolation of bacteria from various rhizospheric wheat, maize and sainfoin soil samples from agricultural areas in Ağrı-Turkey. The bacteria were isolated from soil samples utilizing by culture-dependent techniques. Then, the strains were visualised for PGP activities such as production acetic acid IAA and ACC deaminase activity. The 16S rRNA sequence similarity of potential PGPR rhizospheric strains demonstrated that strains belong to species Bacillus, Pseudomonas, Microbacterium, Pseudarthrobacter, Arthrobacter and Enterobacter. Totally, 11 of 48 isolates exhibited highly IAA producing and ACC deaminase activity. These results show that IAA producing and ACC deaminase activity of local potential PGPR strains isolated from soil rhizospheric which can appropriate for sustainable agricultural applications in Ağrı province.

Kalyani Pullapukuri, Gopa Dinesh Reddy

• 2023

Biosurfactant is a structurally diverse group of surface-active molecules, synthesized by microorganisms. They are capable of reducing surface and interfacial tension with low toxicity, high specificity and biodegradability. The samples were enriched in nutrient agar containing diesel oil, serially diluted and poured on nutrient agar plate. Biosurfactant producing organisms were screened by using oil spreading method, Blood hemolysis test, Emulsification index (E24) and Drop collapse method. Out of 50 isolates, ten strains showed positive biosurfactant production. Another interesting finding in this study was the use of crude oil as hydrophobic substrate for the isolation of biosurfactant producing bacterial strains; this approach may be useful during the initial isolation of biosurfactant producing bacteria to reduce the number of strains to be screened. These strains were characterized by using different biochemical tests like Gram’s staining, IMVIC etc.

Matteo Bassetti, Antonio Vena, Barbara Larosa et al.

Current Opinion in Infectious Diseases • 2024

Purpose of review To discuss novel antibiotics under clinical development, focusing on agents showing in-vitro activity against metallo-β-lactamases (MBL)-producing carbapenem-resistant Gram-negative bacteria (CR-GNB). Recent findings Currently, only a few approved agents show activity, alone or in synergistic combinations, against MBL-producing CR-GNB. If approved by regulatory agencies in case of favorable results from ongoing (and, for some agents, already completed) phase-3 studies, some novel β-lactam/β-lactamase inhibitor (BL/BLI) combinations could become available in the next few years as additional important options for treating MBL-producing CR-GNB infections. Additional interesting agents that belong both to BL/BLI combinations and to antibiotic classes other than BL and BL/BLI combinations have also shown activity against MBL-producing CR-GNB, with most of them being in early phases of clinical development. Summary Improving the use of these novel agents through virtuous antimicrobial stewardship frameworks able to guarantee both the efficacious treatment of infections requiring their use and the avoidance of their use whenever not necessary remains a challenge of utmost importance that should not be overlooked.

, Nampon Arttaweeporn

• 2007

Biosurfactants are gaining more and more attention and have already been utilized for a number of important industrial applications due to their biodegradability, capability to be produced from renewable resources, good functionality under extreme conditions (particularly those pertaining tertiary crude-oil recovery), and good comatibity with human beings. From this research, a biosurfactant solution produced from Bacillus Subtilis PT4, isolated from an oil sludge, was studied for its properties. The surface tension of nutrient broth was reduced to 26.4 mN/m when PT4 was incubated with 2% palm oil at 37C, 51 hours, as compared to an incubation time of 36 hours with sludge oil, suggesting that PT4 is more compatible with sludge oil than with palm oil. The critical micelle concentration (CMC) of the produced biosurfactants, after cultivation for 51 hours, was found to be 25 mg/1, corresponding to a minimum surface tension of 26.4 mN/m. From the oil recovery results, the efficiency of the produced biosurfactants was 63.56% for motor oil and 59.10% for palm oil.

, Titarat Lertchaowayuth

• 2008

The inhibitory effect of Lactococcus lactis WNC20 (Ll. 20), a nisin producing lactic acid bacteria, on food-borne bacteria was investigated by testing in yoghurt as a food model, as compared to commercial starter, LC. Experimental groups comprised of control A (Ll. 20 as starter culture), control B (commercial starter culture, LC), control C (food-borne pathogen), treatment A (Ll. 20 and food-borne pathogen) and treatment B (LC and food-borne pathogen). Starter culture inoculum of ~6-7- log cycle was used for all experiments. After 48 hours, Staphylococcus aureus ATCC25923 was not detected in treatment A after addition either at 2- or 3- log cycle. While, addition of S. aureus at 4- log cycle, S. aureus decreased 2- log cycle after 24 hours of incubation. However, no detection of S. aureus was observed in treatment B after 48 hours. With regard to, Bacillus cereus ATCC1729, Listeria monocytogenes DMST17303, Escherichia coli ATCC25922 and Salmonella Typhimurium ATCC13311, at 2-, 3- or 4- log cycles, were added into milk at the same time as the starter culture. Lis. monocytogenes was not detected in both treatment A and B after 48 hours incubation. B. cereus was inhibited at 16 hours incubation and increased to 5- log cycle at 48 hours in treatment A when added B. cereus at 2- and 3- log cycles. While, addition B. cereus 4- log cycle, it was inhibited after 16 hours and increased to 5- log cycle after 24 hours in treatment A. B. cereus in treatment B was not detected after 8 hours of incubation, added B. cereus starting at 2-, 3- and 4- log cycles. No viable cell of E. coli (<10 CFU/mL) in treatment A was detected after 72 hours, but in treatment B E. coli was inhibited after 48 hours. With regard to, Sal. Typhimurium starting at 2- and 3- log cycles was not detected after 24 hours of incubation yoghurt, and after 72 hours for adding 4- log cycle in treatment A. Whereas, in treatment B Sal. Typhimurium was not detected after 16 and 24 hours for adding 2-, 3- and 4- log cycles, respectively. All experiments found that pH always decreased whereas percentage of total acid always increased throughout the experiment. Nisin Z was also found from yoghurt Ll. 20, which showed inhibition on, Lb. plantarum TISTR850 growth by agar diffusion technique. Therefore, Ll. 20 could be used as starter in Nham preparatAAion in order to reduce food-borne bacteria contamination.

