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New perspectives for mechanisms, ingredients, and their preparation for promoting the formation of beneficial bacterial biofilm. JOURNAL OF FOOD MEASUREMENT AND CHARACTERIZATION 2023. [DOI: 10.1007/s11694-022-01777-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Ventroux M, Noirot-Gros MF. Prophage-encoded small protein YqaH counteracts the activities of the replication initiator DnaA in Bacillus subtilis. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 36748575 DOI: 10.1099/mic.0.001268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Bacterial genomes harbour cryptic prophages that are mostly transcriptionally silent with many unannotated genes. Still, cryptic prophages may contribute to their host fitness and phenotypes. In Bacillus subtilis, the yqaF-yqaN operon belongs to the prophage element skin, and is tightly repressed by the Xre-like repressor SknR. This operon contains several small ORFs (smORFs) potentially encoding small-sized proteins. The smORF-encoded peptide YqaH was previously reported to bind to the replication initiator DnaA. Here, using a yeast two-hybrid assay, we found that YqaH binds to the DNA binding domain IV of DnaA and interacts with Spo0A, a master regulator of sporulation. We isolated single amino acid substitutions in YqaH that abolished the interaction with DnaA but not with Spo0A. Then, using a plasmid-based inducible system to overexpress yqaH WT and mutant derivatives, we studied in B. subtilis the phenotypes associated with the specific loss-of-interaction with DnaA (DnaA_LOI). We found that expression of yqaH carrying DnaA_LOI mutations abolished the deleterious effects of yqaH WT expression on chromosome segregation, replication initiation and DnaA-regulated transcription. When YqaH was induced after vegetative growth, DnaA_LOI mutations abolished the drastic effects of YqaH WT on sporulation and biofilm formation. Thus, YqaH inhibits replication, sporulation and biofilm formation mainly by antagonizing DnaA in a manner that is independent of the cell cycle checkpoint Sda.
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Affiliation(s)
- Magali Ventroux
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France
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Ran X, Zhu Z, Long H, Tian Q, You L, Wu X, Liu Q, Huang S, Li S, Niu X, Wang J. Manganese Stress Adaptation Mechanisms of Bacillus safensis Strain ST7 From Mine Soil. Front Microbiol 2021; 12:758889. [PMID: 34899642 PMCID: PMC8656422 DOI: 10.3389/fmicb.2021.758889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Accepted: 10/21/2021] [Indexed: 11/23/2022] Open
Abstract
The mechanism of bacterial adaption to manganese-polluted environments was explored using 50 manganese-tolerant strains of bacteria isolated from soil of the largest manganese mine in China. Efficiency of manganese removal by the isolated strains was investigated using atomic absorption spectrophotometry. Bacillus safensis strain ST7 was the most effective manganese-oxidizing bacteria among the tested isolates, achieving up to 82% removal at a Mn(II) concentration of 2,200 mg/L. Bacteria-mediated manganese oxide precipitates and high motility were observed, and the growth of strain ST7 was inhibited while its biofilm formation was promoted by the presence of Mn(II). In addition, strain ST7 could grow in the presence of high concentrations of Al(III), Cr(VI), and Fe(III). Genome-wide analysis of the gene expression profile of strain ST7 using the RNA-seq method revealed that 2,580 genes were differently expressed under Mn(II) exposure, and there were more downregulated genes (n = 2,021) than upregulated genes (n = 559) induced by Mn stress. KAAS analysis indicated that these differently expressed genes were mainly enriched in material metabolisms, cellular processes, organism systems, and genetic and environmental information processing pathways. A total of twenty-six genes from the transcriptome of strain ST7 were involved in lignocellulosic degradation. Furthermore, after 15 genes were knocked out by homologous recombination technology, it was observed that the transporters, multicopper oxidase, and proteins involved in sporulation and flagellogenesis contributed to the removal of Mn(II) in strain ST7. In summary, B. safensis ST7 adapted to Mn exposure by changing its metabolism, upregulating cation transporters, inhibiting sporulation and flagellogenesis, and activating an alternative stress-related sigB pathway. This bacterial strain could potentially be used to restore soil polluted by multiple heavy metals and is a candidate to support the consolidated bioprocessing community.
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Affiliation(s)
- Xueqin Ran
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Animal Science/Institute of Agro-Bioengineering, Guizhou University, Guiyang, China
| | - Zhongmei Zhu
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Animal Science/Institute of Agro-Bioengineering, Guizhou University, Guiyang, China
| | - Hong Long
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Animal Science/Institute of Agro-Bioengineering, Guizhou University, Guiyang, China
| | - Qun Tian
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Animal Science/Institute of Agro-Bioengineering, Guizhou University, Guiyang, China
| | - Longjiang You
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Animal Science/Institute of Agro-Bioengineering, Guizhou University, Guiyang, China
| | - Xingdiao Wu
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Animal Science/Institute of Agro-Bioengineering, Guizhou University, Guiyang, China
| | - Qin Liu
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Animal Science/Institute of Agro-Bioengineering, Guizhou University, Guiyang, China
| | - Shihui Huang
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Animal Science/Institute of Agro-Bioengineering, Guizhou University, Guiyang, China
| | - Sheng Li
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Animal Science/Institute of Agro-Bioengineering, Guizhou University, Guiyang, China
| | - Xi Niu
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Animal Science/Institute of Agro-Bioengineering, Guizhou University, Guiyang, China
| | - Jiafu Wang
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Animal Science/Institute of Agro-Bioengineering, Guizhou University, Guiyang, China
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Menikpurage IP, Woo K, Mera PE. Transcriptional Activity of the Bacterial Replication Initiator DnaA. Front Microbiol 2021; 12:662317. [PMID: 34140937 PMCID: PMC8203912 DOI: 10.3389/fmicb.2021.662317] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/19/2021] [Indexed: 11/13/2022] Open
Abstract
In bacteria, DnaA is the most conserved DNA replication initiator protein. DnaA is a DNA binding protein that is part of the AAA+ ATPase family. In addition to initiating chromosome replication, DnaA can also function as a transcription factor either as an activator or repressor. The first gene identified to be regulated by DnaA at the transcriptional levels was dnaA. DnaA has been shown to regulate genes involved in a variety of cellular events including those that trigger sporulation, DNA repair, and cell cycle regulation. DnaA's dual functions (replication initiator and transcription factor) is a potential mechanism for DnaA to temporally coordinate diverse cellular events with the onset of chromosome replication. This strategy of using chromosome replication initiator proteins as regulators of gene expression has also been observed in archaea and eukaryotes. In this mini review, we focus on our current understanding of DnaA's transcriptional activity in various bacterial species.
