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Applied and Environmental Microbiology Oct 2020Cr(VI) is mutagenic and teratogenic and considered an environmental pollutant of increasing concern. The use of microbial enzymes that convert this ion into its less...
Cr(VI) is mutagenic and teratogenic and considered an environmental pollutant of increasing concern. The use of microbial enzymes that convert this ion into its less toxic reduced insoluble form, Cr(III), represents a valuable bioremediation strategy. In this study, we examined the YhdA enzyme, which belongs to the family of NADPH-dependent flavin mononucleotide oxide reductases and possesses azo-reductase activity as a factor that upon overexpression confers protection on from the cytotoxic effects promoted by Cr(VI) and counteracts the mutagenic effects of the reactive oxygen species (ROS)-promoted lesion 8-OxoG. Further, our assays unveiled catalytic and biochemical properties of biotechnological relevance in YhdA; a pure recombinant His-YhdA protein efficiently catalyzed the reduction of Cr(VI) employing NADPH as a cofactor. The activity of the pure oxidoreductase YhdA was optimal at 30°C and at pH 7.5 and displayed and values of 7.26 mM and 26.8 μmol·min·mg for Cr(VI), respectively. Therefore, YhdA can be used for efficient bioremediation of Cr(VI) and counteracts the cytotoxic and genotoxic effects of oxygen radicals induced by intracellular factors and those generated during reduction of hexavalent chromium. Here, we report that the bacterial flavin mononucleotide/NADPH-dependent oxidoreductase YhdA, widely distributed among Gram-positive bacilli, conferred protection to cells from the cytotoxic effects of Cr(VI) and prevented the hypermutagenesis exhibited by a MutT/MutM/MutY-deficient strain. Additionally, a purified recombinant His-YhdA protein displayed a strong NADPH-dependent chromate reductase activity. Therefore, we postulate that in bacterial cells, YhdA counteracts the cytotoxic and genotoxic effects of intracellular and extracellular inducers of oxygen radicals, including those caused by hexavalent chromium.
Topics: Bacillus subtilis; Bacterial Proteins; Chromium; FMN Reductase
PubMed: 32801174
DOI: 10.1128/AEM.01688-20 -
Journal of Bacteriology Jun 2021The dispersal of bacterial cells from a matured biofilm can be mediated either by active or passive mechanisms. In this issue of the , Nishikawa and Kobayashi...
The dispersal of bacterial cells from a matured biofilm can be mediated either by active or passive mechanisms. In this issue of the , Nishikawa and Kobayashi demonstrate that the presence of calcium influences the dispersal of spores from the pellicle biofilm of Bacillus subtilis (M. Nishikawa and K. Kobayashi, J Bacteriol 203:e00114-21, 2021, https://doi.org/10.1128/JB.00114-21). The authors propose that temporal heterogeneity in matrix production and chelation of calcium by dipicolinic acid in spores weakens the biofilm matrix and causes passive dispersal.
Topics: Bacillus subtilis; Biofilms; Calcium; Spores, Bacterial
PubMed: 33927051
DOI: 10.1128/JB.00192-21 -
Applied and Environmental Microbiology Oct 2020Iron (Fe) is one of the most important micronutrients for most life forms on earth. While abundant in soil, Fe bioavailability in oxic soil is very low. Under...
