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Avila Santos AP, de Almeida BLS, Bonidia RP, Stadler PF, Stefanic P, Mandic-Mulec I, Rocha U, Sanches DS, de Carvalho ACPLF. BioDeepfuse: a hybrid deep learning approach with integrated feature extraction techniques for enhanced non-coding RNA classification. RNA Biol 2024; 21:1-12. [PMID: 38528797 DOI: 10.1080/15476286.2024.2329451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/23/2024] [Indexed: 03/27/2024] Open
Abstract
The accurate classification of non-coding RNA (ncRNA) sequences is pivotal for advanced non-coding genome annotation and analysis, a fundamental aspect of genomics that facilitates understanding of ncRNA functions and regulatory mechanisms in various biological processes. While traditional machine learning approaches have been employed for distinguishing ncRNA, these often necessitate extensive feature engineering. Recently, deep learning algorithms have provided advancements in ncRNA classification. This study presents BioDeepFuse, a hybrid deep learning framework integrating convolutional neural networks (CNN) or bidirectional long short-term memory (BiLSTM) networks with handcrafted features for enhanced accuracy. This framework employs a combination of k-mer one-hot, k-mer dictionary, and feature extraction techniques for input representation. Extracted features, when embedded into the deep network, enable optimal utilization of spatial and sequential nuances of ncRNA sequences. Using benchmark datasets and real-world RNA samples from bacterial organisms, we evaluated the performance of BioDeepFuse. Results exhibited high accuracy in ncRNA classification, underscoring the robustness of our tool in addressing complex ncRNA sequence data challenges. The effective melding of CNN or BiLSTM with external features heralds promising directions for future research, particularly in refining ncRNA classifiers and deepening insights into ncRNAs in cellular processes and disease manifestations. In addition to its original application in the context of bacterial organisms, the methodologies and techniques integrated into our framework can potentially render BioDeepFuse effective in various and broader domains.
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Affiliation(s)
- Anderson P Avila Santos
- Institute of Mathematics and Computer Sciences, University of São Paulo, São Carlos, Brazil
- Department of Applied Microbial Ecology, Helmholtz Centre for Environmental Research - UFZ GmbH, Leipzig, Saxony, Germany
| | - Breno L S de Almeida
- Institute of Mathematics and Computer Sciences, University of São Paulo, São Carlos, Brazil
| | - Robson P Bonidia
- Institute of Mathematics and Computer Sciences, University of São Paulo, São Carlos, Brazil
- Department of Computer Science, Federal University of Technology - Paraná, UTFPR, Cornélio Procópio, Brazil
| | - Peter F Stadler
- Department of Computer Science and Interdisciplinary Center of Bioinformatics, University of Leipzig, Leipzig, Saxony, Germany
| | - Polonca Stefanic
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Ines Mandic-Mulec
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Ulisses Rocha
- Department of Applied Microbial Ecology, Helmholtz Centre for Environmental Research - UFZ GmbH, Leipzig, Saxony, Germany
| | - Danilo S Sanches
- Department of Computer Science, Federal University of Technology - Paraná, UTFPR, Cornélio Procópio, Brazil
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Dogsa I, Mandic-Mulec I. Multiscale spatial segregation analysis in digital images of biofilms. Biofilm 2023; 6:100157. [PMID: 37790733 PMCID: PMC10542597 DOI: 10.1016/j.bioflm.2023.100157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 09/15/2023] [Accepted: 09/19/2023] [Indexed: 10/05/2023] Open
Abstract
Quantifying the degree of spatial segregation of two bacterial strains in mixed biofilms is an important topic in microbiology. Spatial segregation is dependent on spatial scale as two strains may appear to be well mixed if observed from a distance, but a closer look can reveal strong separation. Typically, this information is encoded in a digital image that represents the binary system, e.g., a microscopy image of a two species biofilm. To decode spatial segregation information, we have developed quantitative measures for evaluating the degree of the spatial scale-dependent segregation of two bacterial strains in a digital image. The constructed algorithm is based on the new segregation measures and overcomes drawbacks of existing approaches for biofilm segregation analysis. The new approach is implemented in a freely available software and was successfully applied to biofilms of two strains and bacterial suspensions for detection of the different spatial scale-dependent segregation levels.
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Affiliation(s)
- Iztok Dogsa
- Chair of Microbiology, Department of Microbiology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000, Ljubljana, EU, Slovenia
| | - Ines Mandic-Mulec
- Chair of Microbiology, Department of Microbiology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000, Ljubljana, EU, Slovenia
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Danevčič T, Spacapan M, Dragoš A, Kovács ÁT, Mandic-Mulec I. DegQ is an important policing link between quorum sensing and regulated adaptative traits in Bacillus subtilis. Microbiol Spectr 2023; 11:e0090823. [PMID: 37676037 PMCID: PMC10581247 DOI: 10.1128/spectrum.00908-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 07/26/2023] [Indexed: 09/08/2023] Open
Abstract
Quorum sensing (QS) is a widespread bacterial communication system that controls important adaptive traits in a cell density-dependent manner. However, mechanisms by which QS-regulated traits are linked within the cell and mechanisms by which these links affect adaptation are not well understood. In this study, Bacillus subtilis was used as a model bacterium to investigate the link between the ComQXPA QS system, DegQ, surfactin and protease production in planktonic and biofilm cultures. The work tests two alternative hypotheses predicting that hypersensitivity of the QS signal-deficient mutant (comQ::kan) to exogenously added ComX, resulting in increased surfactin production, is linked to an additional genetic locus, or alternatively, to overexpression of the ComX receptor ComP. Results are in agreement with the first hypothesis and show that the P srfAA hypersensitivity of the comQ::kan mutant is linked to a 168 strain-specific mutation in the P degQ region. Hence, the markerless ΔcomQ mutant lacking this mutation is not overresponsive to ComX. Such hyper-responsiveness is specific for the P srfAA and not detected in another ComX-regulated promoter, the P aprE , which is under the positive control by DegQ. Our results suggest that DegQ by exerting differential effect on P srfAA and P aprE acts as a policing mechanism and the intracellular link, which guards the cell from an overinvestment into surfactin production. IMPORTANCE DegQ levels are known to regulate surfactin synthesis and extracellular protease production, and DegQ is under the control of the ComX-dependent QS. DegQ also serves as an important policing link between these QS-regulated processes, preventing overinvestment in these costly processes. This work highlights the importance of DegQ, which acts as the intracellular link between ComX production and the response by regulating extracellular degradative enzyme synthesis and surfactin production.