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Affiliation(s)
- Inoka P Menikpurage
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Kristin Woo
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Paola E Mera
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
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Noirot-Gros MF, Shinde SV, Akins C, Johnson JL, Zerbs S, Wilton R, Kemner KM, Noirot P, Babnigg G. Functional Imaging of Microbial Interactions With Tree Roots Using a Microfluidics Setup. FRONTIERS IN PLANT SCIENCE 2020; 11:408. [PMID: 32351525 PMCID: PMC7174594 DOI: 10.3389/fpls.2020.00408] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 03/20/2020] [Indexed: 05/20/2023]
Abstract
Coupling microfluidics with microscopy has emerged as a powerful approach to study at cellular resolution the dynamics in plant physiology and root-microbe interactions (RMIs). Most devices have been designed to study the model plant Arabidopsis thaliana at higher throughput than conventional methods. However, there is a need for microfluidic devices which enable in vivo studies of root development and RMIs in woody plants. Here, we developed the RMI-chip, a simple microfluidic setup in which Populus tremuloides (aspen tree) seedlings can grow for over a month, allowing continuous microscopic observation of interactions between live roots and rhizobacteria. We find that the colonization of growing aspen roots by Pseudomonas fluorescens in the RMI-chip involves dynamic biofilm formation and dispersal, in keeping with previous observations in a different experimental set-up. Also, we find that whole-cell biosensors based on the rhizobacterium Bacillus subtilis can be used to monitor compositional changes in the rhizosphere but that the application of these biosensors is limited by their efficiency at colonizing aspen roots and persisting. These results indicate that functional imaging of dynamic root-bacteria interactions in the RMI-chip requires careful matching between the host plant and the bacterial root colonizer.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Gyorgy Babnigg
- Biosciences Division, Argonne National Laboratory, Lemont, IL, United States
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Huang Z, Wu L, Li X, Ma L, Borriss R, Gao X. Zn(II) suppresses biofilm formation in Bacillus amyloliquefaciens by inactivation of the Mn(II) uptake. Environ Microbiol 2019; 22:1547-1558. [PMID: 31715659 DOI: 10.1111/1462-2920.14859] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 11/08/2019] [Accepted: 11/10/2019] [Indexed: 11/29/2022]
Abstract
Biofilms are architecturally complex communities of microbial cells held together by a self-produced extracellular matrix. Considerable research has focused on the environmental signals that trigger or inhibit biofilm formation by affecting cellular signalling pathways; however, response to soil cues in plant-associated Bacillus has remained largely unaddressed. Therefore, we aimed to investigate the effect of Zn(II) ions in biofilm formation of Bacillus amyloliquefaciens FZB42. We demonstrated that the biofilm formation of B. amyloliquefaciens FZB42 was abolished by Zn(II) at non-deleterious concentrations. Moreover, Zn(II) blocked matrix exopolysaccharide and TasA accumulations. Furthermore, the presence of Zn(II) suppressed expression of the response regulator Spo0F but not of sensor histidine kinases KinA-D. Suppression of phosphorelay by excess Zn interferes with sinI induction under biofilm-inducing conditions, leading to repression of transcription of operons epsA-O and tapA-sigW-tasA. Addition of Zn(II) decreased the intracellular Mn(II) level by competing for binding to the solute-binding protein MntA during Mn(II) uptake. These results suggest that the metal ion Zn(II) has a negative effect on biofilm formation in the plant growth promoting and biocontrol bacterium B. amyloliquefaciens FZB42.
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Affiliation(s)
- Ziyang Huang
- College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Monitoring and Management of Crop Disease and Pest Insects, Ministry of Education, Nanjing, 210095, China
| | - Liming Wu
- College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Monitoring and Management of Crop Disease and Pest Insects, Ministry of Education, Nanjing, 210095, China
| | - Xi Li
- College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Monitoring and Management of Crop Disease and Pest Insects, Ministry of Education, Nanjing, 210095, China
| | - Liumin Ma
- College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Monitoring and Management of Crop Disease and Pest Insects, Ministry of Education, Nanjing, 210095, China
| | - Rainer Borriss
- Nord Reet UG, Greifswald, Germany.,Fachgebiet Phytomedizin, Institut für Agrar- und Gartenbauwissenschaften, Humboldt Universität, Berlin, Germany
| | - Xuewen Gao
- College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Monitoring and Management of Crop Disease and Pest Insects, Ministry of Education, Nanjing, 210095, China
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García García T, Ventroux M, Derouiche A, Bidnenko V, Correia Santos S, Henry C, Mijakovic I, Noirot-Gros MF, Poncet S. Phosphorylation of the Bacillus subtilis Replication Controller YabA Plays a Role in Regulation of Sporulation and Biofilm Formation. Front Microbiol 2018; 9:486. [PMID: 29619013 PMCID: PMC5871692 DOI: 10.3389/fmicb.2018.00486] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/01/2018] [Indexed: 11/13/2022] Open
Abstract
Bacillus subtilis cells can adopt different life-styles in response to various environmental cues, including planktonic cells during vegetative growth, sessile cells during biofilm formation and sporulation. While switching life-styles, bacteria must coordinate the progression of their cell cycle with their physiological status. Our current understanding of the regulatory pathways controlling the decision-making processes and triggering developmental switches highlights a key role of protein phosphorylation. The regulatory mechanisms that integrate the bacterial chromosome replication status with sporulation involve checkpoint proteins that target the replication initiator DnaA or the kinase phosphorelay controlling the master regulator Spo0A. B. subtilis YabA is known to interact with DnaA to prevent over-initiation of replication during vegetative growth. Here, we report that YabA is phosphorylated by YabT, a Ser/Thr kinase expressed during sporulation and biofilm formation. The phosphorylation of YabA has no effect on replication initiation control but hyper-phosphorylation of YabA leads to an increase in sporulation efficiency and a strong inhibition of biofilm formation. We also provide evidence that YabA phosphorylation affects the level of Spo0A-P in cells. These results indicate that YabA is a multifunctional protein with a dual role in regulating replication initiation and life-style switching, thereby providing a potential mechanism for cross-talk and coordination of cellular processes during adaptation to environmental change.