Iron (Fe) is one of the most important micronutrients for most life forms on earth. While abundant in soil, Fe bioavailability in oxic soil is very low. Under environmental conditions, bacteria need to acquire sufficient Fe to sustain growth while limiting the energy cost of siderophore synthesis. Biofilm formation might mitigate this Fe stress, since it was shown to accumulate Fe in certain Gram-negative bacteria and that this Fe could be mobilized for uptake. However, it is still unclear if, and to what extent, the amount of Fe accumulated in the biofilm can sustain growth and if the mobilization of this local Fe pool is modulated by the availability of environmental Fe (i.e., Fe outside the biofilm matrix). Here, we use a nondomesticated strain of the ubiquitous biofilm-forming soil bacterium and stable Fe isotopes to precisely evaluate the origin of Fe during growth in the presence of tannic acid and hydroxides, used as proxies for different environmental conditions. We report that this strain can accumulate a large quantity of Fe in the biofilm, largely exceeding Fe associated with cells. We also report that only a fraction of biofilm-bound Fe is available for uptake in the absence of other sources of Fe in the vicinity of the biofilm. We observed that the availability of environmental Fe modulates the usage of this pool of biofilm-bound Fe. Finally, our data suggest that consumption of biofilm-bound Fe relates to the efficacy of to transport Fe from the environment to the biofilm, possibly through siderophores. Recent pieces of evidence suggest that Fe bound to the biofilm could assume at least two important functions, a local source of Fe for uptake and a support to extracellular metabolism, such as extracellular electron transfer. Our results show that can use biofilm-bound Fe for uptake only if it does not compromise Fe homeostasis of the biofilm, i.e., maintains a minimum Fe concentration in the biofilm for extracellular purposes. We propose a theoretical framework based on our results and recent literature to explain how manages biofilm-bound Fe and Fe uptake in response to environmental Fe availability. These results provide important insights into the management of biofilm-bound and environmental Fe by in response to Fe stress.
Topics: Bacillus subtilis; Biofilms; Biological Transport; Iron
PubMed: 32917750
DOI: 10.1128/AEM.00944-20 -
FEBS Letters Jun 1996The international programme to sequence the 4.2 Mb genome of Bacillus subtilis, a model Gram-positive bacterium, is a joint project involving European, Japanese and US... (Review)
Review
The international programme to sequence the 4.2 Mb genome of Bacillus subtilis, a model Gram-positive bacterium, is a joint project involving European, Japanese and US research groups. To date ca. 3.0 Mb of the genome has been sequenced, with the remaining 1.2 Mb expected to be completed in 1997. The amenability of B.subtilis to genetic manipulation, combined with the availability of extensive expertise on its biochemistry and physiology, makes this bacterium a valuable organism in which to investigate the properties of genes for which functions cannot be readily ascribed by standard methods.
Topics: Bacillus subtilis; Genome, Bacterial; Sequence Analysis, DNA
PubMed: 8682212
DOI: 10.1016/0014-5793(96)00524-8 -
MicrobiologyOpen Jun 2021Natural isolates of the soil-dwelling bacterium Bacillus subtilis form robust biofilms under laboratory conditions and colonize plant roots. B. subtilis biofilm gene...
Natural isolates of the soil-dwelling bacterium Bacillus subtilis form robust biofilms under laboratory conditions and colonize plant roots. B. subtilis biofilm gene expression displays phenotypic heterogeneity that is influenced by a family of Rap-Phr regulatory systems. Most Rap-Phr systems in B. subtilis have been studied independently, in different genetic backgrounds and under distinct conditions, hampering true comparison of the Rap-Phr systems' impact on bacterial cell differentiation. Here, we investigated each of the 12 Rap-Phr systems of B.subtilis NCIB 3610 for their effect on biofilm formation. By studying single ∆rap-phr mutants, we show that despite redundancy between the cell-cell communication systems, deletion of each of the 12 Rap-Phr systems influences matrix gene expression. These Rap-Phr systems therefore enable fine-tuning of the timing and level of matrix production in response to specific conditions. Furthermore, some of the ∆rap-phr mutants demonstrated altered biofilm formation in vitro and colonization of Arabidopsis thaliana roots, but not necessarily similarly in both processes, indicating that the pathways regulating matrix gene expression and other factors important for biofilm formation may be differently regulated under these distinct conditions.
Topics: Arabidopsis; Bacillus subtilis; Bacterial Proteins; Biofilms; Gene Deletion; Gene Expression Regulation, Bacterial; Plant Roots
PubMed: 34180604
DOI: 10.1002/mbo3.1212 -
Journal of Bacteriology Dec 2011The cotG and cotH genes of Bacillus subtilis encode two previously characterized spore coat proteins. The two genes are adjacent on the chromosome and divergently...