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Affiliation(s)
- Tjaša Danevčič
- Department of Microbiology, Chair of microbial ecology and physiology, University of Ljubljana, Biotechnical Faculty, Ljubljana, Slovenia
| | - Mihael Spacapan
- Department of Microbiology, Chair of microbial ecology and physiology, University of Ljubljana, Biotechnical Faculty, Ljubljana, Slovenia
| | - Anna Dragoš
- Department of Microbiology, Chair of microbial ecology and physiology, University of Ljubljana, Biotechnical Faculty, Ljubljana, Slovenia
| | - Ákos T. Kovács
- Department of Biotechnology and Biomedicine, Bacterial Interactions and Evolution Group, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Ines Mandic-Mulec
- Department of Microbiology, Chair of microbial ecology and physiology, University of Ljubljana, Biotechnical Faculty, Ljubljana, Slovenia
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Podnar E, Erega A, Danevčič T, Kovačec E, Lories B, Steenackers H, Mandic-Mulec I. Nutrient Availability and Biofilm Polysaccharide Shape the Bacillaene-Dependent Antagonism of Bacillus subtilis against Salmonella Typhimurium. Microbiol Spectr 2022; 10:e0183622. [PMID: 36342318 PMCID: PMC9769773 DOI: 10.1128/spectrum.01836-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 10/18/2022] [Indexed: 11/09/2022] Open
Abstract
Salmonella enterica is one of the most common foodborne pathogens and, due to the spread of antibiotic resistance, new antimicrobial strategies are urgently needed to control it. In this study, we explored the probiotic potential of Bacillus subtilis PS-216 and elucidated the mechanisms that underlie the interactions between this soil isolate and the model pathogenic strain S. Typhimurium SL1344. The results reveal that B. subtilis PS-216 inhibits the growth and biofilm formation of S. Typhimurium through the production of the pks cluster-dependent polyketide bacillaene. The presence of S. Typhimurium enhanced the activity of the PpksC promoter that controls bacillaene production, suggesting that B. subtilis senses and responds to Salmonella. The level of Salmonella inhibition, overall PpksC activity, and PpksC induction by Salmonella were all higher in nutrient-rich conditions than in nutrient-depleted conditions. Although eliminating the extracellular polysaccharide production of B. subtilis via deletion of the epsA-O operon had no significant effect on inhibitory activity against Salmonella in nutrient-rich conditions, this deletion mutant showed an enhanced antagonism against Salmonella in nutrient-depleted conditions, revealing an intricate relationship between exopolysaccharide production, nutrient availability, and bacillaene synthesis. Overall, this work provides evidence on the regulatory role of nutrient availability, sensing of the competitor, and EpsA-O polysaccharide in the social outcome of bacillaene-dependent competition between B. subtilis and S. Typhimurium. IMPORTANCE Probiotic bacteria represent an alternative for controlling foodborne disease caused by Salmonella enterica, which constitutes a serious concern during food production due to its antibiotic resistance and resilience to environmental stress. Bacillus subtilis is gaining popularity as a probiotic, but its behavior in biofilms with pathogens such as Salmonella remains to be elucidated. Here, we show that the antagonism of B. subtilis is mediated by the polyketide bacillaene and that the production of bacillaene is a highly dynamic trait which depends on environmental factors such as nutrient availability and the presence of competitors. Moreover, the production of extracellular polysaccharides by B. subtilis further alters the influence of these factors. Hence, this work highlights the inhibitory effect of B. subtilis, which is condition-dependent, and the importance of evaluating probiotic strains under conditions relevant to the intended use.
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Affiliation(s)
- Eli Podnar
- Department of Microbiology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Andi Erega
- Department of Microbiology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Tjaša Danevčič
- Department of Microbiology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Eva Kovačec
- Department of Microbiology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Bram Lories
- Department of Microbial and Molecular Systems, Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium
| | - Hans Steenackers
- Department of Microbial and Molecular Systems, Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium
| | - Ines Mandic-Mulec
- Department of Microbiology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
- Chair of Microprocess Engineering and Technology (COMPETE), University of Ljubljana, Ljubljana, Slovenia
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Liu Y, Štefanič P, Miao Y, Xue Y, Xun W, Zhang N, Shen Q, Zhang R, Xu Z, Mandic-Mulec I. Housekeeping gene gyrA, a potential molecular marker for Bacillus ecology study. AMB Express 2022; 12:133. [DOI: 10.1186/s13568-022-01477-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 10/15/2022] [Indexed: 11/10/2022] Open
Abstract
AbstractBacillus is a genus of microorganisms (bacteria) and contains many important commercial species used in industry, agriculture and healthcare. Many different Bacilli are relatively well understood at the single-cell level; however, molecular tools that determine the diversity and ecology of Bacillus community are limited, which limits our understanding of how the Bacillus community works. In the present study, we investigated the potential of the housekeeping gene gyrA as a molecular marker for determining the diversity of Bacillus species. The amplification efficiency for Bacillus species diversity could be greatly improved by primer design. Therefore, we designed a novel primer pair gyrA3 that can detect at least 92 Bacillus species and related species. For B. amyloliquefaciens, B. pumilus, and B. megaterium, we observed that the high variability of the gyrA gene allows for more detailed clustering at the subspecies level that cannot be achieved by the 16S rRNA gene. Since gyrA provides better phylogenetic resolution than 16S rRNA and informs on the diversity of the Bacillus community, we propose that the gyrA gene may have broad application prospects in the study of Bacillus ecology.
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Martini MC, Berini F, Ausec L, Casciello C, Vacca C, Pistorio M, Lagares A, Mandic-Mulec I, Marinelli F, Del Papa MF. Identification and Characterization of a Novel Plasmid-Encoded Laccase-Like Multicopper Oxidase from Ochrobactrum sp. BF15 Isolated from an On-Farm Bio-Purification System. Food Technol Biotechnol 2021; 59:519-529. [PMID: 35136375 PMCID: PMC8753806 DOI: 10.17113/ftb.59.04.21.7253] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 10/20/2021] [Indexed: 11/23/2022] Open
Abstract
RESEARCH BACKGROUND In recent decades, laccases (p-diphenol-dioxygen oxidoreductases; EC 1.10.3.2) have attracted the attention of researchers due to their wide range of biotechnological and industrial applications. Laccases can oxidize a variety of organic and inorganic compounds, making them suitable as biocatalysts in biotechnological processes. Even though the most traditionally used laccases in the industry are of fungal origin, bacterial laccases have shown an enormous potential given their ability to act on several substrates and in multiple conditions. The present study aims to characterize a plasmid-encoded laccase-like multicopper oxidase (LMCO) from Ochrobactrum sp. BF15, a bacterial strain previously isolated from polluted soil. EXPERIMENTAL APPROACH We used in silico profile hidden Markov models to identify novel laccase-like genes in Ochrobactrum sp. BF15. For laccase characterization, we performed heterologous expression in Escherichia coli, purification and activity measurement on typical laccase substrates. RESULTS AND CONCLUSIONS Profile hidden Markov models allowed us to identify a novel LMCO, named Lac80. In silico analysis of Lac80 revealed the presence of three conserved copper oxidase domains characteristic of three-domain laccases. We successfully expressed Lac80 heterologously in E. coli, allowing us to purify the protein for further activity evaluation. Of thirteen typical laccase substrates tested, Lac80 showed lower activity on 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), pyrocatechol, pyrogallol and vanillic acid, and higher activity on 2,6-dimethoxyphenol. NOVELTY AND SCIENTIFIC CONTRIBUTION Our results show Lac80 as a promising laccase for use in industrial applications. The present work shows the relevance of bacterial laccases and highlights the importance of environmental plasmids as valuable sources of new genes encoding enzymes with potential use in biotechnological processes.
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Affiliation(s)
- María Carla Martini
- IBBM - Institute of Biotechnology and Molecular Biology, CONICET - Department of Biological Sciences, Faculty of Exact Sciences, National University of La Plata, Calles 47 y 115 (1900) La Plata, Argentina
| | - Francesca Berini
- Department of Biotechnology and Life Sciences, University of Insubria, via J.H. Dunant 3, 21100 Varese, Italy
| | - Luka Ausec
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Carmine Casciello
- Department of Biotechnology and Life Sciences, University of Insubria, via J.H. Dunant 3, 21100 Varese, Italy
| | - Carolina Vacca
- IBBM - Institute of Biotechnology and Molecular Biology, CONICET - Department of Biological Sciences, Faculty of Exact Sciences, National University of La Plata, Calles 47 y 115 (1900) La Plata, Argentina
| | - Mariano Pistorio
- IBBM - Institute of Biotechnology and Molecular Biology, CONICET - Department of Biological Sciences, Faculty of Exact Sciences, National University of La Plata, Calles 47 y 115 (1900) La Plata, Argentina
| | - Antonio Lagares
- IBBM - Institute of Biotechnology and Molecular Biology, CONICET - Department of Biological Sciences, Faculty of Exact Sciences, National University of La Plata, Calles 47 y 115 (1900) La Plata, Argentina
| | - Ines Mandic-Mulec
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Flavia Marinelli
- Department of Biotechnology and Life Sciences, University of Insubria, via J.H. Dunant 3, 21100 Varese, Italy
| | - María Florencia Del Papa
- IBBM - Institute of Biotechnology and Molecular Biology, CONICET - Department of Biological Sciences, Faculty of Exact Sciences, National University of La Plata, Calles 47 y 115 (1900) La Plata, Argentina
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Danevčič T, Dragoš A, Spacapan M, Stefanic P, Dogsa I, Mandic-Mulec I. Surfactin Facilitates Horizontal Gene Transfer in Bacillus subtilis. Front Microbiol 2021; 12:657407. [PMID: 34054753 PMCID: PMC8160284 DOI: 10.3389/fmicb.2021.657407] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/07/2021] [Indexed: 11/14/2022] Open
Abstract
Genetic competence for the uptake and integration of extracellular DNA is a key process in horizontal gene transfer (HGT), one of the most powerful forces driving the evolution of bacteria. In several species, development of genetic competence is coupled with cell lysis. Using Bacillus subtilis as a model bacterium, we studied the role of surfactin, a powerful biosurfactant and antimicrobial lipopeptide, in genetic transformation. We showed that surfactin itself promotes cell lysis and DNA release, thereby promoting HGT. These results, therefore, provide evidence for a fundamental mechanism involved in HGT and significantly increase our understanding of the spreading of antibiotic resistance genes and diversification of microbial communities in the environment.