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Affiliation(s)
| | - Magali Ventroux
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | | | - Vladimir Bidnenko
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Sara Correia Santos
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Céline Henry
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Ivan Mijakovic
- Systems and Synthetic Biology, Chalmers University of Technology, Göteborg, Sweden
| | | | - Sandrine Poncet
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
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Washington TA, Smith JL, Grossman AD. Genetic networks controlled by the bacterial replication initiator and transcription factor DnaA in Bacillus subtilis. Mol Microbiol 2017; 106:109-128. [PMID: 28752667 DOI: 10.1111/mmi.13755] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/21/2017] [Indexed: 12/21/2022]
Abstract
DnaA is the widely conserved bacterial AAA+ ATPase that functions as both the replication initiator and a transcription factor. In many organisms, DnaA controls expression of its own gene and likely several others during growth and in response to replication stress. To evaluate the effects of DnaA on gene expression, separate from its role in replication initiation, we analyzed changes in mRNA levels in Bacillus subtilis cells with and without dnaA, using engineered strains in which dnaA is not essential. We found that dnaA was required for many of the changes in gene expression in response to replication stress. We also found that dnaA indirectly affected expression of several regulons during growth, including those controlled by the transcription factors Spo0A, AbrB, PhoP, SinR, RemA, Rok and YvrH. These effects were largely mediated by the effects of DnaA on expression of sda. DnaA activates transcription of sda, and Sda inhibits histidine protein kinases required for activation of the transcription factor Spo0A. We also found that loss of dnaA caused a decrease in the development of genetic competence. Together, our results indicate that DnaA plays an important role in modulating cell physiology, separate from its role in replication initiation.
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Affiliation(s)
- Tracy A Washington
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Janet L Smith
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Alan D Grossman
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Pirated Siderophores Promote Sporulation in Bacillus subtilis. Appl Environ Microbiol 2017; 83:AEM.03293-16. [PMID: 28283524 PMCID: PMC5411514 DOI: 10.1128/aem.03293-16] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 03/07/2017] [Indexed: 11/20/2022] Open
Abstract
In microbial communities, bacteria chemically and physically interact with one another. Some of these interactions are mediated by secreted specialized metabolites that act as either intraspecies or interspecies signals to alter gene expression and to change cell physiology. Bacillus subtilis is a well-characterized soil microbe that can differentiate into multiple cell types, including metabolically dormant endospores. We were interested in identifying microbial interactions that affected sporulation in B. subtilis. Using a fluorescent transcriptional reporter, we observed that coculturing B. subtilis with Escherichia coli promoted sporulation gene expression via a secreted metabolite. To identify the active compound, we screened the E. coli Keio Collection and identified the sporulation-accelerating cue as the siderophore enterobactin. B. subtilis has multiple iron acquisition systems that are used to take up the B. subtilis-produced siderophore bacillibactin, as well as to pirate exogenous siderophores such as enterobactin. While B. subtilis uses a single substrate binding protein (FeuA) to take up both bacillibactin and enterobactin, we discovered that it requires two distinct genes to sporulate in response to these siderophores (the esterase gene besA for bacillibactin and a putative esterase gene, ybbA, for enterobactin). In addition, we found that siderophores from a variety of other microbial species also promote sporulation in B. subtilis. Our results thus demonstrate that siderophores can act not only as bacterial iron acquisition systems but also as interspecies cues that alter cellular development and accelerate sporulation in B. subtilis. IMPORTANCE While much is known about the genetic regulation of Bacillus subtilis sporulation, little is understood about how other bacteria influence this process. This work describes an interaction between Escherichia coli and B. subtilis that accelerates sporulation in B. subtilis. The interaction is mediated by the E. coli siderophore enterobactin; we show that other species' siderophores also promote sporulation gene expression in B. subtilis. These results suggest that siderophores not only may supply bacteria with the mineral nutrient iron but also may play a role in bacterial interspecies signaling, providing a cue for sporulation. Siderophores are produced by many bacterial species and thus potentially play important roles in altering bacterial cell physiology in diverse environments.
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Seid CA, Smith JL, Grossman AD. Genetic and biochemical interactions between the bacterial replication initiator DnaA and the nucleoid-associated protein Rok in Bacillus subtilis. Mol Microbiol 2017; 103:798-817. [PMID: 27902860 DOI: 10.1111/mmi.13590] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/25/2016] [Indexed: 12/16/2022]
Abstract
We identified interactions between the conserved bacterial replication initiator and transcription factor DnaA and the nucleoid-associated protein Rok of Bacillus subtilis. DnaA binds directly to clusters of DnaA boxes at the origin of replication and elsewhere, including the promoters of several DnaA-regulated genes. Rok, an analog of H-NS from gamma-proteobacteria that affects chromosome architecture and of Lsr2 from Mycobacteria, binds A+T-rich sequences throughout the genome and represses expression of many genes. Using crosslinking and immunoprecipitation followed by deep sequencing (ChIP-seq), we found that DnaA was associated with eight previously identified regions containing clusters of DnaA boxes, plus 36 additional regions that were also bound by Rok. Association of DnaA with these additional regions appeared to be indirect as it was dependent on Rok and independent of the DNA-binding domain of DnaA. Gene expression and mutant analyses support a model in which DnaA and Rok cooperate to repress transcription of yxaJ, the yybNM operon and the sunA-bdbB operon. Our results indicate that DnaA modulates the activity of Rok. We postulate that this interaction might affect nucleoid architecture. Furthermore, DnaA might interact similarly with Rok analogues in other organisms.
