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Scribani-Rossi C, Molina-Henares MA, Espinosa-Urgel M, Rinaldo S. Exploring the Metabolic Response of Pseudomonas putida to L-arginine. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024. [PMID: 38429473 DOI: 10.1007/5584_2024_797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/03/2024]
Abstract
Beyond their role as protein-building units, amino acids are modulators of multiple behaviours in different microorganisms. In the root-colonizing beneficial bacterium Pseudomonas putida (recently proposed to be reclassified as alloputida) KT2440, current evidence suggests that arginine functions both as a metabolic indicator and as an environmental signal molecule, modulating processes such as chemotactic responses, siderophore-mediated iron uptake or the levels of the intracellular second messenger cyclic diguanylate (c-di-GMP). Using microcalorimetry and extracellular flux analysis, in this work we have studied the metabolic adaptation of P. putida KT2440 to the presence of L-arginine in the growth medium, and the influence of mutations related to arginine metabolism. Arginine causes rapid changes in the respiratory activity of P. putida, particularly magnified in a mutant lacking the transcriptional regulator ArgR. The metabolic activity of mutants affected in arginine transport and metabolism is also altered during biofilm formation in the presence of the amino acid. The results obtained here further support the role of arginine as a metabolic signal in P. putida and the relevance of ArgR in the adaptation to the amino acid. They also serve as proof of concept on the use of calorimetric and extracellular flux techniques to analyse metabolic responses in bacteria and the impact of different mutant backgrounds on such responses.
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Affiliation(s)
- Chiara Scribani-Rossi
- Laboratory affiliated to Istituto Pasteur Italia, Fondazione Cenci Bolognetti, Department of Biochemical Sciences "A. Rossi Fanelli", Sapienza University of Rome, Rome, Italy
| | - María Antonia Molina-Henares
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidin, CSIC, Granada, Spain
| | - Manuel Espinosa-Urgel
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidin, CSIC, Granada, Spain.
| | - Serena Rinaldo
- Laboratory affiliated to Istituto Pasteur Italia, Fondazione Cenci Bolognetti, Department of Biochemical Sciences "A. Rossi Fanelli", Sapienza University of Rome, Rome, Italy.
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Molina-Henares MA, Ramos-González MI, Rinaldo S, Espinosa-Urgel M. Gene expression reprogramming of Pseudomonas alloputida in response to arginine through the transcriptional regulator ArgR. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001449. [PMID: 38511653 PMCID: PMC10963909 DOI: 10.1099/mic.0.001449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 03/07/2024] [Indexed: 03/22/2024]
Abstract
Different bacteria change their life styles in response to specific amino acids. In Pseudomonas putida (now alloputida) KT2440, arginine acts both as an environmental and a metabolic indicator that modulates the turnover of the intracellular second messenger c-di-GMP, and expression of biofilm-related genes. The transcriptional regulator ArgR, belonging to the AraC/XylS family, is key for the physiological reprogramming in response to arginine, as it controls transport and metabolism of the amino acid. To further expand our knowledge on the roles of ArgR, a global transcriptomic analysis of KT2440 and a null argR mutant growing in the presence of arginine was carried out. Results indicate that this transcriptional regulator influences a variety of cellular functions beyond arginine metabolism and transport, thus widening its regulatory role. ArgR acts as positive or negative modulator of the expression of several metabolic routes and transport systems, respiratory chain and stress response elements, as well as biofilm-related functions. The partial overlap between the ArgR regulon and those corresponding to the global regulators RoxR and ANR is also discussed.
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Affiliation(s)
- María Antonia Molina-Henares
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, CSIC. Profesor Albareda, 1. Granada 18008, Spain
| | - María Isabel Ramos-González
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, CSIC. Profesor Albareda, 1. Granada 18008, Spain
| | - Serena Rinaldo
- Laboratory Affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti - Department of Biochemical Sciences “A. Rossi Fanelli”, Sapienza University of Rome, Rome, Italy
| | - Manuel Espinosa-Urgel
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, CSIC. Profesor Albareda, 1. Granada 18008, Spain
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Zhao ZM, Meng X, Pu Y, Li M, Li Y, Zhang Y, Chen F, Ragauskas AJ. Bioconversion of Homogeneous Linear C-Lignin to Polyhydroxyalkanoates. Biomacromolecules 2023; 24:3996-4004. [PMID: 37555845 DOI: 10.1021/acs.biomac.3c00288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
The bioconversion of homogeneous linear catechyl lignin (C-lignin) to polyhydroxyalkanoates (PHA) was examined for the first time in this study. C-lignins from vanilla, euphorbia, and candlenut seed coats (denoted as C1, C2, and C3, respectively) varied in their molecular structures, which showed different molecular weight distributions, etherification degrees, and contents of hydroxyl groups. A notable amount of nonetherified catechol units existed within C1 and C2 lignins, and these catechol units were consumed during fermentation. These results suggested that the nonetherified catechol structure was readily converted by Pseudomonas putida KT2440. Since the weight-average molecular weight of C2 raw lignin was 26.7% lower than that of C1, the bioconversion performance of C2 lignin was more outstanding. The P. putida KT2440 cell amount reached the maximum of 9.3 × 107 CFU/mL in the C2 medium, which was 37.9 and 82.4% higher than that in the C1 and C3 medium, respectively. Accordingly, PHA concentration reached 137 mg/L within the C2 medium, which was 41.2 and 149.1% higher than the C1 and C3 medium, respectively. Overall, C-lignin, with a nonetherified catechol structure and low molecular weight, benefits its microbial conversion significantly.