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Affiliation(s)
- Tjaša Danevčič
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Anna Dragoš
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
- Bacterial Interactions and Evolution Group, Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Mihael Spacapan
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Polonca Stefanic
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Iztok Dogsa
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Ines Mandic-Mulec
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
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Abstract
Research background The occurrence and environmental toxicity of pharmaceuticals have recently attracted increasing attention. Diclofenac is a highly consumed non-steroidal anti-inflammatory drug, which is often detected in wastewaters, but investigations of its influence on bacteria are scarce. Experimental approach We investigated the influence of this pharmaceutical on bacterial community in activated sludge exposed to increasing concentrations of diclofenac in fed-batch reactors over 41 days. Nitrification activity of the activated sludge was measured and changes in bacterial community structure were followed using culture-independent molecular method (terminal restriction fragment length polymorphism, T-RFLP) and by the cultivation approach. Results and conclusions Nitrification activity was not detectably influenced by the addition of diclofenac, while the main change of the bacterial community structure was detected only at the end of incubation (after 41 days) when diclofenac was added to artificial wastewater as the only carbon source. Changes in community composition due to enrichment were observed using cultivation approach. However, taxonomic affiliation of isolates did not match taxons identified by T-RFLP community profiling. Isolates obtained from activated sludge used as inoculum belonged to five genera: Comamonas, Arthrobacter, Acinetobacter, Citrobacter and Aeromonas, known for their potential to degrade aromatic compounds. However, only Pseudomonas species were isolated after the last enrichment step on minimal agar plates with diclofenac added as the sole carbon source. Novelty and scientific contribution Our results suggest that the selected recalcitrant and commonly detected pharmaceutical does not strongly influence the sensitive and important nitrification process of wastewater treatment. Moreover, the isolated strains obtained after enrichment procedure that were able to grow on minimal agar plates with diclofenac added as the only carbon source could serve as potential model bacteria to study bacterial diclofenac degradation.
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Affiliation(s)
- Barbara Kraigher
- University of Ljubljana, Biotechnical Faculty, Department of Food Science and Technology, Chair of Microbiology, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Ines Mandic-Mulec
- University of Ljubljana, Biotechnical Faculty, Department of Food Science and Technology, Chair of Microbiology, Večna pot 111, 1000 Ljubljana, Slovenia
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Xu Z, Mandic-Mulec I, Zhang H, Liu Y, Sun X, Feng H, Xun W, Zhang N, Shen Q, Zhang R. Antibiotic Bacillomycin D Affects Iron Acquisition and Biofilm Formation in Bacillus velezensis through a Btr-Mediated FeuABC-Dependent Pathway. Cell Rep 2020; 29:1192-1202.e5. [PMID: 31665633 DOI: 10.1016/j.celrep.2019.09.061] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 05/31/2019] [Accepted: 09/19/2019] [Indexed: 02/06/2023] Open
Abstract
Bacillus spp. produce a wide range of secondary metabolites, including antibiotics, which have been well studied for their antibacterial properties but less so as signaling molecules. Previous results indicated that the lipopeptide bacillomycin D is a signal that promotes biofilm development of Bacillus velezensis SQR9. However, the mechanism behind this signaling is still unknown. Here, we show that bacillomycin D promotes biofilm development by promoting the acquisition of iron. Bacillomycin D promotes the transcription of the iron ABC transporter FeuABC by binding to its transcription factor, Btr. These actions increase intracellular iron concentration and activate the KinB-Spo0A-SinI-SinR-dependent synthesis of biofilm matrix components. We demonstrate that this strategy is beneficial for biofilm development and competition with the Pseudomonas fluorescens PF-5. Our results unravel an antibiotic-dependent signaling mechanism that links iron acquisition to biofilm development and ecological competition.
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Affiliation(s)
- Zhihui Xu
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-Saving Fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples R China
| | - Ines Mandic-Mulec
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Huihui Zhang
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-Saving Fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples R China
| | - Yan Liu
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-Saving Fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples R China
| | - Xinli Sun
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-Saving Fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples R China
| | - Haichao Feng
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-Saving Fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples R China
| | - Weibing Xun
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-Saving Fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples R China
| | - Nan Zhang
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-Saving Fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples R China
| | - Qirong Shen
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-Saving Fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples R China
| | - Ruifu Zhang
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-Saving Fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples R China; Key Laboratory of Microbial Resource Collection and Preservation, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agriculture Sciences, Beijing, Peoples R China.
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Špacapan M, Danevčič T, Štefanic P, Porter M, Stanley-Wall NR, Mandic-Mulec I. The ComX Quorum Sensing Peptide of Bacillus subtilis Affects Biofilm Formation Negatively and Sporulation Positively. Microorganisms 2020; 8:E1131. [PMID: 32727033 PMCID: PMC7463575 DOI: 10.3390/microorganisms8081131] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/08/2020] [Accepted: 07/22/2020] [Indexed: 01/01/2023] Open
Abstract
Quorum sensing (QS) is often required for the formation of bacterial biofilms and is a popular target of biofilm control strategies. Previous studies implicate the ComQXPA quorum sensing system of Bacillus subtilis as a promoter of biofilm formation. Here, we report that ComX signaling peptide deficient mutants form thicker and more robust pellicle biofilms that contain chains of cells. We confirm that ComX positively affects the transcriptional activity of the PepsA promoter, which controls the synthesis of the major matrix polysaccharide. In contrast, ComX negatively controls the PtapA promoter, which drives the production of TasA, a fibrous matrix protein. Overall, the biomass of the mutant biofilm lacking ComX accumulates more monosaccharide and protein content than the wild type. We conclude that this QS phenotype might be due to extended investment into growth rather than spore development. Consistent with this, the ComX deficient mutant shows a delayed activation of the pre-spore specific promoter, PspoIIQ, and a delayed, more synchronous commitment to sporulation. We conclude that ComX mediated early commitment to sporulation of the wild type slows down biofilm formation and modulates the coexistence of multiple biological states during the early stages of biofilm development.
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Affiliation(s)
- Mihael Špacapan
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, 1000 Ljubljana, Slovenia; (M.Š.); (T.D.); (P.Š.)
| | - Tjaša Danevčič
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, 1000 Ljubljana, Slovenia; (M.Š.); (T.D.); (P.Š.)
| | - Polonca Štefanic
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, 1000 Ljubljana, Slovenia; (M.Š.); (T.D.); (P.Š.)
| | - Michael Porter
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK; (M.P.); (N.R.S.-W.)
| | - Nicola R. Stanley-Wall
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK; (M.P.); (N.R.S.-W.)
| | - Ines Mandic-Mulec
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, 1000 Ljubljana, Slovenia; (M.Š.); (T.D.); (P.Š.)
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11
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Spacapan M, Danevčič T, Mandic-Mulec I. Corrigendum: ComX-Induced Exoproteases Degrade ComX in Bacillus subtilis PS-216. Front Microbiol 2018; 9:1552. [PMID: 30008713 PMCID: PMC6038724 DOI: 10.3389/fmicb.2018.01552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 06/21/2018] [Indexed: 11/24/2022] Open
Affiliation(s)
- Mihael Spacapan
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Tjaša Danevčič
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Ines Mandic-Mulec
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
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12
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Abstract
Gram-positive bacteria use peptides as auto-inducing (AI) signals to regulate the production of extracellular enzymes (e.g., proteases). ComX is an AI peptide, mostly known for its role in the regulation of bacterial competence and surfactant production in Bacillus subtilis. These two traits are regulated accordingly to the bacterial population size, thus classifying ComX as a quorum sensing signal. ComX also indirectly regulates exoprotease production through the intermediate transcriptional regulator DegQ. We here use this peptide-based AI system (the ComQXPA system) as a model to address exoprotease regulation by ComX in biofilms. We also investigate the potential of ComX regulated proteases to degrade the ComX AI peptide. Results indicate that ComX indeed induces the expression of aprE, the gene for the major serine protease subtilisin, and stimulates overall exoprotease production in biofilms of B. subtilis PS-216 and several other B. subtilis soil isolates. We also provide evidence that these exoproteases can degrade ComX. The ComX biological activity decay is reduced in the spent media of floating biofilms with low proteolytic activity found in the comP and degQ mutants. ComX biological activity decay can be restored by the addition of subtilisin to such media. In contrast, inhibition of metalloproteases by EDTA reduces ComX biological activity decay. This suggests that both serine and metalloproteases, which are induced by ComX, are ultimately capable of degrading this signaling peptide. This work brings novel information on regulation of exoproteases in B. subtilis floating biofilms and reveals that these proteolytic enzymes degrade the AI signaling peptide ComX, which is also a major determinant of their expression in biofilms.