The cotG and cotH genes of Bacillus subtilis encode two previously characterized spore coat proteins. The two genes are adjacent on the chromosome and divergently transcribed by σ(K), a sporulation-specific σ factor of the RNA polymerase. We report evidence that the cotH promoter maps 812 bp upstream of the beginning of its coding region and that the divergent cotG gene is entirely contained between the promoter and the coding part of cotH. A bioinformatic analysis of all entirely sequenced prokaryotic genomes showed that such chromosomal organization is not common in spore-forming bacilli. Indeed, CotG is present only in B. subtilis, B. amyloliquefaciens, and B. atrophaeus and in two Geobacillus strains. When present, cotG always encodes a modular protein composed of tandem repeats and is always close to but divergently transcribed with respect to cotH. Bioinformatic and phylogenic data suggest that such genomic organizations have a common evolutionary origin and that the modular structure of the extant cotG genes is the outcome of multiple rounds of gene elongation events of an ancestral minigene.
Topics: Amino Acid Sequence; Bacillus subtilis; Bacterial Proteins; Base Sequence; Evolution, Molecular; Gene Expression Regulation, Bacterial; Molecular Sequence Data; Promoter Regions, Genetic; Sequence Alignment; Spores, Bacterial
PubMed: 21984783
DOI: 10.1128/JB.06121-11 -
Applied and Environmental Microbiology Feb 2009Acid and base environmental stress responses were investigated in Bacillus subtilis. B. subtilis AG174 cultures in buffered potassium-modified Luria broth were switched...
Acid and base environmental stress responses were investigated in Bacillus subtilis. B. subtilis AG174 cultures in buffered potassium-modified Luria broth were switched from pH 8.5 to pH 6.0 and recovered growth rapidly, whereas cultures switched from pH 6.0 to pH 8.5 showed a long lag time. Log-phase cultures at pH 6.0 survived 60 to 100% at pH 4.5, whereas cells grown at pH 7.0 survived <15%. Cells grown at pH 9.0 survived 40 to 100% at pH 10, whereas cells grown at pH 7.0 survived <5%. Thus, growth in a moderate acid or base induced adaptation to a more extreme acid or base, respectively. Expression indices from Affymetrix chip hybridization were obtained for 4,095 protein-encoding open reading frames of B. subtilis grown at external pH 6, pH 7, and pH 9. Growth at pH 6 upregulated acetoin production (alsDS), dehydrogenases (adhA, ald, fdhD, and gabD), and decarboxylases (psd and speA). Acid upregulated malate metabolism (maeN), metal export (czcDO and cadA), oxidative stress (catalase katA; OYE family namA), and the SigX extracytoplasmic stress regulon. Growth at pH 9 upregulated arginine catabolism (roc), which generates organic acids, glutamate synthase (gltAB), polyamine acetylation and transport (blt), the K(+)/H(+) antiporter (yhaTU), and cytochrome oxidoreductases (cyd, ctaACE, and qcrC). The SigH, SigL, and SigW regulons were upregulated at high pH. Overall, greater genetic adaptation was seen at pH 9 than at pH 6, which may explain the lag time required for growth shift to high pH. Low external pH favored dehydrogenases and decarboxylases that may consume acids and generate basic amines, whereas high external pH favored catabolism-generating acids.
Topics: Acids; Adaptation, Physiological; Alkalies; Anti-Bacterial Agents; Bacillus subtilis; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Microbial Viability
PubMed: 19114526
DOI: 10.1128/AEM.01652-08 -
MBio Aug 2021Bacteriophage predation is an important factor in bacterial community dynamics and evolution. Phage-bacterium interaction has mainly been studied in lab cultures, while...