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Affiliation(s)
- Zhi-Min Zhao
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau (Ministry of Education), School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Xianzhi Meng
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Yunqiao Pu
- Center for Bioenergy Innovation (CBI), Joint Institute of Biological Science, Biosciences Division, Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee 37831, United States
| | - Mi Li
- Department of Forestry, Wildlife, and Fisheries, Center for Renewable Carbon, University of Tennessee Institute of Agriculture, Knoxville, Tennessee 37996, United States
| | - Yibing Li
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau (Ministry of Education), School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China
| | - Yihan Zhang
- Key Laboratory of Ecology and Resource Use of the Mongolian Plateau (Ministry of Education), School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China
| | - Fang Chen
- Center for Bioenergy Innovation (CBI), Joint Institute of Biological Science, Biosciences Division, Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee 37831, United States
- BioDiscovery Institute and Department of Biological Sciences, University of North Texas, Denton, Texas 76203, United States
| | - Arthur J Ragauskas
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
- Center for Bioenergy Innovation (CBI), Joint Institute of Biological Science, Biosciences Division, Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee 37831, United States
- Department of Forestry, Wildlife, and Fisheries, Center for Renewable Carbon, University of Tennessee Institute of Agriculture, Knoxville, Tennessee 37996, United States
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Espinosa-Urgel M, Ramos-González MI. Becoming settlers: Elements and mechanisms for surface colonization by Pseudomonas putida. Environ Microbiol 2023; 25:1575-1593. [PMID: 37045787 DOI: 10.1111/1462-2920.16385] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 03/31/2023] [Indexed: 04/14/2023]
Abstract
Pseudomonads are considered to be among the most widespread culturable bacteria in mesophilic environments. The evolutive success of Pseudomonas species can be attributed to their metabolic versatility, in combination with a set of additional functions that enhance their ability to colonize different niches. These include the production of secondary metabolites involved in iron acquisition or having a detrimental effect on potential competitors, different types of motility, and the capacity to establish and persist within biofilms. Although biofilm formation has been extensively studied using the opportunistic pathogen Pseudomonas aeruginosa as a model organism, a significant body of knowledge is also becoming available for non-pathogenic Pseudomonas. In this review, we focus on the mechanisms that allow Pseudomonas putida to colonize biotic and abiotic surfaces and adapt to sessile life, as a relevant persistence strategy in the environment. This species is of particular interest because it includes plant-beneficial strains, in which colonization of plant surfaces may be relevant, and strains used for environmental and biotechnological applications, where the design and functionality of biofilm-based bioreactors, for example, also have to take into account the efficiency of bacterial colonization of solid surfaces. This work reviews the current knowledge of mechanistic and regulatory aspects of biofilm formation by P. putida and pinpoints the prospects in this field.
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Affiliation(s)
- Manuel Espinosa-Urgel
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, Granada, Spain
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Wu D, Zhao B, Zhang P, An Q. Insight into the effect of nitrate on AGS granulation: Granular characteristics, microbial community and metabolomics response. WATER RESEARCH 2023; 236:119949. [PMID: 37054606 DOI: 10.1016/j.watres.2023.119949] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 04/04/2023] [Accepted: 04/06/2023] [Indexed: 06/19/2023]
Abstract
As a promising wastewater treatment technology, aerobic granular sludge (AGS) process is still hindered by slow granule formation and easy disintegration in the application. While nitrate, one of the target pollutants in wastewater, showed a potential effect on AGS granulation process. Herein, this study attempted to reveal the role of nitrate in AGS granulation. By adding exogenous nitrate (10 mg L-1), the AGS formation was markedly improved and accomplished at 63 d, while the control group achieved AGS formation at 87 d. However, a disintegration was observed under a long-term nitrate feeding. A positive correlation was observed among granule size, extracellular polymeric substances (EPS) and intracellular c-di-GMP level in both formation and disintegration phases. The subsequent static biofilm assays indicated that nitrate might upregulate c-di-GMP via denitrification-derived NO, and c-di-GMP further upregulated EPS, thereby promoting AGS formation. However, excessive NO probably caused disintegration by downregulating c-di-GMP and EPS. Microbial community showed that nitrate favored the enrichment of denitrifiers and EPS producing microbes, which were responsible for the regulation of NO, c-di-GMP and EPS. Metabolomics analysis showed that amino acid metabolism was the most affected metabolism by nitrate. Some amino acids, such as Arg, His and Asp, were upregulated in the granule formation phase and downregulated in the disintegration phase, indicating the potential contribution to EPS biosynthesis. This study provides metabolic insight into how nitrate promotes/inhibits granulation, which may contribute to unwrapping the mystery of granulation and overcoming the limitations of AGS application.
