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Singh CK, Sodhi KK, Shree P, Nitin V. Heavy Metals as Catalysts in the Evolution of Antimicrobial Resistance and the Mechanisms Underpinning Co-selection. Curr Microbiol 2024; 81:148. [PMID: 38642082 DOI: 10.1007/s00284-024-03648-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 02/22/2024] [Indexed: 04/22/2024]
Abstract
The menace caused by antibiotic resistance in bacteria is acknowledged on a global scale. Concerns over the same are increasing because of the selection pressure exerted by a huge number of different antimicrobial agents, including heavy metals. Heavy metals are non-metabolizable and recalcitrant to degradation, therefore the bacteria can expel the pollutants out of the system and make it less harmful via different mechanisms. The selection of antibiotic-resistant bacteria may be influenced by heavy metals present in environmental reservoirs. Through co-resistance and cross-resistance processes, the presence of heavy metals in the environment can act as co-selecting agents, hence increasing resistance to both heavy metals and antibiotics. The horizontal gene transfer or mutation assists in the selection of mutant bacteria resistant to the polluted environment. Hence, bioremediation and biodegradation are sustainable methods for the natural clean-up of pollutants. This review sheds light on the occurrence of metal and antibiotic resistance in the environment via the co-resistance and cross-resistance mechanisms underpinning co-selection emphasizing the dearth of studies that specifically examine the method of co-selection in clinical settings. Furthermore, it is advised that future research incorporate both culture- and molecular-based methodologies to further our comprehension of the mechanisms underlying bacterial co- and cross-resistance to antibiotics and heavy metals.
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Affiliation(s)
| | - Kushneet Kaur Sodhi
- Department of Zoology, Sri Guru Tegh Bahadur Khalsa College, University of Delhi, Delhi, 110007, India.
| | - Pallee Shree
- Department of Zoology, Lady Irwin College, University of Delhi, Delhi, 110001, India
| | - V Nitin
- Bhaskaracharya College of Applied Sciences, University of Delhi, Delhi, 110075, India
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2
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Gvozdev MY, Turomsha IS, Savich VV, Faletrov YV, Sidarenka AV, Shkumatov VM, Loginova NV. Sterically hindered phenolic derivatives: effect on the production of Pseudomonas aeruginosa virulence factors, high-throughput virtual screening and ADME properties prediction. Arch Microbiol 2024; 206:91. [PMID: 38316691 DOI: 10.1007/s00203-023-03827-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/13/2023] [Accepted: 12/30/2023] [Indexed: 02/07/2024]
Abstract
Inhibition of quorum sensing is considered to be an effective strategy of control and treatment of a wide range of acute and persistent infections. Pseudomonas aeruginosa is an opportunistic bacterium with a high adaptation potential that contributes to healthcare-associated infections. In the present study, the effects of the synthesized hybrid structures bearing sterically hindered phenolic and heterocyclic moieties in a single scaffold on the production of virulence factors by P. aeruginosa were determined. It has been shown that the obtained compounds significantly reduce both pyocyanin and alginate production and stimulate the biosynthesis of siderophores in vitro, which may be attributed to their iron-chelating properties. The results of docking-based inverse high-throughput virtual screening indicate that transcription regulator LasR and Cu-transporter OPRC could be potential molecular targets for these compounds. Investigation of the impact small molecules exert on the molecular mechanisms of the production of bacterial virulence factors may pave the way for the design and development of novel antibacterial agents.
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Affiliation(s)
- Maxim Y Gvozdev
- Faculty of Chemistry, Belarusian State University, Leningradskaya Str. 14, Minsk, Belarus
- Research Institute for Physical Chemical Problems, Belarusian State University, Leningradskaya Str. 14, Minsk, Belarus
| | - Iveta S Turomsha
- Faculty of Chemistry, Belarusian State University, Leningradskaya Str. 14, Minsk, Belarus
- Research Institute for Physical Chemical Problems, Belarusian State University, Leningradskaya Str. 14, Minsk, Belarus
| | - Viktoryia V Savich
- Institute of Microbiology of the National Academy of Sciences of Belarus, Minsk, Belarus
| | - Yaroslav V Faletrov
- Faculty of Chemistry, Belarusian State University, Leningradskaya Str. 14, Minsk, Belarus
- Research Institute for Physical Chemical Problems, Belarusian State University, Leningradskaya Str. 14, Minsk, Belarus
| | - Anastasiya V Sidarenka
- Institute of Microbiology of the National Academy of Sciences of Belarus, Minsk, Belarus
| | - Vladimir M Shkumatov
- Faculty of Chemistry, Belarusian State University, Leningradskaya Str. 14, Minsk, Belarus
- Research Institute for Physical Chemical Problems, Belarusian State University, Leningradskaya Str. 14, Minsk, Belarus
| | - Natalia V Loginova
- Faculty of Chemistry, Belarusian State University, Leningradskaya Str. 14, Minsk, Belarus.
