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Frontiers in Microbiology 2020Anthropogenic perturbations introduce novel selective pressures to natural environments, impacting the genomic variability of organisms and thus altering the...
Anthropogenic perturbations introduce novel selective pressures to natural environments, impacting the genomic variability of organisms and thus altering the evolutionary trajectory of populations. Water overexploitation for agricultural purposes and defective policies in Cuatro Cienegas, Coahuila, Mexico, have strongly impacted its water reservoir, pushing entire hydrological systems to the brink of extinction along with their native populations. Here, we studied the effects of continuous water overexploitation on an environmental aquatic lineage of over a 13-year period which encompasses three desiccation events. By comparing the genomes of a population sample from 2003 (original state) and 2015 (perturbed state), we analyzed the demographic history and evolutionary response to perturbation of this lineage. Through coalescent simulations, we obtained a demographic model of contraction-expansion-contraction which points to the occurrence of an evolutionary rescue event. Loss of genomic and nucleotide variation alongside an increment in mean and variance of Tajima's , characteristic of sudden population expansions, support this observation. In addition, a significant increase in recombination rate (R/θ) was observed, pointing to horizontal gene transfer playing a role in population recovery. Furthermore, the gain of phosphorylation, DNA recombination, small-molecule metabolism and transport and loss of biosynthetic and regulatory genes suggest a functional shift in response to the environmental perturbation. Despite subsequent sampling events in the studied site, no pseudomonad was found until the lagoon completely dried in 2017. We speculate about the causes of final decline or possible extinction. Overall our results are evidence of adaptive responses at the genomic level of bacterial populations in a heavily exploited aquifer.
PubMed: 33552002
DOI: 10.3389/fmicb.2020.563885 -
Pathogens (Basel, Switzerland) Feb 2021causes deadly primary amoebic meningoencephalitis (PAM) in humans. Humans obtain the infection by inhaling water or dust contaminated with amebae into the nostrils,...
causes deadly primary amoebic meningoencephalitis (PAM) in humans. Humans obtain the infection by inhaling water or dust contaminated with amebae into the nostrils, wherefrom the pathogen migrates via the olfactory nerve to cause brain inflammation and necrosis. Current PAM treatment is ineffective and toxic. Seeking new effective and less toxic drugs for the environmental control of the amoeba population to reduce human exposure is logical for the management of infection. On the basis of the concept of competitive exclusion, where environmental microorganisms compete for resources by secreting factors detrimental to other organisms, we tested cell-free culture supernatants (CFSs) of three bacteria isolated from a fresh water canal, i.e., , , and , were tested against . The CFSs inhibited growth and caused morphological changes in . At low dose, trophozoites exposed to pyocyanin were seen to shrink and become rounded, while at high dose, the trophozoites were fragmented. While the precise molecular mechanisms of pyocyanin and products of and that also exert anti- activity await clarification. Our findings suggest that pyocyanin may have a role in the control of amphizoic in the environment.
PubMed: 33535404
DOI: 10.3390/pathogens10020142 -
International Journal of Environmental... Jan 2021Recently, the application of endophytes in the alleviation of different types of stresses has received considerable attention, but their role in drought stress...
Recently, the application of endophytes in the alleviation of different types of stresses has received considerable attention, but their role in drought stress alleviation and growth promotion in soybean is not well-stated. In this study, twenty bacterial endophytes were isolated from soybean root tissues and screened for plant growth-promoting (PGP) traits, biocontrol potential, and drought stress alleviation. Out of them, 80% showed PGP traits, and 20% showed antagonistic activity against (ITCC 2389), (ITCC 1800), and (ITCC 3467), and only three of them showed drought tolerance up to 15% (-0.3 MPa). Results indicated that drought-tolerant PGP endophytic bacteria enhanced soybean seedling growth under drought stress conditions. Morphological, biochemical, and molecular characterization (16S rRNA) revealed that these three bacterial isolates, AKAD A1-1, AKAD A1-2, and AKAD A1-16, closely resemble (GenBank accession No. MN079048), (MW301101), and sp. (MN079074), respectively. We observed that the soybean seedlings were grown in well-watered and drought-stressed soil showed the adverse effect of drought stress on morphological (stem length, root length, plant fresh and dry weight) as well as on biochemical parameters (a decline of photosynthetic pigments, membrane damage, etc.). However, soybean seedlings inoculated with these endophytes have improved the biomass significantly ( ≤ 0.05) under normal as well as in drought stress conditions over control treatments by influencing several biochemical changes. Among these three endophytes, AKAD A1-16 performed better than AKAD A1-2 and AKAD A1-1, which was further validated by the ability to produce the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase in the following order: AKAD A1-16 > AKAD A1-2 > AKAD A1-1. Scanning electron microscopy images also showed a bacterial presence inside the roots of soybean seedlings. These findings supported the application of bacterial root endophytes as a potential tool to mitigate the effect of drought as well as of fungal diseases on the early seedling growth of soybean.