Pradeep Kumar Singh Sandesh Chibber, Veerendra Singh Nagoria

International Journal of Current Microbiology and Applied Sciences • 2022

Biosurfactants having the characteristics of amphipathic compounds. Biosurfactants are produced by several microorganisms which include Acinetobacter spp., Bacillus spp., Candida antarctica, Pseudomonas aeruginosa. Different screening methods, for example oil spreading assay, blood agar hemolysis, emulsification assay, foaming activity are used to select biosurfactant producing microbes. The main objective of this research work was to isolate and characterize the biosurfactant producing bacteria from oil contaminated soil. By using kerosene oil as the sole carbon source, bacterial strain was isolated and screened having the characteristics of biosurfactant properties. Number of techniques like oil spreading technique, blood hemolysis test, foaming activity, and emulsification activity were performed for the screening of the biosurfactant producing bacteria, and found positive oil spreading technique in bacterial strain B1 and B2. Strain B1 (52%) has high emulsifying activity, whereas in B2 it was around 42 %. Strain B1 showed complete breakdown of the hemoglobin of the red blood cells in the vicinity of bacterial colony i.e. β blood hemolysis test and in B2 it is lack of hemolysis i.e. γ hemolysis. It was observed that foaming stability in B2 strain is lesser than B2. Both the isolated bacterial strains B1 and B2 showed Gram positive, and they are in rod and circular shape respectively. From the result of various biochemical characterization and cell morphological characterization, the isolated strain was bacillus type bacteria.

Nandini Prajapati, Hetvi Rami, Nimisha Patel

International Journal of Current Microbiology and Applied Sciences • 2023

Today, environment is polluted with waste which is not degradable. Waste placed at landfill dumping site which contain plastics account about 20% by volume of municipal solid wastes and reduce the capacity of precious landfill sites. Poly hydroxyl butyrate (PHB) which is a biodegradable and biocompatible thermoplastic compound has broadly similar physical properties to poly (propylene). It has many applications in medicine, veterinary practice, tissue engineering materials, food packaging and agriculture due to its biodegradability. In the present study, we focus on screening of bioplastics producing bacterial isolates from the soil sample from dumping site. The bacteria were characterized by their cultural characteristics, morphology and biochemical test. PHB producing bacterial isolate was further detected by using Sudan black- B staining reagent. Attempt was made to produce and extract PHB by using our bacterial isolate. Isolate exhibited significant PHB yields, thus showing a potential for further exploitation. Further analyses are currently ongoing to try to extract and characterize PHB granules.

Shivalingaiah S, Bindushree ­H.S, Basavaraju G.L et al.

Current Agriculture Research Journal • 2024

Soil is a vital ecosystem for various life forms, including bacteria. Bacteria are the main group of soil microbes, mostly because of their ability to produce various extracellular enzymes. Amylases are the enzymes that break down starch, which are essential in biotechnology industries such as food, fermentation, textiles, and paper manufacturing. The demand for amylase is often high since many enterprises do not have access to local supplies of the enzyme. The objective of the current investigation is to isolate and identify bacterial isolates that can produce the enzyme amylase from soil samples. Soil samples were collected from the unexplored Biligiriranga hills (11.9988° N, 77.1398° E) in south-western Karnataka Bacterial isolates were isolated from soil samples and were primarily screened on starch agar medium to determine the amylase production. Three out of fifteen bacterial isolates that produced amylase were selected based on the highest clear zone around the bacterial colony. These three bacterial isolates were identified both microscopically and biochemically. Gram staining demonstrated that the isolates are rod-shaped and gram-positive organisms. Biochemical studies indicated that the isolates were positive for the catalase and starch hydrolysis tests, whereas negative for the potassium hydroxide and methyl red tests. Besides, 16S rRNA gene amplification and sequencing confirmed the isolate as Bacillus subtilis. The 16S rRNA sequence of B. subtilis strain B has been deposited in the NCBI GenBank. The optimal growth conditions observed in B. Subtilis. The optimal growth conditions observed in B. Subtilis were 37° C temperature at pH 7 and incubation period for 37h. Thus, the isolation and identification of soil-derived amylase-producing bacteria are crucial for understanding their potential applications in various industrial processes, such as bioremediation, waste management, and the production of enzymes for food, pharmaceuticals, and biofuel industries.

Tadej ČEPELJNIK, Romana MARINŠEK-LOGAR

Acta agriculturae Slovenica • 2002

Bacteria belonging to or resembling the genus Butyrivibrio represent a significant proportion of bacterial isolates from different mammalian gastro-intestinal tracts from all over the world. The main characteristic of this genus is production of butyric acid, which has an important role in maintaining colonic health. The rumen strains – B. fibrisolvens are also known producers of conjugated linoleic acid (CLA), bacteriocins and several hydrolytic enzymes that contribute to effective forage digestion. Genus Butyrivibrio contains isolates that are very diverse in both genomic and phenotypic properties. Different researchers have proposed the grouping of isolates on the basis of some specific characteristics but up to now none was recognised as a new species. Therefore, a complex approach is needed to set basis for new species delineation and characterisations and to define a set of reasonable diagnostic methods for their discrimination.

, Joanna Fay

• 2013

Given the alternative functions of “antibiotics” as communication molecules or participants in metabolism, it seems probable that production might be influenced by factors such as nutrient availability, interactions with neighboring microbes, and/or colony or community structure and maturity. With this in mind, the present study aimed to broaden the scope of the search for novel antibiotics by experimenting with the following parameters: source of bacterial isolation, growth and assay media, and culturing techniques. Bacteria for this study were isolated from two categories of soil (petroleum-contaminated or uncontaminated) to compare diversity and antimicrobial activity. Compared to the uncontaminated soil, isolates of the petroleum-contaminated soil were as diverse and antimicrobial activity was as frequent. Antimicrobial assays were done on three different types of agar, including the standard Mueller-Hinton and two types of medium typically used for fungal growth, Yeast Peptone Dextrose (YPD) and Yeast Mold (YM). Compared to results on Mueller-Hinton, much more antimicrobial activity was seen when using YPD and YM. Finally, spent media assays were performed with pure and mixed cultures to determine if exposure to a target pathogen affects the production of antimicrobial substances by soil isolates. Those bacteria with activity against Pseudomonas aeruginosa in perpendicular streak tests were grown as mixed cultures with P. aeruginosa. In the case of Bacillus amyloliquefaciens and Pseudomonas marginalis, discs impregnated with concentrated spent media from these mixed cultures resulted in significant dose-dependent inhibition of P. aeruginosa. The same assay using pure cultures showed no inhibition.