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Affiliation(s)
- Danqing Wu
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, 400045 Chongqing, China; College of Environment and Ecology, Chongqing University, 400045 Chongqing, China
| | - Bin Zhao
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, 400045 Chongqing, China; College of Environment and Ecology, Chongqing University, 400045 Chongqing, China.
| | - Peng Zhang
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, 400045 Chongqing, China; College of Environment and Ecology, Chongqing University, 400045 Chongqing, China
| | - Qiang An
- Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, 400045 Chongqing, China; College of Environment and Ecology, Chongqing University, 400045 Chongqing, China
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Scribani-Rossi C, Molina-Henares MA, Angeli S, Cutruzzolà F, Paiardini A, Espinosa-Urgel M, Rinaldo S. The phosphodiesterase RmcA contributes to the adaptation of Pseudomonas putida to l-arginine. FEMS Microbiol Lett 2023; 370:fnad077. [PMID: 37550221 PMCID: PMC10423028 DOI: 10.1093/femsle/fnad077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 06/19/2023] [Accepted: 07/27/2023] [Indexed: 08/09/2023] Open
Abstract
Amino acids are crucial in nitrogen cycling and to shape the metabolism of microorganisms. Among them, arginine is a versatile molecule able to sustain nitrogen, carbon, and even ATP supply and to regulate multicellular behaviors such as biofilm formation. Arginine modulates the intracellular levels of 3'-5'cyclic diguanylic acid (c-di-GMP), a second messenger that controls biofilm formation, maintenance and dispersion. In Pseudomonas putida, KT2440, a versatile microorganism with wide biotechnological applications, modulation of c-di-GMP levels by arginine requires the transcriptional regulator ArgR, but the connections between arginine metabolism and c-di-GMP are not fully characterized. It has been recently demonstrated that arginine can be perceived by the opportunistic human pathogen Pseudomonas aeruginosa through the transducer RmcA protein (Redox regulator of c-di-GMP), which can directly decrease c-di-GMP levels and possibly affect biofilm architecture. A RmcA homolog is present in P. putida, but its function and involvement in arginine perceiving or biofilm life cycle had not been studied. Here, we present a preliminary characterization of the RmcA-dependent response to arginine in P. putida in modulating biofilm formation, c-di-GMP levels, and energy metabolism. This work contributes to further understanding the molecular mechanisms linking biofilm homeostasis and environmental adaptation.
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Affiliation(s)
- Chiara Scribani-Rossi
- Laboratory affiliated to Istituto Pasteur Italia, Fondazione Cenci Bolognetti, Department of Biochemical Sciences “A. Rossi Fanelli”, Sapienza University of Rome, P.le Aldo Moro 5, 00185, Rome, Italy
| | - María Antonia Molina-Henares
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidin
, CSIC, Profesor Albareda, 1, Granada, 18008, Spain
| | - Simone Angeli
- Laboratory affiliated to Istituto Pasteur Italia, Fondazione Cenci Bolognetti, Department of Biochemical Sciences “A. Rossi Fanelli”, Sapienza University of Rome, P.le Aldo Moro 5, 00185, Rome, Italy
| | - Francesca Cutruzzolà
- Laboratory affiliated to Istituto Pasteur Italia, Fondazione Cenci Bolognetti, Department of Biochemical Sciences “A. Rossi Fanelli”, Sapienza University of Rome, P.le Aldo Moro 5, 00185, Rome, Italy
| | - Alessandro Paiardini
- Laboratory affiliated to Istituto Pasteur Italia, Fondazione Cenci Bolognetti, Department of Biochemical Sciences “A. Rossi Fanelli”, Sapienza University of Rome, P.le Aldo Moro 5, 00185, Rome, Italy
| | - Manuel Espinosa-Urgel
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidin
, CSIC, Profesor Albareda, 1, Granada, 18008, Spain
| | - Serena Rinaldo
- Laboratory affiliated to Istituto Pasteur Italia, Fondazione Cenci Bolognetti, Department of Biochemical Sciences “A. Rossi Fanelli”, Sapienza University of Rome, P.le Aldo Moro 5, 00185, Rome, Italy
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Yao D, Wang X, Ma L, Wu M, Xu L, Yu Q, Zhang L, Zheng X. Impact of Weissella cibaria BYL4.2 and its supernatants on Penicillium chrysogenum metabolism. Front Microbiol 2022; 13:983613. [PMID: 36274712 PMCID: PMC9581191 DOI: 10.3389/fmicb.2022.983613] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 09/20/2022] [Indexed: 11/21/2022] Open
Abstract
Lactic acid bacteria (LAB) can produce a vast spectrum of antifungal metabolites to inhibit fungal growth. The purpose of this study was to elucidate the antifungal effect of isolated Weissella cibaria BYL4.2 on Penicillium chrysogenum, the antifungal activity of W. cibaria BYL4.2 against P. chrysogenum was evaluated by the superposition method, results showed that it had obviously antifungal activity against P. chrysogenum. Studying the probiotic properties of BYL4.2 and determining it as beneficial bacteria. Furtherly, different treatments were carried out to characterize the antifungal activity of cell-free supernatant (CFS) produced by W. cibaria BYL4.2, and it was shown that the CFS was pH-dependent, partly heat-sensitive, and was not influenced by proteinaceous treatment. The CFS of W. cibaria BYL4.2 was analyzed by high-performance liquid chromatography (HPLC) and found the highest content of lactic acid. Screening of metabolic markers by a non-targeted metabolomics approach based liquid chromatography-mass spectrometry (LC-MS). The results speculated that organic acid especially detected D-tartaric acid was the main antifungal substance of CFS, which could cause the down-regulation of metabolites in the ABC transporters pathway, thereby inhibiting the growth of P. chrysogenum. Therefore, this study may provide important information for the inhibitory mechanism of W. cibaria BYL4.2 on P. chrysogenum, and provide a basis for further research on the antifungal effect of Weissella.