Topics: Alternaria; Ascomycota; Bacteria; Droughts; Endophytes; Fusarium; Plant Roots; Pseudomonas; RNA, Ribosomal, 16S; Glycine max
PubMed: 33494513
DOI: 10.3390/ijerph18030931 -
Microbiological Research Nov 2020In this study, we have attempted to develop a plant growth promoting rhizobacteria (PGPR) consortia against early-stage diseases in Arachis hypogaea (Groundnut crop)...
In this study, we have attempted to develop a plant growth promoting rhizobacteria (PGPR) consortia against early-stage diseases in Arachis hypogaea (Groundnut crop) plantation of Andhra Pradesh, India. The dominant PGPRs were selected by considering the various plant growth and protection qualities, followed by characterisation and grouping based on compatibility to form a consortium of PGPRs [Group-1 includes EX-1 (Acinetobacter baumannii stain HAMBI 1846); EX-3 (Pseudomonas aeruginosa strain A1K319); EX-5 (Bacillus subterraneus strain CF1.9); KNL-1 (Bacillus subtilis strain JMP-B); CTR-4 (Enterobacter cloacae strain VITKJ1); ANT-4 (Bacillus subtilis strain SBMP4) and Group-2 includes EX-4 (Pseudomonas otitidis strain SLC8); KDP-4 (Pseudomonas aeruginosa strain Kasamber 11); NLR-4 (Bacillus species ADMK68); ANT-6 (Bacillus subtilis subsp. inaquosorum strain KCTC 13429)]. In addition to resistance to early stage pathogens, in both in vitro and pot experiments the PGPR consortium showed significantly higher germination rate and root induction (Aspergillus niger; A. flavus; Fusarium oxysporum) when compared to control and fertilizer treated groups. In addition, Group 2 was more successful in stimulating and protecting plant growth among the two groups of PGPRs developed. The PGPR consortia developed showed multiple plant growth characteristics, including phosphate solubilization, production of HCN and Indole acetic acid along with broad antagonism against the tested phytopathogens.
Topics: Acinetobacter baumannii; Arachis; Aspergillus; Aspergillus niger; Bacillus; Bacillus subtilis; Enterobacter cloacae; Fertilizers; Fusarium; India; Indoleacetic Acids; Pest Control; Plant Development; Plant Diseases; Pseudomonas; Pseudomonas aeruginosa; RNA, Ribosomal, 16S; Seeds; Soil Microbiology
PubMed: 32739583
DOI: 10.1016/j.micres.2020.126562 -
Microbiology Resource Announcements Apr 2020We isolated strain MrB4 from the near-shore area of Lake Biwa in Japan and generated its complete genome sequence. MrB4 possesses a single circular chromosome of...
We isolated strain MrB4 from the near-shore area of Lake Biwa in Japan and generated its complete genome sequence. MrB4 possesses a single circular chromosome of 6,089,454 bp, with ∼97% average nucleotide identity to the type strain MCC10330 (draft genome).
PubMed: 32299875
DOI: 10.1128/MRA.00148-20 -
International Health Sep 2020The present study was carried out to investigate the tap water quality of public toilets in Amritsar, Punjab, India.
BACKGROUND
The present study was carried out to investigate the tap water quality of public toilets in Amritsar, Punjab, India.
METHODS
Water samples from the taps of the public toilets were collected in sterile containers and physicochemical and bacteriological analysis was performed using standard methods. Also, genotypic and phenotypic characterization of the bacterial isolates was performed using different biochemical tests and 16S ribosomal RNA analysis. An antibiotic susceptibility test was performed using antibiotics based on their mode of action. A biofilm assay was performed to assess the adhesion potential of the isolates.