, Patcharin Boon-eiam

• 2007

Screening of cellulase- and xylanase-producing bacteria from 40 and 45 soil samples, respectively and 10 biofertilizer samples, 51 bacterial strains were isolated (27 cellulase-producing and 24 xylanase producing strains). On the basis of their phenotypic and chemotaxonomic characteristics including phylogenetic analysis using 16S rRNA gene sequences, 7 strains were closed to Cohnella, 4 to Paenibacillus, 13 to Bacillus, 17 to Pseudomonas, 9 to Acinetobacter and 1 to Escherichia. The similarity of 16S rRNA gene sequence revealed that the cellulase-producing bacteria: PA4-1 (Group 1) was closely related to Cohnella thermotolerans CCUG 47242T (97.2%). PBS5 (Group 2), T3-3 (Group 3) and T3-2 (Group4) were closely related to Bacillus drentensis LMG 21831T (98.8%), B. megaterium IAM 13418T (88.0%) and B. cereus IAM 12605T (88.7%), respectively. N14-2 (Group 5) showed 93.0% similarity to Pseudomonas pseudoalcaligenes JCM 5968T. T6-4 (Group 6) showed 92.7% similarity to Pseudomonas nitroreducens DSM 14399T. The xylanase-producing bacteria: PT4-2 (Group 1) and PN12-3 (Group 3) showed 92.4 and 91.2% similarities to C. panacarvi KCTC 13060T, respectively. PN8-3 (Group 2) and PT6-2 (Group 4) showed 91.4 and 96.4% similarities to C. thermotolerans CCUG 47242T. PN13-1 (Group 5) and T3-2X (Group 6) showed 87.4 and 95.3% similarities to Paenibacillus agarexedens DSM 1327T. PT2-3 (Group 7) was closely related to Paenibacillus popilliae ATCC 14706T (91.8%). PN8-2 (Group 8) was closely related to B. subtilis KCTC 3135T (98.8%). PN1-2 (Group 9) was closely related to Pseudomonas aeruginosa MML 2212T (97.0%). PN9-3 (Group 10) showed 98.4% similarity to Acinetobacter baumannii ATCC 19606T. N9-2 (Group 11) was closely related to Escherichia coli KCTC 2441T (97.6%). Tested strains of Paenibacillus and Bacillus contained meso-diaminopimelic in cell wall peptidoglycan and had 7 isoprene units (MK-7) as predominant menaquinone. The DNA G+C contents of Cohnella strain were 52.3-64.9 mol%. In this study, Cohnella strain PA4-1, PT4-2, PN8-3, PN12-3 and PT6-2, Paenibacillus strain PN13-1, T3-2X and PT2-3, Bacillus strains PBS5 and T3-2, and Pseudomonas strain N14-2, T6-4 and PN1-2 were new species. However, DNA-DNA hybridization study were required to confirm their taxonomic position. Among 51 bacteria isolated, 27 cellulase-producing bacteria isolated produced cellulase 0-0.015 U/ml while the 24 xylanase-producing bacteria produced xylanase 0-0.48 U/ml. Strain PB11 produced highest endoglucanase. Optimal temperature and pH for endoglucanase activity were 60 °C, pH 7.5. Maximum endoglucanase activity was 0.11 U/ml, PA4-3 produced highest ß-glucosidase. Optimal temperature and pH for ß-glucosidase activity were 60 °C, pH 7.0. Maximum ß-glucosidase activity was 0.0091 U/ml. Optimal temperature and pH for xylanase activity were 65 °C, pH 8.0. Maximum xylanase activity was 0.51 U/ml.

Chunling Chang, Yue Guo, Kuanqiang Tang et al.

Microorganisms • 2024

The biological degradation of plant residues in the soil or on the soil surface is an integral part of the natural life cycle of annual plants and does not have adverse effects on the environment. Crop straw is characterized by a complex structure and exhibits stability and resistance to rapid microbial decomposition. In this study, we conducted a microcosm experiment to investigate the dynamic succession of the soil microbial community and the functional characteristics associated with lignocellulose-degrading pathways. Additionally, we aimed to identify lignocellulose-degrading microorganisms from the straw of three crop species prevalent in Northeast China: soybean (Glycine max Merr.), rice (Oryza sativa L.), and maize (Zea mays L.). Our findings revealed that both the type of straw and the degradation time influenced the bacterial and fungal community structure and composition. Metagenome sequencing results demonstrated that during degradation, different straw types assembled carbohydrate-active enzymes (CAZymes) and KEGG pathways in distinct manners, contributing to lignocellulose and hemicellulose degradation. Furthermore, isolation of lignocellulose-degrading microbes yielded 59 bacterial and 14 fungal strains contributing to straw degradation, with fungi generally exhibiting superior lignocellulose-degrading enzyme production compared to bacteria. Experiments were conducted to assess the potential synergistic effects of synthetic microbial communities (SynComs) comprising both fungi and bacteria. These SynComs resulted in a straw weight loss of 42% at 15 days post-inoculation, representing a 22% increase compared to conditions without any SynComs. In summary, our study provides novel ecological insights into crop straw degradation by microbes.

Karl J. Romanowicz, Z. Freedman, R. Upchurch et al.

FEMS Microbiology Ecology • 2016

Predicting the impact of environmental change on soil microbial functions requires an understanding of how environmental factors shape microbial composition. Here, we investigated the influence of environmental factors on bacterial and fungal communities across an expanse of northern hardwood forest in Michigan, USA, which spans a 500-km regional climate gradient. We quantified soil microbial community composition using high-throughput DNA sequencing on coextracted rDNA (i.e. total community) and rRNA (i.e. active community). Within both bacteria and fungi, total and active communities were compositionally distinct from one another across the regional gradient (bacteria P = 0.01; fungi P < 0.01). Taxonomically, the active community was a subset of the total community. Compositional differences between total and active communities reflected changes in the relative abundance of dominant taxa. The composition of both the total and active microbial communities varied by site across the gradient (P < 0.01) and was shaped by differences in soil moisture, pH, SOM carboxyl content, as well as C and N concentration. Our study highlights the importance of distinguishing between metabolically active microorganisms and the total community, and emphasizes that the same environmental factors shape the total and active communities of bacteria and fungi in this ecosystem.