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Abstract
Streptococcus mutans is a primary cariogenic pathogen in humans. Arginine metabolism is required for bacterial growth. In S. mutans, however, the involvement of transcription factors in regulating arginine metabolism is unclear. The purpose of this study was to investigate the function and mechanism of ArgR family transcription factors in S. mutans. Here, we identified an ArgR (arginine repressor) family transcription factor named AhrC, which negatively regulates arginine biosynthesis and biofilm formation in S. mutans. The ahrC in-frame deletion strain exhibited slow growth and significantly increased intracellular arginine content. The strain overexpressing ahrC showed reduced intracellular arginine content, decreased biofilm biomass, reduced production of water-insoluble exopolysaccharides (EPS), and different biofilm structures. Furthermore, global gene expression profiles revealed differential expression levels of 233 genes in the ahrC-deficient strain, among which genes related to arginine biosynthesis (argJ, argB, argC, argD, argF, argG, argH) were significantly upregulated. In the ahrC overexpression strain, there are 89 differentially expressed genes, mostly related to arginine biosynthesis. The conserved DNA patterns bound by AhrC were identified by electrophoretic mobility shift assay (EMSA) and DNase I footprinting. In addition, the analysis of β-galactosidase activity showed that AhrC acted as a negative regulator. Taken together, our findings suggest that AhrC is an important transcription factor that regulates arginine biosynthesis gene expression and biofilm formation in S. mutans. These findings add new aspects to the complexity of regulating the expression of genes involved in arginine biosynthesis and biofilm formation in S. mutans. IMPORTANCE Arginine metabolism is essential for bacterial growth. The regulation of intracellular arginine metabolism in Streptococcus mutans, one of the major pathogens of dental caries, is unclear. In this study, we found that the transcription factor AhrC can directly and negatively regulate the expression of N-acetyl-gamma-glutamyl-phosphate reductase (argC), thus regulating arginine biosynthesis in S. mutans. In addition, the ahrC overexpression strain exhibited a significant decrease in biofilm and water-insoluble extracellular polysaccharides (EPS). This study adds new support to our understanding of the regulation of intracellular arginine metabolism in S. mutans.
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Sharma G, Curtis PD. The Impacts of Microgravity on Bacterial Metabolism. Life (Basel) 2022; 12:life12060774. [PMID: 35743807 PMCID: PMC9225508 DOI: 10.3390/life12060774] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/18/2022] [Accepted: 05/20/2022] [Indexed: 12/15/2022] Open
Abstract
The inside of a space-faring vehicle provides a set of conditions unlike anything experienced by bacteria on Earth. The low-shear, diffusion-limited microenvironment with accompanying high levels of ionizing radiation create high stress in bacterial cells, and results in many physiological adaptations. This review gives an overview of the effect spaceflight in general, and real or simulated microgravity in particular, has on primary and secondary metabolism. Some broad trends in primary metabolic responses can be identified. These include increases in carbohydrate metabolism, changes in carbon substrate utilization range, and changes in amino acid metabolism that reflect increased oxidative stress. However, another important trend is that there is no universal bacterial response to microgravity, as different bacteria often have contradictory responses to the same stress. This is exemplified in many of the observed secondary metabolite responses where secondary metabolites may have increased, decreased, or unchanged production in microgravity. Different secondary metabolites in the same organism can even show drastically different production responses. Microgravity can also impact the production profile and localization of secondary metabolites. The inconsistency of bacterial responses to real or simulated microgravity underscores the importance of further research in this area to better understand how microbes can impact the people and systems aboard spacecraft.