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Affiliation(s)
- Charlotte A Seid
- Department of Biology, Massachusetts Institute of Technology, Building 68-530, Cambridge, MA, 02139, USA
| | - Janet L Smith
- Department of Biology, Massachusetts Institute of Technology, Building 68-530, Cambridge, MA, 02139, USA
| | - Alan D Grossman
- Department of Biology, Massachusetts Institute of Technology, Building 68-530, Cambridge, MA, 02139, USA
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Yan F, Yu Y, Wang L, Luo Y, Guo JH, Chai Y. The comER Gene Plays an Important Role in Biofilm Formation and Sporulation in both Bacillus subtilis and Bacillus cereus. Front Microbiol 2016; 7:1025. [PMID: 27446060 PMCID: PMC4923064 DOI: 10.3389/fmicb.2016.01025] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 06/16/2016] [Indexed: 02/02/2023] Open
Abstract
Bacteria adopt alternative cell fates during development. In Bacillus subtilis, the transition from planktonic growth to biofilm formation and sporulation is controlled by a complex regulatory circuit, in which the most important event is activation of Spo0A, a transcription factor and a master regulator for genes involved in both biofilm formation and sporulation. In B. cereus, the regulatory pathway controlling biofilm formation and cell differentiation is much less clear. In this study, we show that a novel gene, comER, plays a significant role in biofilm formation as well as sporulation in both B. subtilis and B. cereus. Mutations in the comER gene result in defects in biofilm formation and a delay in spore formation in the two Bacillus species. Our evidence supports the idea that comER may be part of the regulatory circuit that controls Spo0A activation. comER likely acts upstream of sda, a gene encoding a small checkpoint protein for both sporulation and biofilm formation, by blocking the phosphor-relay and thereby Spo0A activation. In summary, our studies outlined a conserved, positive role for comER, a gene whose function was previously uncharacterized, in the regulation of biofilm formation and sporulation in the two Bacillus species.
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Affiliation(s)
- Fang Yan
- Department of Plant Pathology, Nanjing Agricultural University, NanjingChina; Department of Biology, Northeastern University, Boston, MAUSA
| | - Yiyang Yu
- Department of Plant Pathology, Nanjing Agricultural University, NanjingChina; Department of Biology, Northeastern University, Boston, MAUSA
| | - Luyao Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing China
| | - Yuming Luo
- Jiangsu Collaborative Center of Regional Modern Agriculture and Environmental Protection, Nanjing China
| | - Jian-Hua Guo
- Department of Plant Pathology, Nanjing Agricultural University, NanjingChina; Jiangsu Collaborative Center of Regional Modern Agriculture and Environmental Protection, NanjingChina; Engineering Center of Bioresource Pesticide in Jiangsu Province, Key Laboratory of Integrated Management of Crop Diseases and Pests, NanjingChina
| | - Yunrong Chai
- Department of Biology, Northeastern University, Boston, MA USA
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Mhatre E, Troszok A, Gallegos-Monterrosa R, Lindstädt S, Hölscher T, Kuipers OP, Kovács ÁT. The impact of manganese on biofilm development of Bacillus subtilis. MICROBIOLOGY-SGM 2016; 162:1468-1478. [PMID: 27267987 DOI: 10.1099/mic.0.000320] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Bacterial biofilms are dynamic and structurally complex communities, involving cell-to-cell interactions. In recent years, various environmental signals that induce the complex biofilm development of the Gram-positive bacterium Bacillus subtilis have been identified. These signalling molecules are often media components or molecules produced by the cells themselves, as well as those of other interacting species. The responses can also be due to depletion of certain molecules in the vicinity of the cells. Extracellular manganese (Mn2+) is essential for proper biofilm development of B. subtilis. Mn2+ is also a component of practically all laboratory biofilm-promoting media used for B. subtilis. Comparison of complex colony biofilms in the presence or absence of supplemented Mn2+ using microarray analyses revealed that genes involved in biofilm formation are indeed downregulated in the absence of Mn2+. In addition, Mn2+ also affects the transcription of several other genes involved in distinct differentiation pathways of various cellular processes. The effects of Mn2+ on other biofilm-related traits like motility, antimicrobial production, stress and sporulation were followed using fluorescent reporter strains. The global transcriptome and morphology studies highlight the importance of Mn2+ during biofilm development and provide an overview on the expressional changes in colony biofilms in B. subtilis.