Bacteriophage predation is an important factor in bacterial community dynamics and evolution. Phage-bacterium interaction has mainly been studied in lab cultures, while dynamics in natural habitats, and especially in the plant root niche, are underexplored. To better understand this process, we characterized infection of the soil bacterium Bacillus subtilis NCBI 3610 by the lytic phage SPO1 during growth in LB medium and compared it to root colonization. Resistance was primarily through modification of the phage receptor. However, this type of resistance reduced the ability to colonize the root. From a line that survived phage infection while retaining the ability to colonize the root, we identified a new phage resistance mechanism involving potassium (K) ion influx modulation and enhanced biofilm formation. Furthermore, we show that potassium serves as a stimulator of root colonization among diverse growth-promoting bacilli species, with implications for plant health. Bacteriophage predation is an important factor in bacterial community dynamics and evolution. Phage-bacterium interaction has mainly been studied in lab cultures, while dynamics in natural habitats, and especially in the plant root niche, are underexplored. To better understand this process, we characterized infection of the soil bacterium Bacillus subtilis NCBI 3610 by the lytic phage SPO1 during growth in LB medium and compared it to root colonization. Resistance was primarily through modification of the phage receptor. However, this type of resistance reduced the ability to colonize the root. From a line that survived phage infection while retaining the ability to colonize the root, we identified a new phage resistance mechanism involving potassium (K+) ion influx modulation and enhanced biofilm formation. Furthermore, we show that potassium serves as a stimulator of root colonization among diverse growth-promoting bacilli species, with implications for plant health.
Topics: Bacillus subtilis; Bacteriophages; Biofilms; Microbial Interactions; Plant Roots; Potassium; Soil Microbiology
PubMed: 34399609
DOI: 10.1128/mBio.01403-21 -
Yakugaku Zasshi : Journal of the... 2012The Gram-positive bacterium Bacillus subtilis forms spores when conditions are unsuitable for growth. The spores are encased in a multilayered shell that includes a... (Review)
Review
The Gram-positive bacterium Bacillus subtilis forms spores when conditions are unsuitable for growth. The spores are encased in a multilayered shell that includes a cortex and a spore coat, and remain viable for long periods in the harsh environment. In the present article, recent progress in our understanding of the outer structure of B. subtilis spores is reviewed in the Japanese language. Although spore coat assembly involves the deposition of at least 70 distinct protein species, the positions of most of such proteins have not been experimentally determined. To this end, the diameters of the protein layers and spores were measured using fluorescence microscopy and then the positions of proteins in the spore coat of B. subtilis spores were estimated. The locations of 16 proteins were determined using this method. One protein was assigned to the cortex, nine to the inner coat, and four to the outer coat. Further, two proteins, CgeA and CotZ, were assigned to a previously unidentified outermost layer. McKenney et al. have also identified the outermost layer using a similar method; the layer was termed the "crust". Immunofluorescence microscopy revealed that the crust is indeed the most external layer of B. subtilis spores. Mutational analysis indicated that all genes in the cotVWXYZ cluster were involved in spore crust synthesis and that CotY and CotZ played critical roles in crust formation.
Topics: Bacillus subtilis; Bacterial Proteins; Microscopy, Fluorescence; Multigene Family; Mutation; Spores, Bacterial
PubMed: 22864350
DOI: 10.1248/yakushi.132.919 -
Current Topics in Microbiology and... 2008Our understanding of the molecular mechanisms involved in biofilm formation has increased tremendously in recent years. From research on diverse bacteria, a general... (Review)
Review
Our understanding of the molecular mechanisms involved in biofilm formation has increased tremendously in recent years. From research on diverse bacteria, a general model of bacterial biofilm development has emerged. This model can be adjusted to fit either of two common modes of unicellular existence: nonmotile and motile. Here we provide a detailed review of what is currently known about biofilm formation by the motile bacterium Bacillus subtilis. While the ability of bacteria to form a biofilm appears to be almost universal and overarching themes apply, the combination of molecular events necessary varies widely, and this is reflected in the other chapters of this book.
Topics: Bacillus subtilis; Bacterial Adhesion; Biofilms
PubMed: 18453269
DOI: 10.1007/978-3-540-75418-3_1