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Nutrient Sensing and Biofilm Modulation: The Example of L-arginine in Pseudomonas. Int J Mol Sci 2022; 23:ijms23084386. [PMID: 35457206 PMCID: PMC9028604 DOI: 10.3390/ijms23084386] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 04/12/2022] [Accepted: 04/13/2022] [Indexed: 12/01/2022] Open
Abstract
Bacterial biofilm represents a multicellular community embedded within an extracellular matrix attached to a surface. This lifestyle confers to bacterial cells protection against hostile environments, such as antibiotic treatment and host immune response in case of infections. The Pseudomonas genus is characterised by species producing strong biofilms difficult to be eradicated and by an extraordinary metabolic versatility which may support energy and carbon/nitrogen assimilation under multiple environmental conditions. Nutrient availability can be perceived by a Pseudomonas biofilm which, in turn, readapts its metabolism to finally tune its own formation and dispersion. A growing number of papers is now focusing on the mechanism of nutrient perception as a possible strategy to weaken the biofilm barrier by environmental cues. One of the most important nutrients is amino acid L-arginine, a crucial metabolite sustaining bacterial growth both as a carbon and a nitrogen source. Under low-oxygen conditions, L-arginine may also serve for ATP production, thus allowing bacteria to survive in anaerobic environments. L-arginine has been associated with biofilms, virulence, and antibiotic resistance. L-arginine is also a key precursor of regulatory molecules such as polyamines, whose involvement in biofilm homeostasis is reported. Given the biomedical and biotechnological relevance of biofilm control, the state of the art on the effects mediated by the L-arginine nutrient on biofilm modulation is presented, with a special focus on the Pseudomonas biofilm. Possible biotechnological and biomedical applications are also discussed.
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Biofilm Maintenance as an Active Process: Evidence that Biofilms Work Hard to Stay Put. J Bacteriol 2022; 204:e0058721. [PMID: 35311557 DOI: 10.1128/jb.00587-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Biofilm formation represents a critical strategy whereby bacteria can tolerate otherwise damaging environmental stressors and antimicrobial insults. While the mechanisms bacteria use to establish a biofilm and disperse from these communities have been well-studied, we have only a limited understanding of the mechanisms required to maintain these multicellular communities. Indeed, until relatively recently, it was not clear that maintaining a mature biofilm could be considered an active, regulated process with dedicated machinery. Using Pseudomonas aeruginosa as a model system, we review evidence from recent studies that support the model that maintenance of these persistent, surface-attached communities is indeed an active process. Biofilm maintenance mechanisms include transcriptional regulation and second messenger signaling (including the production of extracellular polymeric substances). We also discuss energy-conserving pathways that play a key role in the maintenance of these communities. We hope to highlight the need for further investigation to uncover novel biofilm maintenance pathways and suggest the possibility that such pathways can serve as novel antibiofilm targets.
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Role of the Transcriptional Regulator ArgR in the Connection between Arginine Metabolism and c-di-GMP Signaling in Pseudomonas putida. Appl Environ Microbiol 2022; 88:e0006422. [PMID: 35254100 DOI: 10.1128/aem.00064-22] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The second messenger cyclic di-GMP (c-di-GMP) is a key molecule that controls different physiological and behavioral processes in many bacteria, including motile-to-sessile lifestyle transitions. Although the external stimuli that modulate cellular c-di-GMP contents are not fully characterized, there is growing evidence that certain amino acids act as environmental cues for c-di-GMP turnover. In the plant-beneficial bacterium Pseudomonas putida KT2440, both arginine biosynthesis and uptake influence second messenger contents and the associated phenotypes. To further understand this connection, we have analyzed the role of ArgR, which in different bacteria is the master transcriptional regulator of arginine metabolism but had not been characterized in P. putida. The results show that ArgR controls arginine biosynthesis and transport, and an argR-null mutant grows poorly with arginine as the sole carbon or nitrogen source and also displays increased biofilm formation and reduced surface motility. Modulation of c-di-GMP levels by exogenous arginine requires ArgR. The expression of certain biofilm matrix components, namely, the adhesin LapF and the exopolysaccharide Pea, as well as the diguanylate cyclase CfcR is influenced by ArgR, likely through the alternative sigma factor RpoS. Our data indicate the existence of a regulatory feedback loop between ArgR and c-di-GMP mediated by FleQ. IMPORTANCE Identifying the molecular mechanisms by which metabolic and environmental signals influence the turnover of the second messenger c-di-GMP is key to understanding the regulation of bacterial lifestyles. The results presented here point at the transcriptional regulator ArgR as a central node linking arginine metabolism and c-di-GMP signaling and indicate the existence of a complex balancing mechanism that connects cellular arginine contents and second messenger levels, ultimately controlling the lifestyles of Pseudomonas putida.
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Leggett A, Li DW, Sindeldecker D, Staats A, Rigel N, Bruschweiler-Li L, Brüschweiler R, Stoodley P. Cadaverine Is a Switch in the Lysine Degradation Pathway in Pseudomonas aeruginosa Biofilm Identified by Untargeted Metabolomics. Front Cell Infect Microbiol 2022; 12:833269. [PMID: 35237533 PMCID: PMC8884266 DOI: 10.3389/fcimb.2022.833269] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 01/18/2022] [Indexed: 12/16/2022] Open
Abstract
There is a critical need to accurately diagnose, prevent, and treat biofilms in humans. The biofilm forming P. aeruginosa bacteria can cause acute and chronic infections, which are difficult to treat due to their ability to evade host defenses along with an inherent antibiotic-tolerance. Using an untargeted NMR-based metabolomics approach, we identified statistically significant differences in 52 metabolites between P. aeruginosa grown in the planktonic and lawn biofilm states. Among them, the metabolites of the cadaverine branch of the lysine degradation pathway were systematically decreased in biofilm. Exogenous supplementation of cadaverine caused significantly increased planktonic growth, decreased biofilm accumulation by 49% and led to altered biofilm morphology, converting to a pellicle biofilm at the air-liquid interface. Our findings show how metabolic pathway differences directly affect the growth mode in P. aeruginosa and could support interventional strategies to control biofilm formation.
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Affiliation(s)
- Abigail Leggett
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, United States
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, United States
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, United States
| | - Da-Wei Li
- Campus Chemical Instrument Center, The Ohio State University, Columbus, OH, United States
| | - Devin Sindeldecker
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, United States
- Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH, United States
| | - Amelia Staats
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, United States
- Department of Microbiology, The Ohio State University, Columbus, OH, United States
| | - Nicholas Rigel
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, United States
| | - Lei Bruschweiler-Li
- Campus Chemical Instrument Center, The Ohio State University, Columbus, OH, United States
| | - Rafael Brüschweiler
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, United States
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, United States
- Campus Chemical Instrument Center, The Ohio State University, Columbus, OH, United States
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, United States
- *Correspondence: Rafael Brüschweiler, ; Paul Stoodley,
| | - Paul Stoodley
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, United States
- Department of Microbiology, The Ohio State University, Columbus, OH, United States
- Department of Orthopaedics, The Ohio State University, Columbus, OH, United States
- National Biofilm Innovation Centre (NBIC) and National Centre for Advanced Tribology at Southampton (nCATS), Mechanical Engineering, University of Southampton, Southampton, United Kingdom
- *Correspondence: Rafael Brüschweiler, ; Paul Stoodley,
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14
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Park S, Sauer K. Controlling Biofilm Development Through Cyclic di-GMP Signaling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1386:69-94. [PMID: 36258069 PMCID: PMC9891824 DOI: 10.1007/978-3-031-08491-1_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The cyclic di-GMP (c-di-GMP) second messenger represents a signaling system that regulates many bacterial behaviors and is of key importance for driving the lifestyle switch between motile loner cells and biofilm formers. This review provides an up-to-date summary of c-di-GMP pathways connected to biofilm formation by the opportunistic pathogen P. aeruginosa. Emphasis will be on the timing of c-di-GMP production over the course of biofilm formation, to highlight non-uniform and hierarchical increases in c-di-GMP levels, as well as biofilm growth conditions that do not conform with our current model of c-di-GMP.
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Affiliation(s)
- Soyoung Park
- Department of Biological Sciences, Binghamton University, Binghamton, NY, USA
- Binghamton Biofilm Research Center (BBRC), Binghamton University, Binghamton, NY, USA
| | - Karin Sauer
- Department of Biological Sciences, Binghamton University, Binghamton, NY, USA.
- Binghamton Biofilm Research Center (BBRC), Binghamton University, Binghamton, NY, USA.
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15
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Putrescine and its metabolic precursor arginine promote biofilm and c-di-GMP synthesis in Pseudomonas aeruginosa. J Bacteriol 2021; 204:e0029721. [PMID: 34723645 DOI: 10.1128/jb.00297-21] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa, an opportunistic bacterial pathogen can synthesize and catabolize a number of small cationic molecules known as polyamines. In several clades of bacteria polyamines regulate biofilm formation, a lifestyle-switching process that confers resistance to environmental stress. The polyamine putrescine and its biosynthetic precursors, L-arginine and agmatine, promote biofilm formation in Pseudomonas spp. However, it remains unclear whether the effect is a direct effect of polyamines or through a metabolic derivative. Here we used a genetic approach to demonstrate that putrescine accumulation, either through disruption of the spermidine biosynthesis pathway or the catabolic putrescine aminotransferase pathway, promoted biofilm formation in P. aeruginosa. Consistent with this observation, exogenous putrescine robustly induced biofilm formation in P. aeruginosa that was dependent on putrescine uptake and biosynthesis pathways. Additionally, we show that L-arginine, the biosynthetic precursor of putrescine, also promoted biofilm formation, but via a mechanism independent of putrescine or agmatine conversion. We found that both putrescine and L-arginine induced a significant increase in the intracellular level of bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) (c-di-GMP), a bacterial second messenger widely found in Proteobacteria that upregulates biofilm formation. Collectively these data show that putrescine and its metabolic precursor arginine promote biofilm and c-di-GMP synthesis in P. aeruginosa. Importance: Biofilm formation allows bacteria to physically attach to a surface, confers tolerance to antimicrobial agents, and promotes resistance to host immune responses. As a result, regulation of biofilm is often crucial for bacterial pathogens to establish chronic infections. A primary mechanism of biofilm promotion in bacteria is the molecule c-di-GMP, which promotes biofilm formation. The level of c-di-GMP is tightly regulated by bacterial enzymes. In this study, we found that putrescine, a small molecule ubiquitously found in eukaryotic cells, robustly enhances P. aeruginosa biofilm and c-di-GMP. We propose that P. aeruginosa may sense putrescine as a host-associated signal that triggers a lifestyle switching that favors chronic infection.
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16
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Pulukkody AC, Yung YP, Donnarumma F, Murray KK, Carlson RP, Hanley L. Spatially resolved analysis of Pseudomonas aeruginosa biofilm proteomes measured by laser ablation sample transfer. PLoS One 2021; 16:e0250911. [PMID: 34292966 PMCID: PMC8297752 DOI: 10.1371/journal.pone.0250911] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 06/22/2021] [Indexed: 12/18/2022] Open
Abstract
Heterogeneity in the distribution of nutrients and oxygen gradients during biofilm growth gives rise to changes in phenotype. There has been long term interest in identifying spatial differences during biofilm development including clues that identify chemical heterogeneity. Laser ablation sample transfer (LAST) allows site-specific sampling combined with label free proteomics to distinguish radially and axially resolved proteomes for Pseudomonas aeruginosa biofilms. Specifically, differential protein abundances on oxic vs. anoxic regions of a biofilm were observed by combining LAST with bottom up proteomics. This study reveals a more active metabolism in the anoxic region of the biofilm with respect to the oxic region for this clinical strain of P. aeruginosa, despite this organism being considered an aerobe by nature. Protein abundance data related to cellular acclimations to chemical gradients include identification of glucose catabolizing proteins, high abundance of proteins from arginine and polyamine metabolism, and proteins that could also support virulence and environmental stress mediation in the anoxic region. Finally, the LAST methodology requires only a few mm2 of biofilm area to identify hundreds of proteins.
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Affiliation(s)
- Aruni Chathurya Pulukkody
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Yeni P. Yung
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Fabrizio Donnarumma
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Kermit K. Murray
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Ross P. Carlson
- Department of Chemical and Biological Engineering, Center for Biofilm Engineering, Montana State University, Bozeman, Montana, United States of America
| | - Luke Hanley
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois, United States of America
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17
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Chen X, Hu Y, Tian S, Han B. Understanding the Interactions between Staphylococcus aureus and the Raw-Meat-Processing Environment Isolate Klebsiella oxytoca in Dual-Species Biofilms via Discovering an Altered Metabolic Profile. Microorganisms 2021; 9:microorganisms9040672. [PMID: 33805148 PMCID: PMC8064066 DOI: 10.3390/microorganisms9040672] [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: 02/10/2021] [Revised: 03/02/2021] [Accepted: 03/23/2021] [Indexed: 11/24/2022] Open
Abstract
In a raw-meat-processing environment, members of the Enterobacteriaceae family can coexist with Staphylococcus aureus to form dual-species biofilms, leading to a higher risk of food contamination. However, very little is known about the effect of inter-species interactions on dual-species biofilm formation. The aim of this study was to investigate the interactions between S. aureus and raw-meat-processing environment isolates of Klebsiella oxytoca in dual-species biofilms, by employing an untargeted metabolomics tool. Crystal violet staining assay showed that the biomass of the dual-species biofilm significantly increased and reached its maximum after incubation for 21 h, compared with that of single species grown alone. The number of K. oxytoca in the dual-species biofilm was significantly higher than that of S. aureus. Field emission scanning electron microscopy (FESEM) revealed that both species were evenly distributed, and were tightly wrapped by extracellular polymeric substances in the dual-species biofilms. Ultra-high-pressure liquid chromatography equipped with a quadrupole-time-of-flight mass spectrometer (UHPLC-Q-TOF MS) analysis exhibited a total of 8184 positive ions, and 6294 negative ions were obtained from all test samples. Multivariate data analysis further described altered metabolic profiling between mono- and dual-species biofilms. Further, 18 and 21 different metabolites in the dual-species biofilm were screened as biomarkers by comparing the mono-species biofilms of S. aureus and K. oxytoca, respectively. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways that were exclusively upregulated in the dual-species biofilm included ABC transporters, amino acid metabolism, and the two-component signal transduction system. Our results contribute to a better understanding of the interactive behavior of inter-species biofilm communities, by discovering altered metabolic profiling.
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18
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Ruiz A, Herráez M, Costa-Gutierrez SB, Molina-Henares MA, Martínez MJ, Espinosa-Urgel M, Barriuso J. The architecture of a mixed fungal-bacterial biofilm is modulated by quorum-sensing signals. Environ Microbiol 2021; 23:2433-2447. [PMID: 33615654 DOI: 10.1111/1462-2920.15444] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/16/2021] [Accepted: 02/20/2021] [Indexed: 11/26/2022]
Abstract
Interkingdom communication is of particular relevance in polymicrobial biofilms. In this work, the ability of the fungus Ophiostoma piceae to form biofilms individually and in consortium with the bacterium Pseudomonas putida, as well as the effect of fungal and bacterial signal molecules on the architecture of the biofilms was evaluated. Pseudomonas putida KT2440 is able to form biofilms through the secretion of exopolysaccharides and two large extracellular adhesion proteins, LapA and LapF. It has two intercellular signalling systems, one mediated by dodecanoic acid and an orphan LuxR receptor that could participate in the response to AHL-type quorum sensing molecules (QSMs). Furthermore, the dimorphic fungus O. piceae uses farnesol as QSM to control its yeast to hyphae morphological transition. Results show for the first time the ability of this fungus to form biofilms alone and in mixed cultures with the bacterium. Biofilms were induced by bacterial and fungal QSMs. The essential role of LapA-LapF proteins in the architecture of biofilms was corroborated, LapA was induced by farnesol and dodecanol, while LapF by 3-oxo-C6-HSL and 3-oxo-C12-HSL. Our results indicate that fungal signals can induce a transient rise in the levels of the secondary messenger c-di-GMP, which control biofilm formation and architecture.
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Affiliation(s)
- Alberto Ruiz
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CIB-CSIC), C/Ramiro de Maeztu 9, Madrid, 28040, Spain
| | - Marta Herráez
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CIB-CSIC), C/Ramiro de Maeztu 9, Madrid, 28040, Spain
| | - Stefanie B Costa-Gutierrez
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (EEZ-CSIC), C/Profesor Albareda 1, Granada, 18008, Spain
| | - María Antonia Molina-Henares
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (EEZ-CSIC), C/Profesor Albareda 1, Granada, 18008, Spain
| | - María Jesús Martínez
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CIB-CSIC), C/Ramiro de Maeztu 9, Madrid, 28040, Spain
| | - Manuel Espinosa-Urgel
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (EEZ-CSIC), C/Profesor Albareda 1, Granada, 18008, Spain
| | - Jorge Barriuso
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CIB-CSIC), C/Ramiro de Maeztu 9, Madrid, 28040, Spain
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19
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Huertas-Rosales Ó, Romero M, Chan KG, Hong KW, Cámara M, Heeb S, Barrientos-Moreno L, Molina-Henares MA, Travieso ML, Ramos-González MI, Espinosa-Urgel M. Genome-Wide Analysis of Targets for Post-Transcriptional Regulation by Rsm Proteins in Pseudomonas putida. Front Mol Biosci 2021; 8:624061. [PMID: 33693029 PMCID: PMC7937890 DOI: 10.3389/fmolb.2021.624061] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 01/21/2021] [Indexed: 12/31/2022] Open
Abstract
Post-transcriptional regulation is an important step in the control of bacterial gene expression in response to environmental and cellular signals. Pseudomonas putida KT2440 harbors three known members of the CsrA/RsmA family of post-transcriptional regulators: RsmA, RsmE and RsmI. We have carried out a global analysis to identify RNA sequences bound in vivo by each of these proteins. Affinity purification and sequencing of RNA molecules associated with Rsm proteins were used to discover direct binding targets, corresponding to 437 unique RNA molecules, 75 of them being common to the three proteins. Relevant targets include genes encoding proteins involved in signal transduction and regulation, metabolism, transport and secretion, stress responses, and the turnover of the intracellular second messenger c-di-GMP. To our knowledge, this is the first combined global analysis in a bacterium harboring three Rsm homologs. It offers a broad overview of the network of processes subjected to this type of regulation and opens the way to define what are the sequence and structure determinants that define common or differential recognition of specific RNA molecules by these proteins.
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Affiliation(s)
- Óscar Huertas-Rosales
- Department of Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain
| | - Manuel Romero
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Kok-Gan Chan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.,International Genome Centre, Jiangsu University, Zhenjiang, China
| | - Kar-Wai Hong
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.,International Genome Centre, Jiangsu University, Zhenjiang, China
| | - Miguel Cámara
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Stephan Heeb
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Laura Barrientos-Moreno
- Department of Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain.,National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | | | - María L Travieso
- Department of Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain
| | | | - Manuel Espinosa-Urgel
- Department of Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain
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20
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Zboralski A, Filion M. Genetic factors involved in rhizosphere colonization by phytobeneficial Pseudomonas spp. Comput Struct Biotechnol J 2020; 18:3539-3554. [PMID: 33304453 PMCID: PMC7711191 DOI: 10.1016/j.csbj.2020.11.025] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 11/10/2020] [Accepted: 11/12/2020] [Indexed: 12/13/2022] Open
Abstract
Plant growth-promoting rhizobacteria (PGPR) actively colonize the soil portion under the influence of plant roots, called the rhizosphere. Many plant-beneficial Pseudomonas spp. have been characterized as PGPR. They are ubiquitous rod-shaped motile Gram-negative bacteria displaying a high metabolic versatility. Their capacity to protect plants from pathogens and improve plant growth closely depends on their rhizosphere colonization abilities. Various molecular and cellular mechanisms are involved in this complex process, such as chemotaxis, biofilm formation, secondary metabolites biosynthesis, metabolic versatility, and evasion of plant immunity. The burst in Pseudomonas spp. genome sequencing in recent years has been crucial to better understand how they colonize the rhizosphere. In this review, we discuss the recent advances regarding these mechanisms and the underlying bacterial genetic factors required for successful rhizosphere colonization.
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Affiliation(s)
- Antoine Zboralski
- Department of Biology, Université de Moncton, Moncton, NB E1A 3E9, Canada
| | - Martin Filion
- Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Jean-sur-Richelieu, QC J3B 3E6, Canada
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