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Affiliation(s)
- Mihael Spacapan
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Tjaša Danevčič
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Ines Mandic-Mulec
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
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13
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Lyons NA, Kraigher B, Stefanic P, Mandic-Mulec I, Kolter R. A Combinatorial Kin Discrimination System in Bacillus subtilis. Curr Biol 2016; 26:733-42. [PMID: 26923784 PMCID: PMC4803606 DOI: 10.1016/j.cub.2016.01.032] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 12/03/2015] [Accepted: 01/13/2016] [Indexed: 12/31/2022]
Abstract
Multicellularity inherently involves a number of cooperative behaviors that are potentially susceptible to exploitation but can be protected by mechanisms such as kin discrimination. Discrimination of kin from non-kin has been observed in swarms of the bacterium Bacillus subtilis, but the underlying molecular mechanism has been unknown. We used genetic, transcriptomic, and bioinformatic analyses to uncover kin recognition factors in this organism. Our results identified many molecules involved in cell-surface modification and antimicrobial production and response. These genes varied significantly in expression level and mutation phenotype among B. subtilis strains, suggesting interstrain variation in the exact kin discrimination mechanism used. Genome analyses revealed a substantial diversity of antimicrobial genes present in unique combinations in different strains, with many likely acquired by horizontal gene transfer. The dynamic combinatorial effect derived from this plethora of kin discrimination genes creates a tight relatedness cutoff for cooperation that has likely led to rapid diversification within the species. Our data suggest that genes likely originally selected for competitive purposes also generate preferential interactions among kin, thus stabilizing multicellular lifestyles.
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Affiliation(s)
- Nicholas A Lyons
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA.
| | - Barbara Kraigher
- Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Polonca Stefanic
- Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Ines Mandic-Mulec
- Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Roberto Kolter
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA.
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14
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Nesme J, Achouak W, Agathos SN, Bailey M, Baldrian P, Brunel D, Frostegård Å, Heulin T, Jansson JK, Jurkevitch E, Kruus KL, Kowalchuk GA, Lagares A, Lappin-Scott HM, Lemanceau P, Le Paslier D, Mandic-Mulec I, Murrell JC, Myrold DD, Nalin R, Nannipieri P, Neufeld JD, O'Gara F, Parnell JJ, Pühler A, Pylro V, Ramos JL, Roesch LFW, Schloter M, Schleper C, Sczyrba A, Sessitsch A, Sjöling S, Sørensen J, Sørensen SJ, Tebbe CC, Topp E, Tsiamis G, van Elsas JD, van Keulen G, Widmer F, Wagner M, Zhang T, Zhang X, Zhao L, Zhu YG, Vogel TM, Simonet P. Back to the Future of Soil Metagenomics. Front Microbiol 2016; 7:73. [PMID: 26903960 PMCID: PMC4748112 DOI: 10.3389/fmicb.2016.00073] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 01/15/2016] [Indexed: 11/13/2022] Open
Affiliation(s)
- Joseph Nesme
- Environmental Microbial Genomics Group, Laboratoire Ampère, Centre National de la Recherche Scientifique, UMR5005, Institut National de la Recherche Agronomique, USC1407, Ecole Centrale de Lyon, Université de LyonEcully, France; Research Unit for Environmental Genomics, Helmholtz Zentrum München Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH)Neuherberg, Germany
| | - Wafa Achouak
- Aix-Marseille Université, CEA, Centre National de la Recherche Scientifique, Laboratoire d'Écologie Microbienne de la Rhizosphère et Environnements Extrêmes, UMR 7265, Biologie Végétale et de Microbiologie Environnementales Saint-Paul-lez-Durance, France
| | - Spiros N Agathos
- Earth and Life Institute, Catholic University of LouvainLouvain-la-Neuve, Belgium; School of Life Sciences and Biotechnology, Yachay Tech UniversityUrcuquí, Ecuador
| | - Mark Bailey
- Natural Environment Research Council, Centre for Ecology and Hydrology Oxford, UK
| | - Petr Baldrian
- Laboratory of Environmental Microbiology, Institute of Microbiology of the Czech Academy of Sciences Praha, Czech Republic
| | - Dominique Brunel
- Institut National de la Recherche Agronomique, US1279, Etude du Polymorphisme des Génomes Végétaux, CEA, Institut de Génomique, Centre National de Génotypage Evry, France
| | - Åsa Frostegård
- NMBU Nitrogen Group, Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences Aas, Norway
| | - Thierry Heulin
- Aix-Marseille Université, CEA, Centre National de la Recherche Scientifique, Laboratoire d'Écologie Microbienne de la Rhizosphère et Environnements Extrêmes, UMR 7265, Biologie Végétale et de Microbiologie Environnementales Saint-Paul-lez-Durance, France
| | - Janet K Jansson
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory Richland, WA, USA
| | - Edouard Jurkevitch
- Department of Plant Pathology and Microbiology, The Faculty of Agriculture, Food and Environment, The Otto Warburg-Minerva Center in Agricultural Biotechnology, The Hebrew University of Jerusalem Rehovot, Israel
| | - Kristiina L Kruus
- Enzymology of Renewable Biomass, VTT, Technical Research Centre of Finland Espoo, Finland
| | - George A Kowalchuk
- Ecology and Biodiversity, Institute of Environmental Biology, Utrecht University Utrecht, Netherlands
| | - Antonio Lagares
- Departamento de Ciencia Biológicas, Facultad de Ciencias Exactas, Instituto de Biotecnología y Biología Molecular, Centro Científico Tecnológico-Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de La Plata La Plata, Argentina
| | | | - Philippe Lemanceau
- Institut National de la Recherche Agronomique, UMR 1347, Agroécologie, Université de Bourgogne Dijon, France
| | - Denis Le Paslier
- CEA/Direction des sciences du vivant/Institut de Génomique. Genoscope, Centre National de la Recherche Scientifiue UMR 8030, Université d'Evry Val d'Essonne Evry, France
| | - Ines Mandic-Mulec
- Department of Food Science and Technology, Biotechnical Faculty- University of Ljubljana Ljubljana, Slovenia
| | - J Colin Murrell
- School of Environmental Sciences, University of East Anglia Norwich, UK
| | - David D Myrold
- Department of Crop and Soil Science, Oregon State University Corvallis, OR, USA
| | | | - Paolo Nannipieri
- Department of Agrifood and Environmental Science, University of Florence Florence, Italy
| | - Josh D Neufeld
- Department of Biology, University of Waterloo Waterloo, ON, Canada
| | - Fergal O'Gara
- BIOMERIT Research Centre, School of Microbiology, National University of IrelandCork, Ireland; School of Biomedical Science, Curtin UniversityPerth, WA, Australia
| | - John J Parnell
- National Ecological Observatory Network Boulder, CO, USA
| | - Alfred Pühler
- Center for Biotechnology, Institute for Genome Research and Systems Biology, Genome Research of Industrial Microorganisms, Bielefeld University Bielefeld, Germany
| | - Victor Pylro
- Genomics and Computational Biology Group, René Rachou Research Centre - CPqRR/FIOCRUZ Belo Horizonte, Brazil
| | - Juan L Ramos
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas Granada, Spain
| | | | - Michael Schloter
- Research Unit for Environmental Genomics, Helmholtz Zentrum München Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH) Neuherberg, Germany
| | - Christa Schleper
- Archaea Biology and Ecogenomics Division, Department of Ecogenomics and Systems Biology, University of Vienna Vienna, Austria
| | - Alexander Sczyrba
- Center for Biotechnology and Faculty of Technology, Computational Metagenomics, Bielefeld University Bielefeld, Germany
| | - Angela Sessitsch
- Health and Environment Department, Bioresources, AIT Austrian Institute of Technology GmbH Tulln, Austria
| | - Sara Sjöling
- School of Natural Sciences and Environmental Studies, Södertörn University Huddinge, Sweden
| | - Jan Sørensen
- Section of Genetics and Microbiology, Department of Plant and Environmental Microbiology, University of Copenhagen Frederiksberg, Denmark
| | - Søren J Sørensen
- Section of Microbiology, Department of Biology, University of Copenhagen Copenhagen, Denmark