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Affiliation(s)
- Eisha Mhatre
- Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, Jena, Germany
| | - Agnieszka Troszok
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Ramses Gallegos-Monterrosa
- Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, Jena, Germany
| | - Stefanie Lindstädt
- Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, Jena, Germany
| | - Theresa Hölscher
- Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, Jena, Germany
| | - Oscar P Kuipers
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Ákos T Kovács
- Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, Jena, Germany
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The Bacterial Tyrosine Kinase Activator TkmA Contributes to Biofilm Formation Largely Independently of the Cognate Kinase PtkA in Bacillus subtilis. J Bacteriol 2015; 197:3421-32. [PMID: 26283769 DOI: 10.1128/jb.00438-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 08/12/2015] [Indexed: 01/05/2023] Open
Abstract
UNLABELLED In Bacillus subtilis, biosynthesis of exopolysaccharide (EPS), a key biofilm matrix component, is regulated at the posttranslational level by the bacterial tyrosine kinase (BY-kinase) EpsB. EpsB, in turn, relies on the cognate kinase activator EpsA for activation. A concerted role of a second BY-kinase-kinase activator pair, PtkA and TkmA, respectively in biofilm formation was also indicated in previous studies. However, the exact functions of PtkA and TkmA in biofilm formation remain unclear. In this work, we show that the kinase activator TkmA contributes to biofilm formation largely independently of the cognate kinase, PtkA. We further show that the biofilm defect caused by a ΔtkmA mutation can be rescued by complementation by epsA, suggesting a functional overlap between TkmA and EpsA and providing a possible explanation for the role of TkmA in biofilm formation. We also show that the importance of TkmA in biofilm formation depends largely on medium conditions; the biofilm defect of ΔtkmA is very severe in the biofilm medium LBGM (lysogenic broth [LB] supplemented with 1% [vol/vol] glycerol and 100 μM MnSO4) but marginal in another commonly used biofilm medium, MSgg (5 mM potassium phosphate [pH 7.0], MOPS [100 mM morpholinepropanesulfonic acid] [pH 7.0], 2 mM MgCl2, 700 μM CaCl2, 50 μM MnCl2, 50 μM FeCl3, 1 μM ZnCl2, 2 μM thiamine, 0.5% glycerol, 0.5% glutamic acid, 50 μg/ml tryptophan, 50 μg/ml threonine, and 50 μg/ml phenylalanine). The molecular basis for the medium dependence is likely due to differential expression of tkmA and epsA in the two different media and complex regulation of these genes by both Spo0A and DegU. Our studies provide genetic evidence for possible cross talk between a BY-kinase activator (TkmA) and a noncognate kinase (EpsB) and an example of how environmental conditions may influence such cross talk in regulating biofilm formation in B. subtilis. IMPORTANCE In bacteria, biosynthesis of secreted polysaccharides is often regulated by bacterial tyrosine kinases (BY-kinases). BY-kinases, in turn, rely on cognate kinase activators for activation. In this study, we investigated the role of a BY-kinase activator in biofilm formation in Bacillus subtilis. We present evidence that different BY-kinase activators may functionally overlap each other, as well as an example of how activities of the BY-kinase activators may be highly dependent on environmental conditions. Our study broadens the understanding of the complexity of regulation of the BY-kinases/kinase activators and the influence on bacterial cell physiology.
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Kawai Y, Mercier R, Wu LJ, Domínguez-Cuevas P, Oshima T, Errington J. Cell growth of wall-free L-form bacteria is limited by oxidative damage. Curr Biol 2015; 25:1613-8. [PMID: 26051891 PMCID: PMC4510147 DOI: 10.1016/j.cub.2015.04.031] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 04/09/2015] [Accepted: 04/14/2015] [Indexed: 11/30/2022]
Abstract
The peptidoglycan (PG) cell wall is a defining feature of the bacterial lineage and an important target for antibiotics, such as β-lactams and glycopeptides. Nevertheless, many bacteria are capable of switching into a cell-wall-deficient state, called the “L-form” [1–3]. These variants have been classically identified as antibiotic-resistant forms in association with a wide range of infectious diseases [4]. L-forms become completely independent of the normally essential FtsZ cell division machinery [3, 5]. Instead, L-form proliferation is driven by a simple biophysical process based on an increased ratio of surface area to cell volume synthesis [6, 7]. We recently showed that only two genetic changes are needed for the L-form transition in Bacillus subtilis [7]. Class 1 mutations work to generate excess membrane synthesis [7]. Until now, the function of the class 2 mutations was unclear. We now show that these mutations work by counteracting an increase in the cellular levels of reactive oxygen species (ROS) originating from the electron transport pathway, which occurs in wall-deficient cells. Consistent with this, addition of a ROS scavenger or anaerobic culture conditions also worked to promote L-form growth without the class 2 mutations in both Gram-positive B. subtilis and Gram-negative Escherichia coli. Our results suggest that physiological compensation for the metabolic imbalance that occurs when cell wall synthesis is blocked is crucial for L-form proliferation in a wide range of bacteria and also provide new insights into the mode of action of antibiotics that target the bacterial cell wall. The cellular levels of ROS are increased when cell wall synthesis is blocked Oxidative damage is a serious impediment to growth of wall-deficient L-forms Reduction of ROS levels promotes L-form growth L-forms provide new insights into the mode of action of cell wall antibiotics
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Affiliation(s)
- Yoshikazu Kawai
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK.
| | - Romain Mercier
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK
| | - Ling Juan Wu
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK
| | | | - Taku Oshima
- Genomics of Bacterial Cell Functions, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0192, Japan
| | - Jeff Errington
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK.
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Smith JL, Grossman AD. In Vitro Whole Genome DNA Binding Analysis of the Bacterial Replication Initiator and Transcription Factor DnaA. PLoS Genet 2015; 11:e1005258. [PMID: 26020636 PMCID: PMC4447404 DOI: 10.1371/journal.pgen.1005258] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 05/01/2015] [Indexed: 11/18/2022] Open
Abstract
DnaA, the replication initiation protein in bacteria, is an AAA+ ATPase that binds and hydrolyzes ATP and exists in a heterogeneous population of ATP-DnaA and ADP-DnaA. DnaA binds cooperatively to the origin of replication and several other chromosomal regions, and functions as a transcription factor at some of these regions. We determined the binding properties of Bacillus subtilis DnaA to genomic DNA in vitro at single nucleotide resolution using in vitro DNA affinity purification and deep sequencing (IDAP-Seq). We used these data to identify 269 binding regions, refine the consensus sequence of the DnaA binding site, and compare the relative affinity of binding regions for ATP-DnaA and ADP-DnaA. Most sites had a slightly higher affinity for ATP-DnaA than ADP-DnaA, but a few had a strong preference for binding ATP-DnaA. Of the 269 sites, only the eight strongest binding ones have been observed to bind DnaA in vivo, suggesting that other cellular factors or the amount of available DnaA in vivo restricts DnaA binding to these additional sites. Conversely, we found several chromosomal regions that were bound by DnaA in vivo but not in vitro, and that the nucleoid-associated protein Rok was required for binding in vivo. Our in vitro characterization of the inherent ability of DnaA to bind the genome at single nucleotide resolution provides a backdrop for interpreting data on in vivo binding and regulation of DnaA, and is an approach that should be adaptable to many other DNA binding proteins.
