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PloS One 2014Atrazine is a widely used herbicide with great environmental concern due to its high potential to contaminate soil and waters. An atrazine-degrading bacterial strain...
Atrazine is a widely used herbicide with great environmental concern due to its high potential to contaminate soil and waters. An atrazine-degrading bacterial strain HB-6 was isolated from industrial wastewater and the 16S rRNA gene sequencing identified HB-6 as a Bacillus subtilis. PCR assays indicated that HB-6 contained atrazine-degrading genes trzN, atzB and atzC. The strain HB-6 was capable of utilizing atrazine and cyanuric acid as a sole nitrogen source for growth and even cleaved the s-triazine ring and mineralized atrazine. The strain demonstrated a very high efficiency of atrazine biodegradation with a broad optimum pH and temperature ranges and could be enhanced by cooperating with other bacteria, suggesting its huge potential for remediation of atrazine-contaminated sites. To our knowledge, there are few Bacillus subtilis strains reported that can mineralize atrazine, therefore, the present work might provide some new insights on atrazine remediation.
Topics: Atrazine; Bacillus subtilis; Biodegradation, Environmental; Chromatography, High Pressure Liquid; Genes, Bacterial; Phylogeny; Triazines; Wastewater
PubMed: 25238246
DOI: 10.1371/journal.pone.0107270 -
Microbiology (Reading, England) Jan 2003Bacteria have developed a wide arsenal of survival strategies to cope with the specific problems posed by their environment. These processes are carefully regulated and... (Review)
Review
Bacteria have developed a wide arsenal of survival strategies to cope with the specific problems posed by their environment. These processes are carefully regulated and complex signal transduction cascades ensure proper activation of the adequate adaptive response. An intriguing observation is that generally the regulation pathways of the different adaptive processes are highly intertwined. In this review, this phenomenon is illustrated by the regulation of genetic competence development in Bacillus subtilis. The different regulation pathways which make up the gene regulation network that controls the development of competence are described, and their connections to other adaptive processes in B. subtilis are discussed.
Topics: Adaptation, Physiological; Bacillus subtilis; Bacterial Proteins; Gene Expression Regulation, Bacterial; Signal Transduction; Transcription Factors; Transformation, Bacterial
PubMed: 12576575
DOI: 10.1099/mic.0.26003-0 -
FEMS Microbiology Reviews Jan 2009Bacillus subtilis is a Gram-positive bacterium that is well known for its ability to differentiate into metabolically inactive spores that are highly resistant to... (Review)
Review
Bacillus subtilis is a Gram-positive bacterium that is well known for its ability to differentiate into metabolically inactive spores that are highly resistant to environmental stresses. In fact, populations of genetically identical B. subtilis comprise numerous distinct cell types. In addition to spores, cells can become genetically competent, motile, produce extracellular matrix or degradative enzymes, or secrete toxins that allow them to cannibalize their neighbors. Many of the cell fates listed above appear to be mutually exclusive. In this review, we discuss how individual cells within a population control their gene expression to ensure that proper regulation of differentiation occurs. These different cell fates are regulated by an intricate network that relies primarily on the activity of three major transcriptional regulators: Spo0A, DegU, and ComK. While individual cells must choose distinct cell fates, the population as a whole exhibits a spectrum of phenotypes whose diversity may increase fitness.
Topics: Bacillus subtilis; Bacterial Proteins; Biofilms; Gene Expression Regulation, Bacterial; Spores, Bacterial
PubMed: 19054118
DOI: 10.1111/j.1574-6976.2008.00148.x -
Journal of Bacteriology Aug 2016Many bacteria utilize actin-like proteins to direct peptidoglycan (PG) synthesis. MreB and MreB-like proteins are thought to act as scaffolds, guiding the localization...