| | | | - Edward Topp
- Agriculture and Agri-Food Canada, Department of Biology, University of Western Ontario London, ON, Canada
| | - George Tsiamis
- Department of Environmental and Natural Resources Management, University of Patras Agrinio, Greece
| | - Jan Dirk van Elsas
- Department of Microbial Ecology, Groningen Institute for Evolutionary Life Sciences, University of Groningen Groningen, Netherlands
| | - Geertje van Keulen
- Institute of Life Science, Medical School, Swansea University Swansea, UK
| | - Franco Widmer
- Molecular Ecology, Institute for Sustainability Sciences, Agroscope Zürich, Switzerland
| | - Michael Wagner
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna Vienna, Austria
| | - Tong Zhang
- Environmental Biotechnology Laboratory, Department of Civil Engineering, The University of Hong Kong Hong Kong, China
| | - Xiaojun Zhang
- Group of Microbial Ecology and Ecogenomics, State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University Shanghai, China
| | - Liping Zhao
- Group of Microbial Ecology and Ecogenomics, State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University Shanghai, China
| | - Yong-Guan Zhu
- Institute of Urban Environment, Chinese Academy of Sciences Xiamen, China
| | - Timothy M Vogel
- Environmental Microbial Genomics Group, Laboratoire Ampère, Centre National de la Recherche Scientifique, UMR5005, Institut National de la Recherche Agronomique, USC1407, Ecole Centrale de Lyon, Université de Lyon Ecully, France
| | - Pascal Simonet
- Institute of Life Science, Medical School, Swansea University Swansea, UK
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15
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Oslizlo A, Stefanic P, Vatovec S, Beigot Glaser S, Rupnik M, Mandic-Mulec I. Exploring ComQXPA quorum-sensing diversity and biocontrol potential of Bacillus spp. isolates from tomato rhizoplane. Microb Biotechnol 2015; 8:527-40. [PMID: 25757097 PMCID: PMC4408185 DOI: 10.1111/1751-7915.12258] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 11/20/2014] [Accepted: 12/03/2014] [Indexed: 01/06/2023] Open
Abstract
Bacillus subtilis is a widespread and diverse bacterium t exhibits a remarkable intraspecific diversity of the ComQXPA quorum-sensing (QS) system. This manifests in the existence of distinct communication groups (pherotypes) that can efficiently communicate within a group, but not between groups. Similar QS diversity was also found in other bacterial species, and its ecological and evolutionary meaning is still being explored. Here we further address the ComQXPA QS diversity among isolates from the tomato rhizoplane, a natural habitat of B. subtilis, where these bacteria likely exist in their vegetative form. Because this QS system regulates production of anti-pathogenic and biofilm-inducing substances such as surfactins, knowledge on cell-cell communication of this bacterium within rhizoplane is also important from the biocontrol perspective. We confirm the presence of pherotype diversity within B. subtilis strains isolated from a rhizoplane of a single plant. We also show that B. subtilis rhizoplane isolates show a remarkable diversity of surfactin production and potential plant growth promoting traits. Finally, we discover that effects of surfactin deletion on biofilm formation can be strain specific and unexpected in the light of current knowledge on its role it this process.
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Affiliation(s)
- A Oslizlo
- Department of Food Science and Technology, Biotechnical Faculty, University of LjubljanaLjubljana, Slovenia
| | - P Stefanic
- Department of Food Science and Technology, Biotechnical Faculty, University of LjubljanaLjubljana, Slovenia
| | - S Vatovec
- Department of Food Science and Technology, Biotechnical Faculty, University of LjubljanaLjubljana, Slovenia
| | - S Beigot Glaser
- National Laboratory for Health, Environment and FoodMaribor, Slovenia
| | - M Rupnik
- National Laboratory for Health, Environment and FoodMaribor, Slovenia
- Faculty of Medicine, University of MariborMaribor, Slovenia
- Centre of Excellence for Integrated Approaches in Chemistry and Biology of ProteinsLjubljana, Slovenia
| | - I Mandic-Mulec
- Department of Food Science and Technology, Biotechnical Faculty, University of LjubljanaLjubljana, Slovenia
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16
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Dogsa I, Choudhary KS, Marsetic Z, Hudaiberdiev S, Vera R, Pongor S, Mandic-Mulec I. ComQXPA quorum sensing systems may not be unique to Bacillus subtilis: a census in prokaryotic genomes. PLoS One 2014; 9:e96122. [PMID: 24788106 PMCID: PMC4008528 DOI: 10.1371/journal.pone.0096122] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Accepted: 04/03/2014] [Indexed: 11/19/2022] Open
Abstract
The comQXPA locus of Bacillus subtilis encodes a quorum sensing (QS) system typical of Gram positive bacteria. It encodes four proteins, the ComQ isoprenyl transferase, the ComX pre-peptide signal, the ComP histidine kinase, and the ComA response regulator. These are encoded by four adjacent genes all situated on the same chromosome strand. Here we present results of a comprehensive census of comQXPA-like gene arrangements in 2620 complete and 6970 draft prokaryotic genomes (sequenced by the end of 2013). After manually checking the data for false-positive and false-negative hits, we found 39 novel com-like predictions. The census data show that in addition to B. subtilis and close relatives, 20 comQXPA-like loci are predicted to occur outside the B. subtilis clade. These include some species of Clostridiales order, but none outside the phylum Firmicutes. Characteristic gene-overlap patterns were observed in comQXPA loci, which were different for the B. subtilis-like and non-B. subtilis-like clades. Pronounced sequence variability associated with the ComX peptide in B. subtilis clade is evident also in the non-B. subtilis clade suggesting grossly similar evolutionary constraints in the underlying quorum sensing systems.
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Affiliation(s)
- Iztok Dogsa
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Kumari Sonal Choudhary
- Group of Protein Structure and Bioinformatics, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Ziva Marsetic
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Sanjarbek Hudaiberdiev
- Group of Protein Structure and Bioinformatics, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Roberto Vera
- Group of Protein Structure and Bioinformatics, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
| | - Sándor Pongor
- Group of Protein Structure and Bioinformatics, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
- * E-mail: (SP); (IMM)
| | - Ines Mandic-Mulec
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
- * E-mail: (SP); (IMM)
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17
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Jacquiod S, Demanèche S, Franqueville L, Ausec L, Xu Z, Delmont TO, Dunon V, Cagnon C, Mandic-Mulec I, Vogel TM, Simonet P. Characterization of new bacterial catabolic genes and mobile genetic elements by high throughput genetic screening of a soil metagenomic library. J Biotechnol 2014; 190:18-29. [PMID: 24721211 DOI: 10.1016/j.jbiotec.2014.03.036] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 03/24/2014] [Accepted: 03/28/2014] [Indexed: 11/27/2022]
Abstract
A mix of oligonucleotide probes was used to hybridize soil metagenomic DNA from a fosmid clone library spotted on high density membranes. The pooled radio-labeled probes were designed to target genes encoding glycoside hydrolases GH18, dehalogenases, bacterial laccases and mobile genetic elements (integrases from integrons and insertion sequences). Positive hybridizing spots were affiliated to the corresponding clones in the library and the metagenomic inserts were sequenced. After assembly and annotation, new coding DNA sequences related to genes of interest were identified with low protein similarity against the closest hits in databases. This work highlights the sensitivity of DNA/DNA hybridization techniques as an effective and complementary way to recover novel genes from large metagenomic clone libraries. This study also supports that some of the identified catabolic genes might be associated with horizontal transfer events.
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Affiliation(s)
- Samuel Jacquiod
- Environmental Microbial Genomics Group, Laboratoire Ampère, CNRS, École Centrale de Lyon, Université de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully, France.
| | - Sandrine Demanèche
- Environmental Microbial Genomics Group, Laboratoire Ampère, CNRS, École Centrale de Lyon, Université de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully, France
| | - Laure Franqueville
- Environmental Microbial Genomics Group, Laboratoire Ampère, CNRS, École Centrale de Lyon, Université de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully, France
| | - Luka Ausec
- Department for Food Science and Technology Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Zhuofei Xu
- Molecular Microbial Ecology Group, Section of Microbiology, København Universitet, København, Denmark
| | - Tom O Delmont
- Environmental Microbial Genomics Group, Laboratoire Ampère, CNRS, École Centrale de Lyon, Université de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully, France
| | - Vincent Dunon
- Division of Soil and Water Management, Department of Earth and Environmental Sciences, University of Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium
| | - Christine Cagnon
- Équipe Environnement et Microbiologie, IBEAS - UFR Sciences et Techniques, Université de Pau et des Pays de l'Adour, 64013 Pau, France
| | - Ines Mandic-Mulec
- Department for Food Science and Technology Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Timothy M Vogel
- Environmental Microbial Genomics Group, Laboratoire Ampère, CNRS, École Centrale de Lyon, Université de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully, France
| | - Pascal Simonet
- Environmental Microbial Genomics Group, Laboratoire Ampère, CNRS, École Centrale de Lyon, Université de Lyon, 36 Avenue Guy de Collongue, 69134 Ecully, France.
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18
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Filipič J, Kraigher B, Tepuš B, Kokol V, Mandic-Mulec I. Effects of low-density static magnetic fields on the growth and activities of wastewater bacteria Escherichia coli and Pseudomonas putida. Bioresour Technol 2012; 120:225-232. [PMID: 22820111 DOI: 10.1016/j.biortech.2012.06.023] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Revised: 06/04/2012] [Accepted: 06/06/2012] [Indexed: 06/01/2023]
Abstract
The aim of this study was to explore the influence of a moderate static magnetic field (SMF) of different densities on Escherichia coli and Pseudomonas putida that are commonly found in wastewater treatment plants. In line with literature reports that SMF increases the efficiency of wastewater treatment the findings of this study indicated that SMF negatively influenced the growth but positively influenced the enzymatic activities and ATP levels of the two model bacteria. The inhibitory effect of SMF on growth of E. coli and P. putida was most pronounced at their optimal growth temperature (37°C and 28°C respectively) and was reversible shortly after the SMF had been terminated. Finally, the results suggested that the induced energy metabolism reflected in higher dehydrogenase activities and ATP levels may be more important for survival, and adaptation to SMF induced stress than the increase in the expression of the rpoS gene.
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Affiliation(s)
- Jasmina Filipič
- Ptuj Municipal Service Corporation, Puhova ulica 10, SI-2250 Ptuj, Slovenia
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19
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Pal L, Kraigher B, Brajer-Humar B, Levstek M, Mandic-Mulec I. Total bacterial and ammonia-oxidizer community structure in moving bed biofilm reactors treating municipal wastewater and inorganic synthetic wastewater. Bioresour Technol 2012; 110:135-143. [PMID: 22342033 DOI: 10.1016/j.biortech.2012.01.130] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 01/20/2012] [Accepted: 01/24/2012] [Indexed: 05/31/2023]
Abstract
Industrial-scale bioreactors treat wastewater of temporally variable composition under different weather conditions, while the microbial populations of wastewater treatment plants are often studied in controlled laboratory-scale systems with defined influent at a constant temperature. 16S rRNA- and ammonia oxidising amoA-gene-defined bacterial community structure was investigated in industrial and laboratory-scale moving bed biofilm bioreactors (MBBRs) treating municipal wastewater (WW) or synthetic ammonium solution (AS). Nitrification activity, 16S rRNA and amoA gene T-RFLP profiles were comparable between industrial and laboratory scale WW bioreactors. AS bioreactors exhibited higher nitrification and higher relative abundances of Nitrosomonadaceae and Nitrospiraceae families but only small changes in the general bacterial community structure was detected compared to WW MBBRs. Nitrosomonas europaea lineage dominated WW, while uncultivated Nitrosomonas-like sequences prevailed in AS bioreactors. These results suggest that influent type has a stronger influence on community structure than operational conditions, such as temperature or bioreactor size.
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Affiliation(s)
- Levin Pal
- University of Ljubljana, Biotechnical Faculty, Department of Food Science and Technology, Vecna pot 111, 1000 Ljubljana, Slovenia
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Stefanic P, Decorosi F, Viti C, Petito J, Cohan FM, Mandic-Mulec I. The quorum sensing diversity within and between ecotypes of Bacillus subtilis. Environ Microbiol 2012; 14:1378-89. [PMID: 22390407 DOI: 10.1111/j.1462-2920.2012.02717.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ecological sociobiology is an emerging field that aims to frame social evolution in terms of ecological adaptation. Here we explore the ecological context for evolution of quorum sensing diversity in bacteria, where social communication is limited to members of the same quorum sensing type (pherotype). We sampled isolates of Bacillus subtilis from soil on a microgeographical scale and identified three ecologically distinct phylogenetic groups (ecotypes) and three pherotypes. Each pherotype was strongly associated with a different ecotype, suggesting that it is usually not adaptive for one ecotype to 'listen' to the signalling of another. Each ecotype, however, contained one or more minority pherotypes shared with the other B. subtilis ecotypes and with more distantly related species taxa. The pherotype diversity within ecotypes is consistent with two models: first, a pherotype cycling model, whereby minority pherotypes enter a population through horizontal genetic transfer and increase in frequency through cheating the social interaction; and second, an occasional advantage model, such that when two ecotypes are each below their quorum densities, they may benefit from listening to one another. This is the first survey of pherotype diversity in relation to ecotypes and it will be interesting to further test the hypotheses raised and supported here, and to explore other bacterial systems for the role of ecological divergence in fostering pherotype diversity.
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Affiliation(s)
- Polonca Stefanic
- Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia Department of Agricultural Biotechnology, University of Florence, Florence, Italy
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Kraigher B, Mandic-Mulec I. Nitrification activity and community structure of nitrite-oxidizing bacteria in the bioreactors operated with addition of pharmaceuticals. J Hazard Mater 2011; 188:78-84. [PMID: 21316843 DOI: 10.1016/j.jhazmat.2011.01.072] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Revised: 01/14/2011] [Accepted: 01/14/2011] [Indexed: 05/30/2023]
Abstract
Pharmaceuticals represent a group of the new emerging contaminants, which might influence microbial communities in the activated sludge. Nitrification activity and Nitrospira community structure in the small-scale reactors supplied with different concentrations (0, 50, 200, 500 μg L(-1)) of the selected pharmaceuticals (ibuprofen, naproxen, ketoprofen, diclofenac and clofibric acid) were evaluated. Ammonia removal was not influenced by selected pharmaceuticals. However, in the two reactors operated with 50 μg L(-1) of pharmaceuticals (R50 and R50P), the effluent concentration of N-(NO(2)(-)+NO(3)(-)) was significantly higher than in the other reactors. Nitrospira community structure was assessed by terminal restriction fragment length polymorphism (T-RFLP) and by cloning and sequencing of the partial genes for 16S rRNA. Nitrospira spp. were detected in all reactors. The two dominant T-RFs represented the sublineages I and II of the genus Nitrospira. Main shifts were observed in the reactors R50 and R50P, where the T-RF representing sublineage II was much higher as compared to the other reactors. Consistent with this, the Nitrospira sublineage II was detected only in the clone libraries from the reactors R50 and R50P. Our results suggest that the relative abundance of Nitrospira sublineage II could be related to the effluent N-(NO(2)(-)+NO(3)(-)) concentration.
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Affiliation(s)
- Barbara Kraigher
- Biotechnical Faculty, Department of Food Science and Technology, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia.
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Kraigher B, Kosjek T, Heath E, Kompare B, Mandic-Mulec I. Influence of pharmaceutical residues on the structure of activated sludge bacterial communities in wastewater treatment bioreactors. Water Res 2008; 42:4578-4588. [PMID: 18786690 DOI: 10.1016/j.watres.2008.08.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Revised: 08/01/2008] [Accepted: 08/04/2008] [Indexed: 05/26/2023]
Abstract
Concern is growing over contamination of the environment with pharmaceuticals because of their widespread use and incomplete removal during wastewater treatment, where microorganisms drive the key processes. The influence of pharmaceuticals on bacterial community structure in activated sludge was assessed in small-scale wastewater treatment bioreactors containing different concentrations (5, 50, 200 and 500microgL(-1)) of several commonly used pharmaceuticals (ibuprofen, naproxen, ketoprofen, diclofenac and clofibric acid). T-RFLP analyses of the bacterial 16S rRNA genes indicated a minor but consistent shift in the bacterial community structure in the bioreactor R50 supplied with pharmaceuticals at a concentration of 50microgL(-1), compared to the control reactor R0, which was operated without addition of pharmaceuticals. In the reactors operated with higher concentrations of pharmaceuticals, a greater structural divergence was observed. Bacterial community composition was further investigated by preparation of two clone libraries of bacterial 16S rRNA genes from reactors R0 and R50. Most clones in both libraries belonged to the Betaproteobacteria, among which Thauera, Sphaerotilus, Ideonella and Acidovorax-related spp. dominated. Nitrite-oxidizing bacteria of the genus Nitrospira sp., which are key organisms for the second stage of nitrification in wastewater treatment plants, were found only in the clone library of the reactor without pharmaceuticals. In addition, diversity indices were calculated for the two clone libraries, indicating a reduced diversity of activated sludge bacterial community in the reactor supplied with 50microgL(-1) of each of selected pharmaceuticals.
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MESH Headings
- Bacteria/classification
- Bacteria/genetics
- Bacteria/metabolism
- Bioreactors
- Cloning, Molecular
- DNA, Bacterial/genetics
- DNA, Bacterial/isolation & purification
- Drug Residues/metabolism
- Escherichia coli/genetics
- Escherichia coli/isolation & purification
- Genetic Variation
- Phylogeny
- Polymorphism, Restriction Fragment Length
- RNA, Bacterial/genetics
- RNA, Bacterial/isolation & purification
- RNA, Ribosomal, 16S/genetics
- RNA, Ribosomal, 16S/isolation & purification
- Sewage/microbiology
- Waste Disposal, Fluid/methods
- Water Purification/methods
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Affiliation(s)
- Barbara Kraigher
- Chair of Microbiology, Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
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Stres B, DanevÄiÄ T, Pal L, Fuka MM, Resman L, Leskovec S, Hacin J, Stopar D, Mahne I, Mandic-Mulec I. Influence of temperature and soil water content on bacterial, archaeal and denitrifying microbial communities in drained fen grassland soil microcosms. FEMS Microbiol Ecol 2008; 66:110-22. [DOI: 10.1111/j.1574-6941.2008.00555.x] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Albano M, Smits WK, Ho LTY, Kraigher B, Mandic-Mulec I, Kuipers OP, Dubnau D. The Rok protein of Bacillus subtilis represses genes for cell surface and extracellular functions. J Bacteriol 2005; 187:2010-9. [PMID: 15743949 PMCID: PMC1064057 DOI: 10.1128/jb.187.6.2010-2019.2005] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rok is a repressor of the transcriptional activator ComK and is therefore an important regulator of competence in Bacillus subtilis (T. T. Hoa, P. Tortosa, M. Albano, and D. Dubnau, Mol. Microbiol. 43:15-26, 2002). To address the wider role of Rok in the physiology of B. subtilis, we have used a combination of transcriptional profiling, gel shift experiments, and the analysis of lacZ fusions. We demonstrate that Rok is a repressor of a family of genes that specify membrane-localized and secreted proteins, including a number of genes that encode products with antibiotic activity. We present evidence for the recent introduction of rok into the B. subtilis-Bacillus licheniformis-Bacilllus amyloliquefaciens group by horizontal transmission.
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Affiliation(s)
- Mark Albano
- Public Health Research Institute, Newark, NJ 07103, USA
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Abstract
Natural genetic competence in Bacillus subtilis is controlled by quorum-sensing (QS). The ComP- ComA two-component system detects the signalling molecule ComX, and this signal is transduced by a conserved phosphotransfer mechanism. ComX is synthesized as an inactive precursor and is then cleaved and modified by ComQ before export to the extracellular environment. The comQXP' loci of a set of natural Bacillus isolates have been sequenced and shown to possess a striking polymorphism that determines specific patterns of both activation and inhibition of the quorum-sensing response. We have developed a simple purification method for the modified peptide signalling pheromones allowing the characterization of four distinct ComX molecules representing different pherotypes. Genetic and biochemical evidence demonstrate that all the ComX variants are isoprenylated by the post-translational modification of a conserved tryptophan residue and that the modifications on the ComX peptide backbones vary in mass among the various pherotypes. These results give new insights into peptidemediated quorum-sensing signalling in Gram-positive bacteria and emphasize the role of isoprenylation in bacterial signal transduction.
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Affiliation(s)
- Mireille Ansaldi
- Public Health Research Institute, 225 Warren Street, Newark, NJ 07103, USA
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Abstract
ComK, the master regulator of competence, is degraded by the general stress-related protease ClpCP but must be targeted to this protease by binding to the adapter protein MecA. The genome of Bacillus subtilis contains a paralog of mecA, ypbH. We show in the present study that YpbH, like MecA, binds ClpC and that its elimination or overproduction affects competence and sporulation.
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Affiliation(s)
- Marjan Persuh
- Public Health Research Institute, New York, New York 10016, USA
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Prohinar P, Forst SA, Reed D, Mandic-Mulec I, Weiss J. OmpR-dependent and OmpR-independent responses of Escherichia coli to sublethal attack by the neutrophil bactericidal/permeability increasing protein. Mol Microbiol 2002; 43:1493-504. [PMID: 11952900 DOI: 10.1046/j.1365-2958.2002.02804.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Bactericidal/permeability-increasing protein (BPI) of neutrophils is a lipopolysaccharide (LPS)-binding antibacterial protein with specificity for Gram negative bacteria. BPI binding to the bacterial surface rapidly triggers potentially reversible bacterial growth inhibition and alterations of the outer membrane and, later, disruption of the inner membrane and lethal injury. Initial effects include selective OmpR-dependent changes in the synthesis of outer membrane porins (OmpF and OmpC). Because OmpR is a global transcriptional regulator, we have examined its possible role in responses of E. coli to sublethal injury caused by BPI. Early (<15 min) reversible effects of BPI on bacterial colony-forming ability and outer membrane permeability were virtually identical in isogenic wild-type (wt) and ompR- E. coli. Both strains could repair the outer membrane permeability barrier after Mg2+-induced displacement of bound BPI. However, OmpR was essential for the ability of E. coli to tolerate low doses of BPI and escape the progression of sublethal to lethal damage. Scanning electron microscopy revealed that BPI treatment produced greater membrane perturbations in the ompR- strain, apparent even before lethal injury. These findings suggest that the fate of E. coli exposed to BPI depends on both OmpR-independent mechanisms engaged in outer membrane repair and OmpR- dependent processes that modulate porin synthesis and retard progression of injury from the outer to the inner membrane.
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Affiliation(s)
- Polonca Prohinar
- Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA
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Abstract
The expression of many gene products required during the early stages of Bacillus subtilis sporulation is regulated by sinIR operon proteins. Transcription of sinIR from the P1 promoter is induced at the end of exponential growth. In vivo transcription studies suggest that P1 induction is repressed by the transition-state regulatory protein Hpr and is induced by the phosphorylated form of Spo0A. In vitro DNase I footprinting studies confirmed that Hpr, AbrB, and Spo0A are trans-acting transcriptional factors that bind to the P1 promoter region of sinIR. We have also determined that the P1 promoter is transcribed in vitro by the major vegetative sigma factor, final sigma(A), form of RNA polymerase.
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Affiliation(s)
- Sasha H Shafikhani
- Department of Molecular and Cellular Biology, Division of Biochemistry and Molecular Biology, University of California, Berkeley, California 94720, USA
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Tortosa P, Logsdon L, Kraigher B, Itoh Y, Mandic-Mulec I, Dubnau D. Specificity and genetic polymorphism of the Bacillus competence quorum-sensing system. J Bacteriol 2001; 183:451-60. [PMID: 11133937 PMCID: PMC94899 DOI: 10.1128/jb.183.2.451-460.2001] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A quorum-sensing mechanism involving the pheromone ComX and the ComP-ComA two-component system controls natural competence in Bacillus subtilis. ComX is expressed as a cytoplasmic inactive precursor that is released into the extracellular medium as a cleaved, modified decapeptide. This process requires the product of comQ. In the presence of ComX, the membrane-localized ComP histidine kinase activates the response regulator ComA. We compared the sequences of the quorum-sensing genes from four closely related bacilli, and we report extensive genetic polymorphism extending through comQ, comX, and the 5' two-thirds of comP. This part of ComP encodes the membrane-localized and linker domains of the sensor protein. We also determined the sequences of the comX genes of four additional wild-type bacilli and tested the in vivo activities of all eight pheromones on isogenic strains containing four different ComP receptor proteins. A striking pattern of specificity was discovered, providing strong evidence that the pheromone contacts ComP directly. Furthermore, we show that coexpression of comQ and comX in Escherichia coli leads to the production of active pheromone in the medium, demonstrating that comQ is the only dedicated protein required for the processing, modification, and release of active competence pheromone. Some of the implications of these findings for the evolution and the mechanism of the quorum-sensing system are discussed.
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Affiliation(s)
- P Tortosa
- Public Health Research Institute, New York, New York 10016, USA
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Abstract
ComK is a transcription factor required for the expression of competence genes in Bacillus subtilis. Binding to MecA targets ComK for degradation by the ClpCP protease. MecA therefore acts as an adapter protein recruiting a regulatory protein for proteolysis. However, when ComS is synthesized, ComK is released from binding by MecA and thereby protected from degradation. MecA binds to three protein partners during these processes: ComK, ClpC and ComS. Using limited proteolysis, we have defined N- and C-terminal structural domains of MecA and evaluated the interactions of these domains with the protein partners of MecA. Using surface plasmon resonance, we have determined that the N-terminal domain of MecA interacts with ComK and ComS and the C-terminal domain with ClpC. MecA is shown to exist as a dimer with dimerization sites on both the N- and C-terminal domains. The C-terminal domain stimulates the ATPase activity of ClpC and is degraded by the ClpCP protease, while the N-terminal domain is inactive in both of these assays. In vivo data were consistent with these findings, as comG-lacZ expression was decreased in a strain overproducing the N-terminal domain, indicating reduced ComK activity. We propose a model in which binding of ClpC to the C-terminal domain of MecA induces a conformational change enabling the N-terminal domain to bind ComK with enhanced affinity. MecA is widespread among Gram-positive organisms and may act generally as an adapter protein, targeting proteins for regulated degradation.
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Affiliation(s)
- M Persuh
- Public Health Research Institute, 455 First Avenue, New York, NY 10016, USA.; University of Ljubljana, 1000 Ljubljana, Slovenia
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Abstract
We examined the bactericidal activity of polymorphonuclear leukocytes (PMN) against an invasive wild-type strain of Shigella flexneri (M90T) and a plasmid-cured noninvasive derivative (BS176). Both Shigella strains, as well as a rough strain of Escherichia coli, were killed with similar efficiencies by intact inflammatory PMN in room air and under N2 (i.e., killing was O2 independent). Bacterial killing by PMN extracts was substantially inhibited by antibodies to the bactericidal/permeability-increasing protein (BPI). Whereas wild-type Shigella escapes from the phagosome to the cytoplasm in epithelial cells and macrophages, wild-type Shigella was trapped in the phagolysosome of PMN as visualized by electron microscopy. The efficient killing of Shigella by PMN suggests that these inflammatory cells may not only contribute initially to the severe tissue damage characteristic of shigellosis but also ultimately participate in clearance and resolution of infection.
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Affiliation(s)
- I Mandic-Mulec
- The Skirball Institute, New York University School of Medicine, New York, New York 10016, USA
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Abstract
We have previously described sigma A and sigma B and their structural genes, mysA and mysB, respectively, in Mycobacterium smegmatis. We have now sequenced the corresponding regions in the M. tuberculosis and M. leprae chromosomes, and have found the two homologous genes. The chromosomal linkage and the deduced amino acid (aa) sequences of the two genes show very high similarity in the three species of mycobacteria. We also report the finding of two other open reading frames (ORF) in these clusters. orfX, which has an unknown function, is located between mysA and mysB. The other ORF, located downstream from mysB, encodes a homolog of DtxR, the iron regulatory protein from Corynebacterium diphtheriae (Cd).
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Affiliation(s)
- L Doukhan
- Department of Microbiology, Public Health Research Institute, New York, NY 10016, USA
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Abstract
SinR is a pleiotropic DNA binding protein that is essential for the late-growth processes of competence and motility in Bacillus subtilis and is also a repressor of others, e.g., sporulation and subtilisin synthesis. In this report, we show that SinR, in addition to being an inhibitor of sporulation stage II gene expression, is a repressor of the key early sporulation gene spo0A. The sporulation-specific rise in spo0A expression at time zero is absent in a SinR-overproducing strain and is much higher than normal in strains with a disrupted sinR gene. This effect is direct, since SinR binds specifically to spo0A in vitro, in a region overlapping the -10 region of the sporulation-specific Ps promoter that is recognized by E-sigma H polymerase. Methyl interference and site-directed mutagenesis studies have identified guanine residues that are important for SinR recognition of this DNA sequence. Finally, we present evidence that SinR controls sporulation through several independent genes, i.e., sp0A, spoIIA, and possibly spoIIG and spoIIE.
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Affiliation(s)
- I Mandic-Mulec
- Public Health Research Institute, New York, New York 10016, USA
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Bai U, Mandic-Mulec I, Smith I. SinI modulates the activity of SinR, a developmental switch protein of Bacillus subtilis, by protein-protein interaction. Genes Dev 1993; 7:139-48. [PMID: 8422983 DOI: 10.1101/gad.7.1.139] [Citation(s) in RCA: 162] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
SinR, a 111-amino-acid DNA-binding protein, is a pleiotropic regulator of several late growth processes in Bacillus subtilis. It acts as a developmental switch, positively regulating genes for competence and motility and repressing aprE and stage II sporulation genes. It is encoded by the second gene in a two gene operon, but previous results have also indicated that these two genes are differently regulated. We show in this discussion that the product of sinI, the first open reading frame (ORF) of this operon, interferes with the function of SinR. In vivo experiments have demonstrated that overexpression of sinI results in phenotypes that are observed in cells with a null mutation of sinR. A chromosomal in-frame deletion of sinI gives rise to a phenotype associated with higher levels of SinR. Thus, SinI acts as an antagonist to SinR. In vitro experiments have shown that the interaction between these two proteins is a direct one. SinI prevents SinR from binding to its target sequence on aprE, and the two proteins form a complex that can be immunoprecipitated with antibodies to either SinR or SinI.
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Affiliation(s)
- U Bai
- Department of Microbiology, New York University Medical Center, New York 10016
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Abstract
Sin is a Bacillus subtilis DNA-binding protein which is essential for competence, motility, and autolysin production but also, if expressed on a multicopy plasmid, is inhibitory to sporulation and alkaline protease synthesis. We have now examined the physiological role of Sin in sporulation and found that this protein specifically represses three stage II sporulation genes (spoIIA, spoIIE, and spoIIG) but not the earlier-acting stage 0 sporulation genes. sin loss-of-function mutations cause higher expression of stage II genes and result in a higher frequency of sporulation, in general. Sin binds to the upstream promoter region of spoIIA in vitro and may thus gate entry into sporulation by directly repressing the transcription of stage II genes. In vivo levels of Sin increase rather than decrease at the time of stage II gene induction, suggesting that posttranslational modification may play a role in downregulation of negative Sin function.
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Affiliation(s)
- I Mandic-Mulec
- Department of Microbiology, New York University School of Medicine, New York 10016
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