RESULTS
A total of 25 bacterial isolates were identified from the water samples, including Acinetobacter junii, Acinetobacter pittii, Acinetobacter haemolyticus, Bacillus pumilus, Bacillus megaterium, Bacillus marisflavi, Bacillus flexus, Bacillus oceanisediminis, Pseudomonas otitidis, Pseudomonas sp. RR013, Pseudomonas sp. RR021, Pseudomonas sp. RR022, Escherichia coli and Enterobacter cloacae. The results of the antimicrobial susceptibility test revealed that the antibiotics cefodroxil, aztreonam, nitrofurantoin, cefepime, ceftazidime and amoxyclav were found to be mostly ineffective against various isolates. The biofilm assay revealed the weak, moderate and strong biofilm producers among them.
CONCLUSIONS
The tap water in the public toilets was microbially contaminated and needs to be monitored carefully. The antibiotic susceptibility profile showed that of 25 bacterial isolates, 5 were multidrug resistant. Bacterial isolates exhibited strong to weak adhesion potential in the biofilm assay.
Topics: Acinetobacter; Anti-Bacterial Agents; Bacillus; Bacterial Infections; Bathroom Equipment; Biofilms; Genotype; Humans; India; Microbial Sensitivity Tests; Phenotype; Pseudomonas; Water; Water Microbiology
PubMed: 31693132
DOI: 10.1093/inthealth/ihz074 -
Journal of Global Antimicrobial... Jun 2020The presence of carbapenemase-producing bacterial isolates is found not only in hospital and community settings but also in the environment. Carbapenemase production may...
OBJECTIVES
The presence of carbapenemase-producing bacterial isolates is found not only in hospital and community settings but also in the environment. Carbapenemase production may be related to acquired, usually plasmid-borne, β-lactamase genes or to chromosomal genes intrinsic to various species. The aim of this study was to evaluate the occurrence of such carbapenemase-producing bacterial isolates among environmental samples from Nigeria.
METHODS
A total of 122 environmental samples were plated on carbapenem-containing media. A total of 259 isolates were recovered, among which 124 were carbapenemase-producers according to the results of the Rapidec® Carba NP test.
RESULTS
The majority of isolates (n=112) recovered corresponded to natural producers of carbapenemases, i.e. Stenotrophomonas maltophilia (n=108), Burkholderia cepacia (n=1), Shewanella sp. (n=1), Sphingobacterium sp. (n=1) and Chryseobacterium gleum (n=1). Ten isolates (mainly Enterobacteriaceae and Acinetobacter baumannii) produced an acquired carbapenemase, most commonly of the NDM type. In addition, two Pseudomonas otitidis isolates were identified as producing the Ambler class B carbapenemase POM-1, further confirming that this carbapenemase is naturally produced in this environmental species. Finally, several isolates co-producing 16S rRNA methylases (ArmA, RmtC) and/or extended-spectrum β-lactamases (CTX-M-9, CTX-M-15) were also identified.
CONCLUSION
This study revealed the presence and diversity of clinically-relevant antimicrobial-resistant bacteria in the environment in Nigeria.
Topics: Bacterial Proteins; Chryseobacterium; Nigeria; Pseudomonas; RNA, Ribosomal, 16S; beta-Lactamases
PubMed: 31639547
DOI: 10.1016/j.jgar.2019.10.014 -
Antimicrobial Agents and Chemotherapy Mar 2015The POM-1 metallo-β-lactamase is a subclass B3 resident enzyme produced by Pseudomonas otitidis, a pathogen causing otic infections. The enzyme was overproduced in...
The POM-1 metallo-β-lactamase is a subclass B3 resident enzyme produced by Pseudomonas otitidis, a pathogen causing otic infections. The enzyme was overproduced in Escherichia coli BL21(DE3), purified by chromatography, and subjected to structural and functional analysis. The purified POM-1 is a tetrameric enzyme of broad substrate specificity with higher catalytic activities with penicillins and carbapenems than with cephalosporins.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Carbapenems; Catalysis; Cephalosporins; Escherichia coli; Penicillins; Pseudomonas; beta-Lactamases
PubMed: 25512428
DOI: 10.1128/AAC.03843-14