UNLABELLED
Many bacteria utilize actin-like proteins to direct peptidoglycan (PG) synthesis. MreB and MreB-like proteins are thought to act as scaffolds, guiding the localization and activity of key PG-synthesizing proteins during cell elongation. Despite their critical role in viability and cell shape maintenance, very little is known about how the activity of MreB family proteins is regulated. Using a Bacillus subtilis misexpression screen, we identified two genes, yodL and yisK, that when misexpressed lead to loss of cell width control and cell lysis. Expression analysis suggested that yodL and yisK are previously uncharacterized Spo0A-regulated genes, and consistent with these observations, a ΔyodL ΔyisK mutant exhibited reduced sporulation efficiency. Suppressors resistant to YodL's killing activity occurred primarily in mreB mutants and resulted in amino acid substitutions at the interface between MreB and the highly conserved morphogenic protein RodZ, whereas suppressors resistant to YisK occurred primarily in mbl mutants and mapped to Mbl's predicted ATP-binding pocket. YodL's shape-altering activity appears to require MreB, as a ΔmreB mutant was resistant to the effects of YodL but not YisK. Similarly, YisK appears to require Mbl, as a Δmbl mutant was resistant to the cell-widening effects of YisK but not of YodL. Collectively, our results suggest that YodL and YisK likely modulate MreB and Mbl activity, possibly during the early stages of sporulation.
IMPORTANCE
The peptidoglycan (PG) component of the cell envelope confers structural rigidity to bacteria and protects them from osmotic pressure. MreB and MreB-like proteins are thought to act as scaffolds for PG synthesis and are essential in bacteria exhibiting nonpolar growth. Despite the critical role of MreB-like proteins, we lack mechanistic insight into how their activities are regulated. Here, we describe the discovery of two B. subtilis proteins, YodL and YisK, which modulate MreB and Mbl activities. Our data suggest that YodL specifically targets MreB, whereas YisK targets Mbl. The apparent specificities with which YodL and YisK are able to differentially target MreB and Mbl make them potentially powerful tools for probing the mechanics of cytoskeletal function in bacteria.
Topics: Bacillus subtilis; Bacterial Proteins; Gene Expression Regulation, Bacterial; Mutation; Spores, Bacterial
PubMed: 27215790
DOI: 10.1128/JB.00183-16 -
Applied and Environmental Microbiology Sep 2004Artisanal and industrial sausages were analyzed for their aerobic, heat-resistant microflora to assess whether new emerging pathogens could be present among Bacillus... (Comparative Study)
Comparative Study
Artisanal and industrial sausages were analyzed for their aerobic, heat-resistant microflora to assess whether new emerging pathogens could be present among Bacillus strains naturally contaminating cured meat products. Sixty-four isolates were characterized by randomly amplified polymorphic DNA (RAPD)-PCR and fluorescent amplified fragment length polymorphism (fAFLP). The biotypes, identified by partial 16S rRNA gene sequence analysis, belonged to Bacillus subtilis, Bacillus pumilus, and Bacillus amyloliquefaciens species. Both RAPD-PCR and fAFLP analyses demonstrated that a high genetic heterogeneity is present in the B. subtilis group even in strains harvested from the same source, making it possible to isolate 56 different biotypes. Moreover, fAFLP analysis made it possible to distinguish B. subtilis from B. pumilus strains. The strains were characterized for their toxigenic potential by molecular, physiological, and immunological techniques. Specific PCR analyses revealed the absence of DNA sequences related to HBL, BcET, NHE, and entFM Bacillus cereus enterotoxins and the enzymes sphingomyelinase Sph and phospholipase PI-PLC in all strains; also, the immunological analyses showed that Bacillus strains did not react with NHE- and HBL-specific antibodies. However, some isolates were found to be positive for hemolytic and lecithinase activity. The absence of toxigenic potential in Bacillus strains from the sausages analyzed indicates that these products can be considered safe under the processing conditions they were produced; however, great care should be taken when the ripening time is shortened, particularly in the case of traditional sausages, which could contain high amounts of Bacillus strains and possibly some B. cereus cells.