P. Amato, M. Joly, L. Besaury et al.

PLOS ONE • 2017

Clouds are key components in Earth’s functioning. In addition of acting as obstacles to light radiations and chemical reactors, they are possible atmospheric oases for airborne microorganisms, providing water, nutrients and paths to the ground. Microbial activity was previously detected in clouds, but the microbial community that is active in situ remains unknown. Here, microbial communities in cloud water collected at puy de Dôme Mountain’s meteorological station (1465 m altitude, France) were fixed upon sampling and examined by high-throughput sequencing from DNA and RNA extracts, so as to identify active species among community members. Communities consisted of ~103−104 bacteria and archaea mL-1 and ~102−103 eukaryote cells mL-1. They appeared extremely rich, with more than 28 000 distinct species detected in bacteria and 2 600 in eukaryotes. Proteobacteria and Bacteroidetes largely dominated in bacteria, while eukaryotes were essentially distributed among Fungi, Stramenopiles and Alveolata. Within these complex communities, the active members of cloud microbiota were identified as Alpha- (Sphingomonadales, Rhodospirillales and Rhizobiales), Beta- (Burkholderiales) and Gamma-Proteobacteria (Pseudomonadales). These groups of bacteria usually classified as epiphytic are probably the best candidates for interfering with abiotic chemical processes in clouds, and the most prone to successful aerial dispersion.

J. Bradley, Christopher B. Trivedi, M. Winkel et al.

Geobiology • 2022

Glacier and ice sheet surfaces host diverse communities of microorganisms whose activity (or inactivity) influences biogeochemical cycles and ice melting. Supraglacial microbes endure various environmental extremes including resource scarcity, frequent temperature fluctuations above and below the freezing point of water, and high UV irradiance during summer followed by months of total darkness during winter. One strategy that enables microbial life to persist through environmental extremes is dormancy, which despite being prevalent among microbial communities in natural settings, has not been directly measured and quantified in glacier surface ecosystems. Here, we use a combination of metabarcoding and metatranscriptomic analyses, as well as cell‐specific activity (BONCAT) incubations to assess the diversity and activity of microbial communities from glacial surfaces in Iceland and Greenland. We also present a new ecological model for glacier microorganisms and simulate physiological state‐changes in the glacial microbial community under idealized (i) freezing, (ii) thawing, and (iii) freeze–thaw conditions. We show that a high proportion (>50%) of bacterial cells are translationally active in‐situ on snow and ice surfaces, with Actinomycetota, Pseudomonadota, and Planctomycetota dominating the total and active community compositions, and that glacier microorganisms, even when frozen, could resume translational activity within 24 h after thawing. Our data suggest that glacial microorganisms respond rapidly to dynamic and changing conditions typical of their natural environment. We deduce that the biology and biogeochemistry of glacier surfaces are shaped by processes occurring over short (i.e., daily) timescales, and thus are susceptible to change following the expected alterations to the melt‐regime of glaciers driven by climate change. A better understanding of the activity of microorganisms on glacier surfaces is critical in addressing the growing concern of climate change in Polar regions, as well as for their use as analogues to life in potentially habitable icy worlds.

Yijin Yang, Wuyao Hu, Yongjun Xia et al.

Frontiers in Microbiology • 2020

Huangjiu (Chinese rice wine) has been consumed for centuries in Asian countries and is known for its unique flavor and subtle taste. The flavor compounds of Huangjiu are derived from a wide range of sources, such as raw materials, microbial metabolic activities during fermentation, and chemical reactions that occur during aging. Of these sources, microorganisms have the greatest effect on the flavor quality of Huangjiu. To enrich the microbial diversity, Huangjiu is generally fermented under an open environment, as this increases the complexity of its microbial community and flavor compounds. Thus, understanding the formation of flavor compounds in Huangjiu will be beneficial for producing a superior flavored product. In this paper, a critical review of aspects that may affect the formation of Huangjiu flavor compounds is presented. The selection of appropriate raw materials and the improvement of fermentation technologies to promote the flavor quality of Huangjiu are discussed. In addition, the effects of microbial community composition, metabolic function of predominant microorganisms, and dynamics of microbial community on the flavor quality of Huangjiu are examined. This review thus provides a theoretical basis for manipulating the fermentation process by using selected microorganisms to improve the overall flavor quality of Huangjiu.

Tingting Deng, Linmin Wang, Tianhui Zhu

Microorganisms • 2025

Chestnut blight, caused by Cryphonectria parasitica (Murrill) M.E. Bar, is a destructive fungal disease threatening chestnut cultivation and production. In response to the limitations of chemical control, biological control using antagonistic microbes has gained increasing attention. A rhizosphere-derived bacterium, strain D39, was isolated from healthy chestnut trees and identified as Bacillus amyloliquefaciens based on morphological characteristics and the phylogenetic analysis of 16S rRNA and gyrA genes. The antifungal activity of strain D39 against C. parasitica was evaluated using dual-culture and double-layer Oxford cup assays. The strain exhibited broad-spectrum and stable antagonistic effects and harbored five key genes associated with antimicrobial compound biosynthesis (srfAA, ituC, fenD, bmyB, and bacA), as confirmed by PCR. A 145 kDa extracellular protein with strong antifungal activity was extracted and purified by ammonium sulfate precipitation, DEAE ion-exchange chromatography, and Sephadex G-75 gel filtration. LC-MS analysis identified the protein as a serine peptidase belonging to the S8 family, and its structure was predicted using multiple bioinformatic tools. In pot experiments, treatment with the strain D39 significantly reduced disease severity, achieving control efficiencies of 66.07% and 70.89% at 10 and 20 days post-inoculation, respectively. These results demonstrate that B. amyloliquefaciens D39 has strong potential as a biocontrol agent against chestnut blight, offering an effective and environmentally friendly alternative for disease management.

Zhibin Guan, Serxho Selmani, Eric Schwartz et al.

ChemRxiv • 2021

Fuel-driven dissipative supramolecular assemblies in biology, such as actin filaments and microtubules contribute to the formation of complex, dynamic structures in living organisms and give rise to emergent functions such as motility, homeostasis, self-healing, and camouflage. Several synthetic dissipative supramolecular materials have been created using chemicals or light as fuel, with the goal of furthering our understanding of biological systems and creating synthetic materials that have life-like dynamic properties. However, electrical energy, one of the most common energy sources, has remained mostly unexplored for such purposes. Here we demonstrate the use of electrically fueled dissipative assembly as a new platform for creating active supramolecular materials. Through an electrochemical redox reaction network operating in mild aqueous buffers, a transient and highly active supramolecular assembly based on a redox-sensitive cysteine derivative is achieved by applying an electric potential. The dissipative self-assembly as well as its emergent properties can be spatiotemporally controlled by modulation of electrical signals on patterned microelectrodes. Using electrical energy as a readily available and clean fuel, we are able to create dissipative supramolecular materials rapidly (in seconds to minutes) and repetitively under mild conditions with directional and spatiotemporal control. As electronic signals are the default information carriers in modern technology, the described approach offers a promising opportunity to integrate active materials into electronic devices for bioelectronics applications.

Taoran Yang, Yinghui He, Ming Yang et al.

Microorganisms • 2024

The deep ocean harbors a group of highly diversified microbes, while our understanding of the active microbes that are real contributors to the nutrient cycle remains limited. In this study, we report eukaryotic and prokaryotic communities in ~590 m and 1130 m depths using 16S and 18S rRNA Illumina reads (miTags) extracted from 15 metagenomes (MG) and 14 metatranscriptomes (MT). The metagenomic 16S miTags revealed the dominance of Gammaproteobacteria, Alphaproteobacteria, and Nitrososphaeria, while the metatranscriptomic 16S miTags were highly occupied by Gammaproteobacteria, Acidimicrobiia, and SAR324. The consistency of the active taxa between the two depths suggests the homogeneity of the functional microbial groups across the two depths. The eukaryotic microbial communities revealed by the 18S miTags of the metagenomic data are dominated by Polycystinea; however, they were almost all absent in the 18S metatranscriptomic miTags. The active eukaryotes were represented by the Arthropoda class (at 590 m depth), Dinophyceae, and Ciliophora classes. Consistent eukaryotic communities were also exhibited by the 18S miTags of the metatranscriptomic data of the two depths. In terms of biodiversity, the ACE and Shannon indices of the 590 m depth calculated using the 18S metatranscriptomic miTags were much higher than those of the 1130 m depth, while a reverse trend was shown for the indices based on the metagenomic data. Our study reports the active microbiomes functioning in the nutrient utilization and carbon cycle in the deep-sea zone, casting light on the quantification of the ecological processes occurring in the deep ocean.

Matthieu Nicault, Ali Zaiter, Stéphane Dumarcay et al.

Microorganisms • 2021

The bacteria of the genus Streptomyces and Basidiomycete fungi harbor many biosynthetic gene clusters (BGCs) that are at the origin of many bioactive molecules with medical or industrial interests. Nevertheless, most BGCs do not express in standard lab growth conditions, preventing the full metabolic potential of these organisms from being exploited. Because it generates biotic cues encountered during natural growth conditions, co-culture is a means to elicit such cryptic compounds. In this study, we explored 72 different Streptomyces-fungus interaction zones (SFIZs) generated during the co-culture of eight Streptomyces and nine fungi. Two SFIZs were selected because they showed an elicitation of anti-bacterial activity compared to mono-cultures. The study of these SFIZs showed that co-culture had a strong impact on the metabolic expression of each partner and enabled the expression of specific compounds. These results show that mimicking the biotic interactions present in this ecological niche is a promising avenue of research to explore the metabolic capacities of Streptomyces and fungi.

Sidorov Yu.G., Sidorov G. Yu., Varavin V.S.

Semiconductors • 2023

Influence of water solutions with various pH and electrochemical treatment in cathode position on concentration of charge carriers in samples Cd x Hg 1-x Te with x=0.2-0.3 is investigated. Cathodic treatment cadmium-mercury-tellurium at small density current increases concentration of donors, and at high density acceptors are formed. It is supposed that hydroxyl groups create acceptors centers, introduce in interstitial cadmium-mercury-tellurium. At treatment for a long time (it is more than 20 h) or acceptors are formed with concentration at level of 10 16 cm -3 (at high activity of hydrogen), or donors with concentration of 10 14 cm -3 (at low activity of hydrogen) are uniform distribution on all thickness of cadmium-mercurytellurium film and does not vary with the subsequent increase in time of treatment. Keywords: CdHgTe, electrochemical treatment, acceptors, activity of hydrogen.

Tecla Ciociola, Laura Giovati, Stefania Conti et al.

Microorganisms • 2021

Mycoses still represent relevant opportunistic infections worldwide, although overshadowed in recent years by other severe and more widespread infections. Moreover, deep-seated mycoses are often accompanied by unacceptably high mortality rates. Etiologic agents include endogenous components of the mycobiota, Candida and Malassezia species above all, and exogenous species, both yeasts and filamentous fungi. Old and new fungal pathogens are increasingly characterized by resistance to the existing antifungal agents, making imperative the search for effective and safe new therapeutics. Among the candidate molecules proposed in recent decades, synthetic peptides derived from the complementarity determining and constant regions of diverse antibodies (Abs), as well as the translated products of Ab-encoding genes, have proved of considerable interest. Their anti-infective activities, regardless of the specificity and isotype of the originating Ab, will be briefly presented and discussed in the light of their different mechanisms of action. Intriguing suggestions on the possible function of Abs after their half-life will be presented, following the recent detection, in human serum, of an antimicrobial Ab-derived peptide. Overall, Abs could represent a source of biologically active, highly flexible peptides, devoid of detectable toxicity, which can be easily synthesized and manipulated to be used, alone or in association with already available drugs, for new anti-infective strategies.

Toshiyuki Ohashi, Hironori Kobayashi

Batteries &amp; Supercaps • 2025

A simple electrolyte/electrode interface using a thin film of active material in cathode is constructed to enable measurement of electrochemically active surface area (ECSA) in all‐solid‐state batteries. The correlation between specific capacitance and specific surface area at the interface is investigated. The correlation has a linear relationship and give a calibration curve. Using the calibration curve as a clue, ECSA of a composite electrode is quantitatively determined from the specific capacitance of the composite cell obtained using electrochemical impedance spectroscopy.

Kyle Diederichsen, Yayuan Liu, T. Alan Hatton

ECS Meeting Abstracts • 2022

Within the field of carbon capture, electrochemically driven methods have drawn increasing attention due to their ability to operate at ambient temperature, their efficient scaling, and potentially low energetic cost. An important consideration in such systems is the method of gas contacting to enable efficient CO 2 separation from the feed gas. Previous flow-based electrochemical processes that enable large-area gas contacting and desorption of concentrated CO 2 at a point location all utilize water as the solvent and can require significant water feeds due to high evaporation rates. Here, we demonstrate the use of liquid, redox-active sorbents in a flow system that can decouple the electrode size from gas contacting area. The concept sorbent is a nonvolatile, liquid quinone species that can be reversibly reduced and oxidized to capture and release CO 2 , respectively. In this initial study, we employ the liquid quinone with sodium salts to achieve sorbent capacities near 2.5M CO 2 and couple this sorbent to a ferrocene-derived counter electrolyte in a continuous capture – release process. Through this, we illustrate considerations in the salt choice, counter-electrolyte, and system design to best enable this concept sorbent, and discuss many opportunities for future optimizations.

Erhan Atci, Timothy Ewing, Haluk Beyenal

ECS Meeting Abstracts • 2016

Recently, some bacterial biofilms have been shown to colonize and transfer their extracellular electrons to solid electrodes in microbial fuel cells and in bioelectrochemical systems [1, 2]. This class of microorganisms is described as electrochemically active biofilms (EABs) that are able to transfer electrons outside the cell to insoluble electron acceptors (iron or metal oxides) or to solid electrodes via extracellular electron transfer [3, 4]. The need to understand the distribution of proteins involved in electron transfer in EABs is of critical importance. These proteins can be identified using mass spectroscopy (MS). It is known that there is a wide spectrum of applications in which mass spectroscopy (MS) can provide information from a sample of EABs, and these applications can easily translate to all areas of research in EABs. However, the spatial diversity of microbial functions within EABs cannot be resolved because all of the current MS analysis techniques are conducted in the bulk liquid, which provides no spatial resolution with respect to the structure of EABs. Separation techniques can be combined with MS to present a more focused data set with regard to composition; however, MS analysis still lacks the capacity to investigate variation with depth of EABs. Depth profiles will have the potential to elucidate the mechanisms of the surrounding matrix and the roles of the microorganism with respect to the layers of EABs and the growth interface. To date, this MS technique has not been used for depth profiling in EABs. This is mostly because there was no tool available to extract samples from different depths in EABs. Microcapillaries with a several-micrometer tip diameter can be used in EABs without damaging its structure for the depth profiling of selected chemicals. The goal of this work was to develop a microcapillary system which can extract samples at desired depth inside the EABs. Ambient pressure surface ionization mass spectrometry is used to obtain a chemical analyte for sampling from interfaces without special sample preparation [5]. Desorption electrospray ionization (DESI) is an ambient ionization technique in which charged droplets from an electrosonic spray ionization source are aimed towards a surface with a proximal atmospheric pressure mass spectrometer inlet. In this technique, analyte molecules are collected from flat surfaces followed by ionization using a self-aspirating nanoelectrospray. This technique directly transports and ionizes an analyte that is desorbed from a surface into a liquid and it is called as nanospray DESI (nano-DESI). The nanospray capillary transports the charged liquid to the mass spectrometer inlet directly, eliminating splashing while minimizing analyte transport distance. The target application of the developed microcapillary system is to interface it with a nano-DESI sensor which can be used to characterize in situ , depth-resolved analyses of metabolites and possibly proteins. The developed nano-DESI sensor is composed of two microcapillaries placed in an outer case made of glass. Figure 1 shows an image of a developed nano-DESI sensor. In this system, the solvent delivery and its collection were made from the same microcapillaries. We managed to operate the sensor between 10 nL/min and 100 mL/min flow rates. After optimization of the flow rates, we tested it in EABs. EABs were grown according to our previously published paper and book [6, 7]. While we had succeeded in developing a nano-DESI sensor, we found unexpected challenges using it with EABs. Finally, the microcapillary system developed for this work enabled us to use it for quantifying electron transfer processes in EABs [7]. References: 1. Hamelers, H.M., et al., New applications and performance of bioelectrochemical systems. Applied Microbiology and Biotechnology, 2010. 85 (6): p. 1673-1685. 2. Logan, B.E., Exoelectrogenic bacteria that power microbial fuel cells. Nat Rev Micro, 2009. 7 (5): p. 375-381. 3. Lovley, D.R., Microbial fuel cells: novel microbial physiologies and engineering approaches. Current Opinion in Biotechnology, 2006. 17 (3): p. 327-332. 4. Logan, B.E., et al., Microbial Fuel Cells: Methodology and Technology†. Environmental Science &amp; Technology, 2006. 40 (17): p. 5181-5192. 5. Roach, P.J., J. Laskin, and A. Laskin, Nanospray desorption electrospray ionization: an ambient method for liquid-extraction surface sampling in mass spectrometry. Analyst, 2010. 135 (9): p. 2233-2236. 6. Lewandowski, Z. and H. Beyenal, Fundamentals of Biofilm Research, Second Edition . 2014: Taylor &amp; Francis. 7. Babauta, J.T. and H. Beyenal, Local Current Variation by Depth in Geobacter Sulfurreducens Biofilms. Journal of The Electrochemical Society, 2014. 161 (13): p. H3070-H3075. Figure 1

Ariel Friedman, Lior Elbaz

ECS Meeting Abstracts • 2024

The development of platinum group metal-free catalysts is considered the most prominent path for reducing the cost of low-temperature fuel cells (LTFC). Despite the great advancement in the field, its further progress is currently limited by the ability to understand and mitigate the catalysts’ degradation mechanisms, which up to recent years was limited by the lack of activity descriptors. Recent work showed that this could be solved using Fourier-transformed alternating current voltammetry that enables to deconvolute Faradaic currents arising from the redox reaction of the active sites from the capacitive currents, and by that accurately measure the electrochemically active site density of these catalysts in situ fuel cells. However, the analysis of the results can be complex, requiring simulation software for accurate parameter extraction. Herein, a simplified analysis of Fourier-transformed alternating current voltammetry is presented. This was done by mapping the influence of various variables, such as resistivity, capacitance, and thermodynamic and kinetic dispersion, on the accuracy of electrochemically active site density measurements. Under specific, yet realistic, operating conditions, a single equation with the peak current of the 5th harmonic as the only variable can be used to quantify electrochemically active site density with high accuracy. This approach was demonstrated using molecular catalysts, iron phthalocyanine, as a model molecule, and a commercial, heat-treated catalyst.

Pavithra Bhakthi Jayathilaka, Athula Bandara, Nadeeshani Nanayakkara et al.

Research Square • 2023

Abstract Anode material plays big role in electrochemical oxidation process of water treatment. Since its coating composition can affect the degradation path way, the reaction mechanism and the efficiency of electrochemical oxidation process, it is important to identify the optimum conditions of a given material composition of a high electrochemical active area. In this work, central composite design with response surface method was implemented to optimize Ir and Sb contents of Ti/IrO 2 -Sb 2 O 3 anode. In order to do that, response factors (i.e. anodic charge and open circuit potential value), which are related to electrochemically active area of the anode were monitored. They were expressed in second-order functions of two factors such as Ir and Sb concentrations. Since these factors showed significant impact on anodic charge and open circuit potential values of the anode, statistical analysis was done in order to gain the understanding of them. ANOVA table results, R 2 and R adj values, lack of fit test and p values indicated that the models represent experimental data well. 3-D response surface and 2-D contour plots visualized the effects. Overall analysis of results found that 0.3625 mC anodic charge value and -0.0869 mV open circuit value can be obtained by optimum material conditions of 0.08 g/L and 0.92 g/L Ir and Sb concentrations respectively.

G-S Park, HS Kim, SG Doo

Microscopy and Microanalysis • 2006

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005

Soyoung Joo, Heon-Cheol Shin

ECS Meeting Abstracts • 2024

All-solid-state batteries (ASSBs) are currently receiving much attention as one of the most promising next-generation rechargeable battery systems due to their promise of high energy density and high safety. Despite many efforts to commercialize ASSBs, however, there are still many unresolved technical challenges. Unlike conventional lithium-ion batteries (LIBs), the interface between the cathode and electrolyte in ASSBs exhibits a complex degradation pattern that combines chemical and mechanical degradations. In particular, the high Ni content cathode materials in ASSBs are commonly known to suffer from significant additional degradation mechanism, e.g., volume expansion/contraction due to H2-H3 phase transitions at high voltages, resulting in particle cracking. This degradation of the integrity of the active material leads to a reduction in electrochemically active surface area (active area afterward) due to loss of contact between the active material and solid electrolyte, slow diffusion rate of lithium in the active material, and isolation of the active material. These issues are recognized as major contributors to cell performance degradation. Among these issues, the changes in the active area have a decisive impact on the rate of redox reactions that are key to battery charging and discharging kinetics, so accurate determination of the active area is crucial for the diagnosis and improvement of batteries. In the electrochemical analysis of ASSBs, the poor contact between the solid electrolyte and the active material, or the change of the contact properties during the battery operation, should be a very important consideration. Especially when determining kinetic factors such as charge transfer resistance and chemical diffusion coefficient of cathode material by electrochemical methods, the models we usually use include the electrode surface area value as an important variable, so the accurate estimation of the active area is indispensable for obtaining reliable electrochemical properties. Unlike typical LIBs, in ASSBs the active material/electrolyte interface contact properties change relatively significantly during repeated cycling, so devising a reliable technique to analyze the active area of active materials in ASSBs is very crucial for the research and development of ASSBs. However, to the best of our knowledge, there are still very few studies on this. In this study, we propose promising methods to measure the contact characteristics between the cathode material and the solid electrolyte in ASSBs, namely the electrochemically active surface area, and discuss their reliability based on intercomparison and literature reports. For this purpose, first, the method for determining the active area of active materials based on galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) reported in conventional LIBs was reviewed. Then, its applicability to ASSBs was explored, and a way to improve the reliability of the analysis was proposed. Specifically, a three-electrode cathode half-cell experiment was conducted to analyze the active area of the Ni-rich cathode. The active area was calculated by comparing the diffusion coefficient measured by EIS with that obtained by GITT. When comparing the active area determined at different voltages, it was observed that the active area varies significantly with voltage most likely due to the volume change caused by the H2-H3 phase transition. The second electrochemical method performed for the determination of the active area of the active material is based on the quantification of the lithium intercalation sites on the cathode surface based on the analysis of the frequency factor in Arrhenius expression. For this purpose, battery at different charge states were kept at high temperatures for long periods of time to induce interfacial degradation. The temperature-dependent charge transfer resistance was then determined by EIS analysis, which was used to interpret the redox (or lithium absorption/desorption) reactions kinetically. The experimental results showed that the redox reaction rate followed exactly the Arrhenius relationship for all the charge states used, but the activation energies and frequency factors changed differently depending on the charge state. In this study, we discuss these results in relation to various phenomena that may occur during high-temperature aging, such as the formation of rock salt structures and cracks on the nickel-rich cathode surface, and try to estimate the change in active area. In this study, the electrochemical analysis methods of the contact characteristics between the cathode and the solid electrolyte in ASSBs will be examined in depth and their reliability will be assessed. In addition, further improvements in active area analysis techniques for active materials in ASSBs will be discussed.

Yamini Jangir, Sarah French, Lily M. Momper et al.