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Affiliation(s)
- Janet L Smith
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Alan D Grossman
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
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Hoover SE, Perez AJ, Tsui HCT, Sinha D, Smiley DL, DiMarchi RD, Winkler ME, Lazazzera BA. A new quorum-sensing system (TprA/PhrA) for Streptococcus pneumoniae D39 that regulates a lantibiotic biosynthesis gene cluster. Mol Microbiol 2015; 97:229-43. [PMID: 25869931 DOI: 10.1111/mmi.13029] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/12/2015] [Indexed: 12/20/2022]
Abstract
The Phr peptides of the Bacillus species mediate quorum sensing, but their identification and function in other species of bacteria have not been determined. We have identified a Phr peptide quorum-sensing system (TprA/PhrA) that controls the expression of a lantibiotic gene cluster in the Gram-positive human pathogen, Streptococcus pneumoniae. Lantibiotics are highly modified peptides that are part of the bacteriocin family of antimicrobial peptides. We have characterized the basic mechanism for a Phr-peptide signaling system in S. pneumoniae and found that it induces the expression of the lantibiotic genes when pneumococcal cells are at high density in the presence of galactose, a main sugar of the human nasopharynx, a highly competitive microbial environment. Activity of the Phr peptide system is not seen when pneumococcal cells are grown with glucose, the preferred carbon source and the most prevalent sugar encountered by S. pneumoniae during invasive disease. Thus, the lantibiotic genes are expressed under the control of both cell density signals via the Phr peptide system and nutritional signals from the carbon source present, suggesting that quorum sensing and the lantibiotic machinery may help pneumococcal cells compete for space and resources during colonization of the nasopharynx.
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Affiliation(s)
- Sharon E Hoover
- Department of Microbiology, Immunology and Molecular Genetics, University of California, 609 Charles E. Young Dr. East, 1602 Molecular Science Building, Los Angeles, California, 90095, USA
| | - Amilcar J Perez
- Department of Microbiology, Immunology and Molecular Genetics, University of California, 609 Charles E. Young Dr. East, 1602 Molecular Science Building, Los Angeles, California, 90095, USA
| | - Ho-Ching T Tsui
- Department of Biology, Indiana University Bloomington, Jordan Hall, 1001 East Third Street, Bloomington, Indiana, 47405, USA
| | - Dhriti Sinha
- Department of Biology, Indiana University Bloomington, Jordan Hall, 1001 East Third Street, Bloomington, Indiana, 47405, USA
| | - David L Smiley
- Department of Chemistry, Indiana University Bloomington, 800 E. Kirkwood Avenue, Bloomington, Indiana, 47405, USA
| | - Richard D DiMarchi
- Department of Chemistry, Indiana University Bloomington, 800 E. Kirkwood Avenue, Bloomington, Indiana, 47405, USA
| | - Malcolm E Winkler
- Department of Biology, Indiana University Bloomington, Jordan Hall, 1001 East Third Street, Bloomington, Indiana, 47405, USA
| | - Beth A Lazazzera
- Department of Microbiology, Immunology and Molecular Genetics, University of California, 609 Charles E. Young Dr. East, 1602 Molecular Science Building, Los Angeles, California, 90095, USA
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Li X, Chen L, Zhu Y, Yu X, Cao J, Wang R, Lv X, He J, Guo A, Huang H, Zheng H, Liu S. Genomic analysis of a Mycobacterium bovis bacillus [corrected] Calmette-Guérin strain isolated from an adult patient with pulmonary tuberculosis.. PLoS One 2015; 10:e0122403. [PMID: 25876043 PMCID: PMC4395146 DOI: 10.1371/journal.pone.0122403] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Accepted: 02/20/2015] [Indexed: 12/04/2022] Open
Abstract
For years, bacillus Calmette-Guérin (BCG) has served as the unique vaccine against tuberculosis and has generally been regarded as safe. However, a clinical strain labeled 3281 that was isolated from a TB patient was identified to be BCG. Via the combination of next-generation sequencing (NGS) and comparative genomic analysis, unique 3281 genetic characteristics were revealed. A region containing the dnaA and dnaN genes that is closely related to the initial chromosome replication was found to repeat three times on the BCG Pasteur-specific tandem duplication region DU1. Due to the minimum number of epitopes in BCG strains, 3281 was inferred to have a high possibility for immune evasion. Additionally, variations in the virulence genes and predictions for potential virulence factors were analyzed. Overall, we report a pathogen that has never previously been thought to be pathogenic and initial insights that are focused on the genetic characteristics of virulent BCG.