Topics: Bacillus; Bacillus subtilis; Base Sequence; DNA Primers; Italy; Meat Products; Molecular Sequence Data; Phylogeny; Polymerase Chain Reaction
PubMed: 15345396
DOI: 10.1128/AEM.70.9.5168-5176.2004 -
Yakugaku Zasshi : Journal of the... 2013This review documents my research for the past 29 years in the work of bacterial sporulation. The Gram-positive bacterium Bacillus subtilis forms spores when conditions... (Review)
Review
This review documents my research for the past 29 years in the work of bacterial sporulation. The Gram-positive bacterium Bacillus subtilis forms spores when conditions are unsuitable for growth. The mature spores remain for long periods of starvation and are resistant to harsh environment. This property is attributed mainly to the unique figures of spore's outer layers, spore coat. The protein composition of the spores was comprehensively analyzed by a combination of SDS-PAGE and LC-MS/MS. The total of 154 proteins were identified and 69 of them were novel. The expression of the genes encoding them was dependent on sporulation-specific sigma factors, σF, σE, σG and σK. The expression of a coat protein gene, cotS, was dependent on σK and GerE. CotE is essential for the assembly of CotS in the coat layer. Many coat genes were identified by reverse genetics and the regulation of the gene expression was studied in detail. Some cot genes are functioned in the resistance to heat and lysozyme, and some of the coat proteins are involved in the specificity of germinants. The yrbA is essential in spore development, yrbA deficient cells revealed abnormal figures of spore coat structure and changed the response to germinants. The location of 16 coat proteins was determined by the observation of fluorescence microscopy using fluorescence-labelled proteins. One protein was assigned to the cortex, nine to the inner coat, and four to the outer coat. In addition, CotZ and CgeA appeared in the outermost layer of the spore coat.
Topics: Bacillus subtilis; Spores, Bacterial
PubMed: 23811766
DOI: 10.1248/yakushi.13-00143 -
Applied and Environmental Microbiology Jun 2011Five batch cultures of Bacillus subtilis were subjected to evolution in the laboratory for 6,000 generations under conditions repressing sporulation in complex liquid...
Five batch cultures of Bacillus subtilis were subjected to evolution in the laboratory for 6,000 generations under conditions repressing sporulation in complex liquid medium containing glucose. Between generations 1,000 and 2,000, variants with a distinct small-colony morphology arose and swept through four of the five populations that had been previously noted for their loss of sporulation (H. Maughan et al., Genetics 177:937-948, 2007). To better understand the nature of adaptation in these variants, individual strains were isolated from one population before (WN715) and after (WN716) the sweep. In addition to colony morphology, strains WN715 and WN716 differed in their motility, aerotaxis, and cell morphology. Competition experiments showed that strain WN716 had evolved a distinct fitness advantage over the ancestral strain and strain WN715 during growth and the transition to the postexponential growth phase, which was more pronounced when WN715 was present in the coculture. Microarray analyses revealed candidate genes in which mutations may have produced some of the observed phenotypes. For example, loss of motility in WN716 was accompanied by decreased transcription of all flagellar, motility, and chemotaxis genes on the microarray. Transcription of alsS and alsD was also lower in strain WN716, and the predicted loss of acetoin production and enhanced acetate production was confirmed by high-performance liquid chromatography (HPLC) analysis. The results suggested that the derived colony morphology of strain WN716 was associated with increased fitness, the alteration of several metabolic pathways, and the loss of a typical postexponential-phase response.
Topics: Adaptation, Biological; Bacillus subtilis; Chemotaxis; DNA, Bacterial; Gene Expression Profiling; Locomotion; Metabolic Networks and Pathways; Stress, Physiological
PubMed: 21531833
DOI: 10.1128/AEM.00374-11 -
Molecular Microbiology Apr 1999Nitrogen metabolism genes of Bacillus subtilis are regulated by the availability of rapidly metabolizable nitrogen sources, but not by any mechanism analogous to the... (Review)
Review
Nitrogen metabolism genes of Bacillus subtilis are regulated by the availability of rapidly metabolizable nitrogen sources, but not by any mechanism analogous to the two-component Ntr regulatory system found in enteric bacteria. Instead, at least three regulatory proteins independently control the expression of gene products involved in nitrogen metabolism in response to nutrient availability. Genes expressed at high levels during nitrogen-limited growth are controlled by two related proteins, GlnR and TnrA, which bind to similar DNA sequences under different nutritional conditions. The TnrA protein is active only during nitrogen limitation, whereas GlnR-dependent repression occurs in cells growing with excess nitrogen. Although the nitrogen signal regulating the activity of the GlnR and TnrA proteins is not known, the wild-type glutamine synthetase protein is required for the transduction of this signal to the GlnR and TnrA proteins. Examination of GlnR- and TnrA-regulated gene expression suggests that these proteins allow the cell to adapt to growth during nitrogen-limited conditions. A third regulatory protein, CodY, controls the expression of several genes involved in nitrogen metabolism, competence and acetate metabolism in response to growth rate. The highest levels of CodY-dependent repression occur in cells growing rapidly in a medium rich in amino acids, and this regulation is relieved during the transition to nutrient-limited growth. While the synthesis of amino acid degradative enzymes in B. subtilis is substrate inducible, their expression is generally not regulated in response to nitrogen availability by GlnR and TnrA. This pattern of regulation may reflect the fact that the catabolism of amino acids produced by proteolysis during sporulation and germination provides the cell with substrates for energy production and macromolecular synthesis. As a result, expression of amino acid degradative enzymes may be regulated to ensure that high levels of these enzymes are present in sporulating cells and in dormant spores.
Topics: Bacillus subtilis; Gene Expression Regulation, Bacterial; Genes, Bacterial; Nitrogen
PubMed: 10231480
DOI: 10.1046/j.1365-2958.1999.01333.x -
Microbiology (Reading, England) Nov 2016Bacillus subtilis is an intensively studied Gram-positive bacterium that has become one of the models for biofilm development. B. subtilis 168 is a well-known...
Bacillus subtilis is an intensively studied Gram-positive bacterium that has become one of the models for biofilm development. B. subtilis 168 is a well-known domesticated strain that has been suggested to be deficient in robust biofilm formation. Moreover, the diversity of available B. subtilis laboratory strains and their derivatives have made it difficult to compare independent studies related to biofilm formation. Here, we analysed numerous 168 stocks from multiple laboratories for their ability to develop biofilms in different set-ups and media. We report a wide variation among the biofilm-forming capabilities of diverse stocks of B. subtilis 168, both in architecturally complex colonies and liquid-air interface pellicles, as well as during plant root colonization. Some 168 variants are indeed unable to develop robust biofilm structures, while others do so as efficiently as the non-domesticated NCIB 3610 strain. In all cases studied, the addition of glucose to the medium dramatically improved biofilm development of the laboratory strains. Furthermore, the expression of biofilm matrix component operons, epsA-O and tapA-sipW-tasA, was monitored during colony biofilm formation. We found a lack of direct correlation between the expression of these genes and the complexity of wrinkles in colony biofilms. However, the presence of a single mutation in the exopolysaccharide-related gene epsC correlates with the ability of the stocks tested to form architecturally complex colonies and pellicles, and to colonize plant roots.
Topics: Bacillus subtilis; Bacterial Proteins; Biofilms; Culture Media; Gene Expression Regulation, Bacterial; Operon
PubMed: 27655338
DOI: 10.1099/mic.0.000371 -
Current Opinion in Microbiology Dec 2007Initial attempts to use colony morphogenesis as a tool to investigate bacterial multicellularity were limited by the fact that laboratory strains often have lost many of... (Review)
Review
Initial attempts to use colony morphogenesis as a tool to investigate bacterial multicellularity were limited by the fact that laboratory strains often have lost many of their developmental properties. Recent advances in elucidating the molecular mechanisms underlying colony morphogenesis have been made possible through the use of undomesticated strains. In particular, Bacillus subtilis has proven to be a remarkable model system to study colony morphogenesis because of its well-characterized developmental features. Genetic screens that analyze mutants defective in colony morphology have led to the discovery of an intricate regulatory network that controls the production of an extracellular matrix. This matrix is essential for the development of complex colony architecture characterized by aerial projections that serve as preferential sites for sporulation. While much progress has been made, the challenge for future studies will be to determine the underlying mechanisms that regulate development such that differentiation occurs in a spatially and temporally organized manner.
Topics: Bacillus subtilis; Bacterial Proteins; Gene Expression Regulation, Bacterial; Morphogenesis; Mutation
PubMed: 17977783
DOI: 10.1016/j.mib.2007.09.006