- Research Institute for Physical Chemical Problems, Belarusian State University, Leningradskaya Str. 14, Minsk, Belarus.
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3
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Vats P, Kaur UJ, Rishi P. Heavy metal-induced selection and proliferation of antibiotic resistance: A review. J Appl Microbiol 2022; 132:4058-4076. [PMID: 35170159 DOI: 10.1111/jam.15492] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 12/28/2021] [Accepted: 02/11/2022] [Indexed: 11/28/2022]
Abstract
Antibiotic resistance is recognized as a global threat to public health. The selection and evolution of antibiotic resistance in clinical pathogens was believed to be majorly driven by the imprudent use of antibiotics. However, concerns regarding the same, through selection pressure by a multitude of other antimicrobial agents, such as heavy metals, are also growing. Heavy metal contamination co-selects antibiotic and metal resistance through numerous mechanisms, such as co-resistance and cross-resistance. Here, we have reviewed the role of heavy metals as antimicrobial resistance driving agents and the underlying concept and mechanisms of co-selection, while also highlighting the scarcity in studies explicitly inspecting the process of co-selection in clinical settings. Prospective strategies to manage heavy metal-induced antibiotic resistance have also been deliberated, underlining the need to find specific inhibitors so that alternate medicinal combinations can be added to the existing therapeutic armamentarium.
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Affiliation(s)
- Prakriti Vats
- Department of Microbiology, Panjab University, Chandigarh, India
| | - Ujjwal Jit Kaur
- Department of Microbiology, Panjab University, Chandigarh, India
| | - Praveen Rishi
- Department of Microbiology, Panjab University, Chandigarh, India
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O’Malley MR, Anderson JC. Regulation of the Pseudomonas syringae Type III Secretion System by Host Environment Signals. Microorganisms 2021; 9:microorganisms9061227. [PMID: 34198761 PMCID: PMC8228185 DOI: 10.3390/microorganisms9061227] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/30/2021] [Accepted: 06/01/2021] [Indexed: 12/12/2022] Open
Abstract
Pseudomonas syringae are Gram-negative, plant pathogenic bacteria that use a type III secretion system (T3SS) to disarm host immune responses and promote bacterial growth within plant tissues. Despite the critical role for type III secretion in promoting virulence, T3SS-encoding genes are not constitutively expressed by P. syringae and must instead be induced during infection. While it has been known for many years that culturing P. syringae in synthetic minimal media can induce the T3SS, relatively little is known about host signals that regulate the deployment of the T3SS during infection. The recent identification of specific plant-derived amino acids and organic acids that induce T3SS-inducing genes in P. syringae has provided new insights into host sensing mechanisms. This review summarizes current knowledge of the regulatory machinery governing T3SS deployment in P. syringae, including master regulators HrpRS and HrpL encoded within the T3SS pathogenicity island, and the environmental factors that modulate the abundance and/or activity of these key regulators. We highlight putative receptors and regulatory networks involved in linking the perception of host signals to the regulation of the core HrpRS–HrpL pathway. Positive and negative regulation of T3SS deployment is also discussed within the context of P. syringae infection, where contributions from distinct host signals and regulatory networks likely enable the fine-tuning of T3SS deployment within host tissues. Last, we propose future research directions necessary to construct a comprehensive model that (a) links the perception of host metabolite signals to T3SS deployment and (b) places these host–pathogen signaling events in the overall context of P. syringae infection.
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Luti S, Campigli S, Ranaldi F, Paoli P, Pazzagli L, Marchi G. Lscβ and lscγ, two novel levansucrases of Pseudomonas syringae pv. actinidiae biovar 3, the causal agent of bacterial canker of kiwifruit, show different enzymatic properties. Int J Biol Macromol 2021; 179:279-291. [PMID: 33675829 DOI: 10.1016/j.ijbiomac.2021.02.189] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 02/21/2021] [Accepted: 02/25/2021] [Indexed: 11/26/2022]
Abstract
Bacterial canker disease caused by Pseudomonas syringae pv. actinidiae (Psa) biovar 3 involved all global interest since 2008. We have found that in Psa3 genome, similarly to other P. syringae, there are three putative genes, lscα, lscβ and lscγ, coding for levansucrases. These enzymes, breaking the sucrose moiety and releasing glucose can synthetize the fructose polymer levan, a hexopolysaccharide that is well known to be part of the survival strategies of many different bacteria. