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3 Biotech Dec 2016The continuous discharge of cyanide-containing effluents to the environment has necessitated for the development of environmentally benign treatment processes that would...
The continuous discharge of cyanide-containing effluents to the environment has necessitated for the development of environmentally benign treatment processes that would result in complete detoxification of the cyanide-containing wastewaters, without producing additional environmental toxicants. Since biological detoxification of hazardous chemical compounds has been renowned for its robustness and environmental-friendliness, the ability of the Exiguobacterium acetylicum (GenBank accession number KT282229) and Bacillus marisflavi (GenBank accession number KR016603) to co-metabolise thiocyanate (SCN) and free cyanide (CN) under alkaline conditions was evaluated. E. acetylicum had an SCN degradation efficiency of 99.9 % from an initial SCN concentration of 150 mg SCN/L, but the organism was unable to degrade CN. Consequently, B. marisflavi had a CN degradation efficiency of 99 % from an initial concentration of 200 mg CN/L. Similarly, the organism was unable to degrade SCN; hence, this resulted in the evaluation of co-metabolism of SCN and CN by the two microbial species. Optimisation of operational conditions was evaluated using response surface methodology (RSM). A numeric optimisation technique was used to evaluate the optimisation of the input variables i.e. pH, temperature, SCN and CN concentrations. The optimum conditions were found to be as follows: pH 9.0, temperature 34 °C, 140 mg SCN/L and 205 mg CN/L under which complete SCN and CN degradation would be achieved over a 168-h period. Using the optimised data, co-metabolism of SCN and CN by both E. acetylicum and B. marisflavi was evaluated, achieving a combined degradation efficiency of ≥99.9 %. The high degradative capacity of these organisms has resulted in their supplementation on an active continuous biological degradation system that is treating both SCN and CN.
PubMed: 28330245
DOI: 10.1007/s13205-016-0491-x -
BMC Biotechnology May 2020The bacterial genus Exiguobacterium includes several species that inhabit environments with a wide range of temperature, salinity, and pH. This is why the microorganisms...
BACKGROUND
The bacterial genus Exiguobacterium includes several species that inhabit environments with a wide range of temperature, salinity, and pH. This is why the microorganisms from this genus are known generically as polyextremophiles. Several environmental isolates have been explored and characterized for enzyme production as well as for bioremediation purposes. In this line, toxic metal(loid) reduction by these microorganisms represents an approach to decontaminate soluble metal ions via their transformation into less toxic, insoluble derivatives. Microbial-mediated metal(loid) reduction frequently results in the synthesis of nanoscale structures-nanostructures (NS) -. Thus, microorganisms could be used as an ecofriendly way to get NS.
RESULTS
We analyzed the tolerance of Exiguobacterium acetylicum MF03, E. aurantiacum MF06, and E. profundum MF08 to Silver (I), gold (III), and tellurium (IV) compounds. Specifically, we explored the ability of cell-free extracts from these bacteria to reduce these toxicants and synthesize NS in vitro, both in the presence or absence of oxygen. All isolates exhibited higher tolerance to these toxicants in anaerobiosis. While in the absence of oxygen they showed high tellurite- and silver-reducing activity at pH 9.0, whereas AuCl which was reduced at pH 7.0 in both conditions. Given these results, cell-free extracts were used to synthesize NS containing silver, gold or tellurium, characterizing their size, morphology and chemical composition. Silver and tellurium NS exhibited smaller size under anaerobiosis and their morphology was circular (silver NS), starred (tellurium NS) or amorphous (gold NS).
CONCLUSIONS
This nanostructure-synthesizing ability makes these isolates interesting candidates to get NS with biotechnological potential.
Topics: Aerobiosis; Anaerobiosis; Anti-Bacterial Agents; Biodegradation, Environmental; Cell Extracts; Exiguobacterium; Gold; Metal Nanoparticles; Microbial Sensitivity Tests; Silver; Tellurium; Temperature
PubMed: 32471409
DOI: 10.1186/s12896-020-00625-y -
Frontiers in Microbiology 2019Knowledge regarding bacterial dynamics during crop ensiling is important for understanding of the fermentation process and may facilitate the production of nutritious...
Knowledge regarding bacterial dynamics during crop ensiling is important for understanding of the fermentation process and may facilitate the production of nutritious and stable silage. The objective of this study was to analyze the bacterial dynamics associated with whole crop wheat silage with and without inoculants. Whole crop wheat was ensiled in laboratory silos, with and without inoculants (), for 3 months. Untreated and -treated silages were sampled at several times during ensiling, while -treated silage was sampled only at 3 months. Bacterial composition was studied using next generation sequencing approach. Dominant bacteria, before ensiling, were (34.7%), (28.4%) and (10.4%), (7.8%), and (3.4%). Exogenous inoculants significantly affected bacterial composition and dynamics during ensiling. At 3 months of ensiling, dominated the silage bacterial population and reached an abundance of 59.5, 92.5, and 98.2% in untreated, - and -treated silages, respectively. The bacterial diversity of the mature silage was lower in both treated silages compared to untreated silage. Functional profiling of the bacterial communities associated with the wheat ensiling demonstrated that the abundant pathways of membrane transporters, carbohydrate and amino acids metabolisms followed different pattern of relative abundance in untreated and -treated silages. Only three pathways, namely base-excision repair, pyruvate metabolism and transcription machinery, were significantly different between untreated and -treated silages upon maturation. Lactic acid content was higher in treated silage compared to untreated and treated silage. Still, the pH of both treated silages was lower in the two -treated silages compared to untreated silage. Aerobic stability test demonstrated that -, but not -supplement, facilitated silage deterioration. The lower aerobic stability of the -treated silage may be attributed to lower content of acetic acid and other volatile fatty acids which inhibit aerobic yeasts and molds. Indeed, high yeast count was recorded, following exposure to air, only in -treated silage, supporting this notion. Analysis of bacterial community of crop silage can be used for optimization of the ensiling process and the selection of appropriate inoculants for improving aerobic stability.
PubMed: 31354651
DOI: 10.3389/fmicb.2019.01532 -
Genome Biology and Evolution Mar 2018Exiguobacterium and Psychrobacter are bacterial genera with several cold-adapted species. These extremophiles are commonly isolated from the same habitats in Earth's...
Exiguobacterium and Psychrobacter are bacterial genera with several cold-adapted species. These extremophiles are commonly isolated from the same habitats in Earth's cryosphere and have great ecological and biotechnological relevance. Thus, through comparative genomic analyses, it was possible to understand the functional diversity of these psychrotrophic and psychrophilic species and present new insights into the microbial adaptation to cold. The nucleotide identity between Exiguobacterium genomes was >90%. Three genomic islands were identified in the E. antarcticum B7 genome. These islands contained genes involved in flagella biosynthesis and chemotaxis, as well as enzymes for carotenoid biosynthesis. Clustering of cold shock proteins by Ka/Ks ratio suggests the occurrence of a positive selection over these genes. Neighbor-joining clustering of complete genomes showed that the E. sibiricum was the most closely related to E. antarcticum. A total of 92 genes were shared between Exiguobacterium and Psychrobacter. A reduction in the genomic content of E. antarcticum B7 was observed. It presented the smallest genome size of its genus and a lower number of genes because of the loss of many gene families compared with the other genomes. In our study, eight genomes of Exiguobacterium and Psychrobacter were compared and analysed. Psychrobacter showed higher genomic plasticity and E. antarcticum B7 presented a large decrease in genomic content without changing its ability to grow in cold environments.
Topics: Adaptation, Physiological; Bacillales; Cold Temperature; Genome, Bacterial; Phylogeny; Psychrobacter; Sequence Analysis, DNA
PubMed: 29438502
DOI: 10.1093/gbe/evy029 -
Journal of Hazardous Materials Jun 2024Aquatic microplastics (MPs) act as reservoirs for microbial communities, fostering the formation of a mobile resistome encompassing diverse antibiotic (ARGs) and...
Aquatic microplastics (MPs) act as reservoirs for microbial communities, fostering the formation of a mobile resistome encompassing diverse antibiotic (ARGs) and biocide/metal resistance genes (BMRGs), and mobile genetic elements (MGEs). This collective genetic repertoire, referred to as the "plastiome," can potentially perpetuate environmental antimicrobial resistance (AMR). Our study examining two Japanese rivers near Tokyo revealed that waterborne MPs are primarily composed of polyethylene and polypropylene fibers and sheets of diverse origin. Clinically important genera like Exiguobacterium and Eubacterium were notably enriched on MPs. Metagenomic analysis uncovered a 3.46-fold higher enrichment of ARGs on MPs than those in water, with multidrug resistance genes (MDRGs) and BMRGs prevailing, particularly within MPs. Specific ARG and BMRG subtypes linked to resistance to vancomycin, beta-lactams, biocides, arsenic, and mercury showed selective enrichment on MPs. Network analysis revealed intense associations between host genera with ARGs, BMRGs, and MGEs on MPs, emphasizing their role in coselection. In contrast, river water exhibited weaker associations. This study underscores the complex interactions shaping the mobile plastiome in aquatic environments and emphasizes the global imperative for research to comprehend and effectively control AMR within the One Health framework.
Topics: Rivers; Microplastics; Anti-Bacterial Agents; Water Pollutants, Chemical; Bacteria; Water Microbiology; Interspersed Repetitive Sequences; Genes, Bacterial; Drug Resistance, Bacterial; Disinfectants; Microbiota; Drug Resistance, Microbial
PubMed: 38678707
DOI: 10.1016/j.jhazmat.2024.134353 -
Frontiers in Microbiology 2018Extremophiles are organisms capable of adjust, survive or thrive in hostile habitats that were previously thought to be adverse or lethal for life. Chile gathers a wide... (Review)
Review
Extremophiles are organisms capable of adjust, survive or thrive in hostile habitats that were previously thought to be adverse or lethal for life. Chile gathers a wide range of extreme environments: salars, geothermal springs, and geysers located at Altiplano and Atacama Desert, salars and cold mountains in Central Chile, and ice fields, cold lakes and fjords, and geothermal sites in Patagonia and Antarctica. The aims of this review are to describe extremophiles that inhabit main extreme biotopes in Chile, and their molecular and physiological capabilities that may be advantageous for bioremediation processes. After briefly describing the main ecological niches of extremophiles along Chilean territory, this review is focused on the microbial diversity and composition of these biotopes microbiomes. Extremophiles have been isolated in diverse zones in Chile that possess extreme conditions such as Altiplano, Atacama Desert, Central Chile, Patagonia, and Antarctica. Interesting extremophiles from Chile with potential biotechnological applications include thermophiles (e.g., from Tatio Geyser), acidophiles (e.g., from Atacama Desert and Central Chile copper ores), halophiles (e.g., sp. Asc-3 from Altiplano, sp. HKF-8 from Patagonia), alkaliphiles ( sp. SH31 from Altiplano), xerotolerant bacteria ( from Atacama Desert), UV- and Gamma-resistant bacteria ( from Atacama Desert) and psychrophiles (e.g., ATH-43 from Antarctica). The molecular and physiological properties of diverse extremophiles from Chile and their application in bioremediation or waste treatments are further discussed. Interestingly, the remarkable adaptative capabilities of extremophiles convert them into an attractive source of catalysts for bioremediation and industrial processes.
PubMed: 30425685
DOI: 10.3389/fmicb.2018.02309 -
International Journal of Environmental... Feb 2022The COVID-19 pandemic made more people aware of the danger of viruses and bacteria, which is why disinfection began to be used more and more often. Epidemiological...
The COVID-19 pandemic made more people aware of the danger of viruses and bacteria, which is why disinfection began to be used more and more often. Epidemiological safety must be ensured not only in gathering places, but also in home and work environments. It is especially challenging in public transportation, which is a perfect environment for the spread of infectious disease. Therefore, the aim of the study was the identification of bacteria in crowded places and the evaluation of the effect of fumigation with peracetic acid (PAA) in public transportation. Inactivation of microorganisms in buses and long-distance coaches was carried out using an automatic commercial fogging device filled with a solution of peracetic acid stabilized with acetic acid (AA) and hydrogen peroxide (HO). Before and after disinfection, samples were taken for microbiological tests. The most prevalent bacteria were and was only present in buses, whereas and were only present in coaches. Statistical analysis showed a significant reduction in the number of microorganisms in samples taken from different surfaces after disinfection in vehicles. The overall effectiveness of disinfection was 81.7% in buses and 66.5% in coaches. Dry fog fumigation with peracetic acid is an effective method of disinfecting public transport vehicles.
Topics: COVID-19; Disinfectants; Fumigation; Humans; Hydrogen Peroxide; Pandemics; Peracetic Acid; SARS-CoV-2
PubMed: 35270221
DOI: 10.3390/ijerph19052526 -
BMC Infectious Diseases Jul 2017Bacterial species belonging to the genus Exiguobacterium are facultative anaerobic, non-spore-forming, Gram-positive bacilli, and rarely associated with human... (Review)
Review
BACKGROUND
Bacterial species belonging to the genus Exiguobacterium are facultative anaerobic, non-spore-forming, Gram-positive bacilli, and rarely associated with human infections. Herein, we reported the first case of community-acquired pneumonia (CAP) and bacteremia due to Exiguobacterium spp. in China.
CASE PRESENTATION
An adult male with severe CAP was hospitalized. The pathogen was isolated from his bloodstream and broncho-alveolar lavage fluid. The correct identification of the micro-organism was achieved using 16S rRNA sequencing, and its antibiotic susceptibility test was performed by microdilution method. The Whole Genome Sequencing (WGS) was used to characterize its genetic features and to elucidate its potential pathogenic mechanisms. Furthermore, its genome sequence was also compared with those of 3 publicly-available Exiguobacterium strains. A PubMed search was performed for further understanding the features of Exiguobacterium infections. Phylogenetic analysis of the 16S rRNA gene sequence showed that the strain GX59 was most closely related to Exiguobacterium AT1b (99.7%). The genome of GX59 was 2,727,929 bp in size, harbouring 2855 putative protein-coding genes, 5 rRNA operons, 37 tRNA genes and 1 tmRNA. The multiple genome comparison of 4 Exiguobacterium strains demonstrated that Exiguobacterium contained 37 genes of secretion systems, including sec, tat, FEA, Type IV Pili and competence-related DNA transformation transporter (Com). Virulence factors of the micro-organism included tlyC, NprR, MCP, Dam, which might play a critical role in causing lethal infection.
CONCLUSIONS
The study highlighted the potential pathogenicity of the genus Exiguobacterium for its unique genes encoding various virulence factors and those associated with antibiotic resistance, therefore, its clinical significance should be valued.
Topics: Bacillaceae; Bacteremia; China; Community-Acquired Infections; DNA, Bacterial; Diabetes Mellitus, Type 2; Genome, Bacterial; Humans; Male; Middle Aged; Phylogeny; Pneumonia, Bacterial; RNA, Ribosomal, 16S
PubMed: 28732529
DOI: 10.1186/s12879-017-2616-1 -
Biophysical Reviews Aug 2022Microbial rhodopsins are the family of retinal-containing proteins that perform primarily the light-driven transmembrane ion transport and sensory functions. They are... (Review)
Review
Microbial rhodopsins are the family of retinal-containing proteins that perform primarily the light-driven transmembrane ion transport and sensory functions. They are widely distributed in nature and can be used for optogenetic control of the cellular activities by light. Functioning of microbial rhodopsins results in generation of the transmembrane electric potential in response to a flash that can be measured by direct time-resolved electrometry. This method was developed by L. Drachev and his colleagues at the Belozersky Institute and successfully applied in the functional studies of microbial rhodopsins. First measurements were performed using bacteriorhodopsin from -the prototype member of the microbial retinal protein family. Later, direct electrometric studies were conducted with proteorhodopsin from (ESR), the sodium pump from , and other proteins. They allowed detailed characterization of the charge transfer steps during the photocycle of microbial rhodopsins and provided new insights for profound understanding of their mechanism of action.
PubMed: 36124261
DOI: 10.1007/s12551-022-00986-y -
Microorganisms Nov 2021The highly xerotolerant bacterium classified as sp. Helios isolated from a solar panel in Spain showed a close relationship to 255-15 isolated from Siberian...
The highly xerotolerant bacterium classified as sp. Helios isolated from a solar panel in Spain showed a close relationship to 255-15 isolated from Siberian permafrost. Xerotolerance has not been previously described as a characteristic of the extremely diverse genus, but both strains Helios and 255-15 showed higher xerotolerance than that described in the reference xerotolerant model strain . Significant changes observed in the cell morphology after their desiccation suggests that the structure of cellular surface plays an important role in xerotolerance. Apart from its remarkable resistance to desiccation, sp. Helios strain shows several polyextremophilic characteristics that make it a promising chassis for biotechnological applications. sp. Helios cells produce nanoparticles of selenium in the presence of selenite linked to its resistance mechanism. Using the plasmid pRCR12 that harbors a cherry marker, we have developed a transformation protocol for sp. Helios strain, being the first time that a bacterium of genus has been genetically modified. The comparison of sp. Helios and 255-15 genomes revealed several interesting similarities and differences. Both strains contain a complete set of competence-related DNA transformation genes, suggesting that they might have natural competence, and an incomplete set of genes involved in sporulation; moreover, these strains not produce spores, suggesting that these genes might be involved in xerotolerance.
PubMed: 34946057
DOI: 10.3390/microorganisms9122455