bioRxiv (Cold Spring Harbor Laboratory) • 2016

Abstract Continental subsurface environments can present significant energetic challenges to the resident microorganisms. While these environments are geologically diverse, potentially allowing energy harvesting by microorganisms that catalyze redox reactions, many of the abundant electron donors and acceptors are insoluble and therefore not directly bioavailable. Extracellular electron transfer (EET) is a metabolic strategy that microorganisms can deploy to meet the challenges of interacting with redox-active surfaces. Though mechanistically characterized in a few metal-reducing bacteria, the role, extent, and diversity of EET in subsurface ecosystems remains unclear. Since this process can be mimicked on electrode surfaces, it opens the door to electrochemical techniques to enrich for and quantify the activities of environmental microorganisms in situ . Here, we report the electrochemical enrichment of microorganisms from a deep fractured-rock aquifer in Death Valley, California, USA. In experiments performed in mesocosms containing a synthetic medium based on aquifer chemistry, four working electrodes were poised at different redox potentials (272, 373, 472, 572 mV vs. SHE) to serve as electron acceptors, resulting in anodic currents coupled to the oxidation of acetate during enrichment. The anodes were dominated by Betaproteobacteria from the families Comamonadaceae and Rhodocyclaceae. A representative of each dominant family was subsequently isolated from electrode-associated biomass. The EET abilities of the isolated Delftia strain (designated WE1–13) and Azonexus strain (designated WE2–4) were confirmed in electrochemical reactors using working electrodes poised at 522 mV vs. SHE. The rise in anodic current upon inoculation was correlated with a modest increase in total protein content. Both genera have been previously observed in mixed communities of microbial fuel cell enrichments, but this is the first direct measurement of their electrochemical activity. While alternate metabolisms (e.g. nitrate reduction) by these organisms were previously known, our observations suggest that additional ‘hidden’ interactions with external electron acceptors are also possible. Electrochemical approaches are well positioned to dissect such extracellular interactions that may be prevalent in the subsurface.

Viktor Čolić

• 2024

Additively manufactured (AM) nickel electrodes offer a great potential as an efficient solution for oxygen evolution catalysts in alkaline electrolyzers, since advanced fabrication methods allow the design of high surface area electrodes. The accurate determination of the electrochemical active surface area (ECSA) is a key step in the evaluation of the intrinsic catalytic activity of complex electrodes. In this work, we fabricated Ni electrodes with different macroscopic lattice structures using laser powder bed fusion of metals (PBF-LB/M). The selected designs allow exploring the effects of the electrode geometry on the electrochemical performance. X-ray photon spectroscopy (XPS) and a non-contact optical profilometer (NCOP) were used to investigate the composition and surface morphology of the electrodes. The ECSA was determined by three different approaches. 1. Linear and non-linear allometric fitting of the double layer capacitance from voltammetric experiments. 2. Integration of the Ni2+/Ni3+ transition, also from voltammetry. 3. Assessing double layer capacitance determined from electrochemical impedance spectroscopy (EIS) at open circuit potential (OCP) and the adsorption capacitance for the oxygen evolution reaction (OER) intermediates. Comparing these methods, large deviations in the resulting ECSAs were found, motivating a comprehensive discussion. In addition, four different reactions were investigated, ferri-ferrocyanide redox system, hydrogen evolution, ethanol electrooxidation, and oxygen evolution reaction. The obtained results demonstrate the potential of AM to tailor electrode performance by altering electrode geometry. The findings underline the importance of the ECSA determination for the comparison of the electrocatalytic activity in different electrodes.

Shokaku Kim, Kouhei Shimada, Yohei Okada et al.

ECS Meeting Abstracts • 2014

Crosslinking reaction is a valuable method for the integration of two or more functionalities or properties to facilitate the effective design and fabrication of bioconjugates and nanomaterials. In particular, crosslinking reactions using photoactive linkers or click-chemistry for fluorescent labeling offer versatile strategies to manufacture biomolecular probes, which allow surface modification through stable covalent bonds. Although electroorganic synthetic methods have produced a wide variety of useful intermediate species under mild conditions, their application to practical crosslinking is restricted due to the difficulty of mass transfer, i.e., the unstable reactive intermediate generated from the electrode must be transported to another location. To date, attempts in solid-phase electroorganic synthesis have been limited mostly to immobilization of substrates on an electrode or indirect electroorganic synthesis. Furthermore, solid-phase syntheses often require excess amounts of reagents to complete target reactions due to low reactivity, and typical electroorganic approaches therefore suffer from in situ generation of unstable intermediates trapped within the solid-supports. Therefore, the development of electrochemically active crosslinkers for the modification of insoluble targets, nonconductive samples, and biomolecules remains a significant challenge. We have recently accomplished intermolecular carbon-carbon bond formation reactions with aliphatic alkenes via anodically generated cation intermediates to afford a variety of polycyclic systems. Furthermore, less reactive alkenes could be coupled with electrochemically activated substrates, which can be trapped in a thermomorphic solution-phase, spatially separated from the electrode, by using cyclohexane-nitromethane as a medium. These solution-phase reaction systems effectively accelerated intermolecular interactions between the less reactive olefins and unstable cation intermediates. We hypothesized that this approach would allow selective, direct and stable modification of alkene-attached insoluble targets with electrochemically active species. The electrochemically active crosslinking system could also enable the construction of a fluorescent probe, triggered by the formation of a covalent linkage. This strategy addresses the time-consuming, multistep post-processing problems associated with fluorescent labeling, such as washing and purification, and reduces false signals arising from nonspecific adsorption of a fluorophore or its undesired cleavage in the detection environment. To study the selectivity of the functional groups in this reaction system, electrochemical coupling reactions were conducted using phenol 1 in the presence of terminal mono-substituted olefins and trialkyl-substituted olefin 2 (Table1). These results indicate that the phenoxonium cations anodically generated in the LiClO 4 -MeNO 2 reaction system can be selectively trapped with trialkyl-substituted olefins to afford the cycloadduct as a fluorescent unit in high yields. Based on these results, we also attempted to synthesize a fluorescent probe composed of 2,7-dimethyl-6-octenoic acidon amino-modified silica and unactivated alkenes to confirm the lifetime of the phenoxonium cation. The size of the amino-silica particles was ca. 0.6-0.7 μm and the amino group content was 0.4 mmol/g. After the reaction, the mixture was washed in water and collected by filtration. Fluorescence on the silica was observed by fluorescent microscopy. The reactive site of the alkenes cannot approach the electrode because the silica molecule is too large, and thus, it was assumed that the phenoxonium cation was stable until reacting on the silica surface. In conclusion, an electrochemically active crosslinking reaction was developed to attach fluorescent probes to aliphatic alkenes. Several dihydrobenzofuran derivatives formed via [3+2] cyclization reactions exhibited fluorescence properties. Furthermore, this approach allows the effective and stable modification of alkene-attached silica gel as an insoluble target with electrochemically active species, which enables the construction of fluorescent probes, triggered by the formation of a covalent linkage. References Shokaku Kim, Kumi Hirose, Jumpei Uematsu, Yuzuru Mikami, Kazuhiro Chiba, Chem. Eur. J. , 2012 , 18(20) , 6284-6288.