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Affiliation(s)
- Xuming Li
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agriculture, Harbin 150001, China
- Stake Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Liping Chen
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agriculture, Harbin 150001, China
| | - Yongqiang Zhu
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai 201203, China
| | - Xia Yu
- National Clinical Laboratory on Tuberculosis, Beijing Key Laboratory on Drug-resistant Tuberculosis Research, Beijing Tuberculosis and Thoracic Tumor Institute, Beijing Chest Hospital, Capital Medical University, Beijing101149, China
| | - Jun Cao
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agriculture, Harbin 150001, China
| | - Rui Wang
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai 201203, China
| | - Xinyan Lv
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai 201203, China
| | - Jin He
- Stake Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China
| | - Aizhen Guo
- Stake Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China
- * E-mail: (HH); (AG); (HZ); (SL)
| | - Hairong Huang
- National Clinical Laboratory on Tuberculosis, Beijing Key Laboratory on Drug-resistant Tuberculosis Research, Beijing Tuberculosis and Thoracic Tumor Institute, Beijing Chest Hospital, Capital Medical University, Beijing101149, China
- * E-mail: (HH); (AG); (HZ); (SL)
| | - Huajun Zheng
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai 201203, China
- Laboratory of Medical Foods, Shanghai Institute of Planned Parenthood Research, 2140 Xie-Tu Road, Shanghai 200032, China
- * E-mail: (HH); (AG); (HZ); (SL)
| | - Siguo Liu
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agriculture, Harbin 150001, China
- * E-mail: (HH); (AG); (HZ); (SL)
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Role of Bacillus subtilis error prevention oxidized guanine system in counteracting hexavalent chromium-promoted oxidative DNA damage. Appl Environ Microbiol 2014; 80:5493-502. [PMID: 24973075 DOI: 10.1128/aem.01665-14] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chromium pollution is potentially detrimental to bacterial soil communities, compromising carbon and nitrogen cycles that are essential for life on earth. It has been proposed that intracellular reduction of hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] may cause bacterial death by a mechanism that involves reactive oxygen species (ROS)-induced DNA damage; the molecular basis of the phenomenon was investigated in this work. Here, we report that Bacillus subtilis cells lacking a functional error prevention oxidized guanine (GO) system were significantly more sensitive to Cr(VI) treatment than cells of the wild-type (WT) strain, suggesting that oxidative damage to DNA is involved in the deleterious effects of the oxyanion. In agreement with this suggestion, Cr(VI) dramatically increased the ROS concentration and induced mutagenesis in a GO-deficient B. subtilis strain. Alkaline gel electrophoresis (AGE) analysis of chromosomal DNA of WT and ΔGO mutant strains subjected to Cr(VI) treatment revealed that the DNA of the ΔGO strain was more susceptible to DNA glycosylase Fpg attack, suggesting that chromium genotoxicity is associated with 7,8-dihydro-8-oxodeoxyguanosine (8-oxo-G) lesions. In support of this notion, specific monoclonal antibodies detected the accumulation of 8-oxo-G lesions in the chromosomes of B. subtilis cells subjected to Cr(VI) treatment. We conclude that Cr(VI) promotes mutagenesis and cell death in B. subtilis by a mechanism that involves radical oxygen attack of DNA, generating 8-oxo-G, and that such effects are counteracted by the prevention and repair GO system.
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Mhatre E, Monterrosa RG, Kovács AT. From environmental signals to regulators: modulation of biofilm development in Gram-positive bacteria. J Basic Microbiol 2014; 54:616-32. [PMID: 24771632 DOI: 10.1002/jobm.201400175] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 03/30/2014] [Indexed: 12/22/2022]
Abstract
Bacterial lifestyle is influenced by environmental signals, and many differentiation processes in bacteria are governed by the threshold concentrations of molecules present in their niche. Biofilm is one such example where bacteria in their sessile state adapt to a lifestyle that causes several adaptive alterations in the population. Here, a brief overview is given on a variety of environmental signals that bias biofilm development in Gram-positive bacteria, including nutrient conditions, self- and heterologously produced substances, like quorum sensing and host produced molecules. The Gram-positive model organism, Bacillus subtilis is a superb example to illustrate how distinct signals activate sensor proteins that integrate the environmental signals towards global regulators related to biofilm formation. The role of reduced oxygen level, polyketides, antimicrobials, plant secreted carbohydrates, plant cell derived polymers, glycerol, and osmotic conditions are discussed during the transcriptional activation of biofilm related genes in B. subtilis.
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Affiliation(s)
- Eisha Mhatre
- Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, Jena, Germany
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20
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Abstract
Fitness cost is the measure of the metabolic burden of unneeded gene expression. It is defined as the lag in bacterial cells growth harboring unneeded genes relative to unburdened cells. Separate cells can concurrently adapt to the burden, demonstrating a decrease in or even a disappearance of the lag. The precise mechanisms of this adaptation are not clearly understood. One possibility is that an increased amount of free ribosomes "absorb" the unnecessary burden. In this work, the mechanism by which an increased concentration of ribosomes could result in faster growth and mask the unneeded gene expression burden is discussed. The initiation time of chromosome replication by the initiator protein DnaA, for which the accumulation speed depends on the ribosomes amount, is taken into account.
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Affiliation(s)
- Andrey Shuvaev
- Institute of Engineering Physics and Radio Electronics, Siberian Federal University, 79, Svobodny Prospect, Krasnoyarsk, 660041, Russia,
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21
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A combination of glycerol and manganese promotes biofilm formation in Bacillus subtilis via histidine kinase KinD signaling. J Bacteriol 2013; 195:2747-54. [PMID: 23564171 DOI: 10.1128/jb.00028-13] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The spore-forming bacterium Bacillus subtilis forms matrix-enclosed biofilms in response to environmental cues that to date remain poorly defined. Biofilm formation depends on the synthesis of an extracellular matrix, which is indirectly regulated by the transcriptional regulator Spo0A. The activity of Spo0A depends on its phosphorylation state. The level of phosphorylated Spo0A (Spo0A~P) is controlled by a network of kinases and phosphatases, which respond to environmental and physiological signals. In spite of significant progress in understanding biofilm development, the fundamental question of how cells sense the environmental cues that trigger biofilm formation has largely remained unaddressed. Here, we report that biofilm formation of B. subtilis in LB medium is triggered by a combination of glycerol and manganese (GM). Moreover, LB medium with GM significantly stimulates biofilm-associated sporulation and production of an undefined brown pigment. We further show that transcription of the major operons responsible for matrix production and biofilm formation is dramatically enhanced in response to GM. We also establish that KinD is a principal histidine kinase responsible for sensing the presence of GM exclusively by its extracellular CACHE domain. Finally, we show that GM has a similar biofilm-promoting effect in two related Bacillus species, B. licheniformis and B. cereus, indicating that the biofilm-promoting effect of GM is conserved in Bacillus species.
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Rajarajan N, Ward AC, Burgess JG, Glassey J. Use of physiological information and process optimisation enhances production of extracellular nuclease by a marine strain of Bacillus licheniformis. BIORESOURCE TECHNOLOGY 2013; 130:552-558. [PMID: 23334010 DOI: 10.1016/j.biortech.2012.12.064] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 12/07/2012] [Accepted: 12/09/2012] [Indexed: 06/01/2023]
Abstract
The extracellular nuclease, NucB, from Bacillus licheniformis, can digest extracellular DNA in biofilms, causing biofilm dispersal, and may therefore be used commercially to remove biofilms. However, producing quantities of this secreted peptide is difficult and our aim was therefore to improve its laboratory scale production. This study builds on our understanding of B. licheniformis physiology to enhance NucB production. The addition of manganese, which triggers sporulation and enhances NucB expression, lead to a 5-fold increase in NucB production. Optimisation via Placket-Burman design of experiments identified 3 significant medium components and a subsequent Central Composite Design, to determine the optimum levels of these components, resulted in a 10-fold increase to 471U/ml. The optimal phosphate concentration was less than 0.3mM as this is known to inhibit nuclease production. The use of physiologically relevant information combined with optimisation represents a promising approach to increased enzyme production, which may also be widely applicable.
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Abstract
The growing prevalence of antibiotic-resistant infections underscores the need to discover new antibiotics and to use them with maximum effectiveness. In response to these needs, we describe a screening protocol for the discovery of autolysis-inducing agents that uses two Bacillus subtilis reporter strains, SH-536 and BAU-102. To screen chemical libraries, autolysis-inducing agents were first identified with a BAU-102-based screen and then subdivided with SH-536 into two major groups: those that induce autolysis by their direct action on the cell membrane and those that induce autolysis secondary to inhibition of cell wall synthesis. SH-536 distinguishes between the two groups of autolysis-inducing agents by synthesizing and then releasing β-galactosidase (β-Gal) in late stationary phase at a time that cells have nearly stopped growing and are therefore tolerant of cell wall synthesis inhibitors. Four hits, named compound 2, compound 3, compound 5, and compound 24, obtained previously as inducers of autolysis by screening a 10,080-compound discovery library with BAU-102, were probed with SH-536 and found to release β-Gal, indicating that their mode of action was to permeabilize the B. subtilis cell membrane. The four primary hits inhibited growth in Staphylococcus aureus, Enterococcus faecium, Bacillus subtilis, and Bacillus anthracis, with MICs in the 12.5- to 25-μg/ml (20 to 60 μM) range. The four primary hits were further used to probe B. subtilis, and their action was partially characterized with respect to the dependence of induced autolysis on specific autolysins.
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Fang LC, Li Y, Cheng P, Deng J, Jiang LL, Huang H, Zheng JS, Wei H. Characterization of Rhodopseudomonas palustris strain 2C as a potential probiotic. APMIS 2012; 120:743-9. [PMID: 22882264 DOI: 10.1111/j.1600-0463.2012.02902.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 03/08/2012] [Indexed: 12/20/2022]
Abstract
Photosynthetic bacteria (PSB) are prokaryotes that first appeared on the earth 2 billion years ago. Being rich in nutrients and having unique biological transformational function, PSB have been used as medicinal ingredients and healthcare products. However, there is insufficient information about the probiotic properties of PSB. The aim of this study was to characterize the potential probiotic properties of Rhodopseudomonas palustris strain 2C. The tolerance of strain 2C to low pH, high bile salt and simulated gastrointestinal conditions was determined. The susceptibility of strain 2C to 11 antibiotics was screened. The in vitro antioxidative activity and acute toxicity of strain 2C were performed. The survival duration of strain 2C after it had been repeatedly ingested by Wistar rats was determined. Strain 2C was tolerant to low pH, high bile salt concentration, and simulated gastrointestinal conditions. Strain 2C was only resistant to two of the 11 tested antibiotics (penicillin and ampicillin), and it showed antioxidative activity in vitro. When ingested by rats, strain 2C did not cause any bacteria translocation or tissue damage. The survival duration of strain 2C depending on doses ingested by the rats, 3 days after the termination of intake, it could no longer be enriched from the feces. Taken together, these findings indicate that strain 2C may be a potential probiotic strain.
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Affiliation(s)
- Li C Fang
- Department of Clinical Laboratory Medicine, College of Pharmacy and Laboratory Medicine, Third Military Medical University, Chongqing, China
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Primosomal proteins DnaD and DnaB are recruited to chromosomal regions bound by DnaA in Bacillus subtilis. J Bacteriol 2010; 193:640-8. [PMID: 21097613 DOI: 10.1128/jb.01253-10] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The initiation of DNA replication requires the binding of the initiator protein, DnaA, to specific binding sites in the chromosomal origin of replication, oriC. DnaA also binds to many sites around the chromosome, outside oriC, and acts as a transcription factor at several of these. In low-G+C Gram-positive bacteria, the primosomal proteins DnaD and DnaB, in conjunction with loader ATPase DnaI, load the replicative helicase at oriC, and this depends on DnaA. DnaD and DnaB also are required to load the replicative helicase outside oriC during replication restart, independently of DnaA. Using chromatin immunoprecipitation, we found that DnaD and DnaB, but not the replicative helicase, are associated with many of the chromosomal regions bound by DnaA in Bacillus subtilis. This association was dependent on DnaA, and the order of recruitment was the same as that at oriC, but it was independent of a functional oriC and suggests that DnaD and DnaB do not require open complex formation for the stable association with DNA. These secondary binding regions for DnaA could be serving as a reservoir for excess DnaA, DnaD, and DnaB to help properly regulate replication initiation and perhaps are analogous to the proposed function of the datA locus in Escherichia coli. Alternatively, DnaD and DnaB might modulate the activity of DnaA at the secondary binding regions. All three of these proteins are widely conserved and likely have similar functions in a range of organisms.
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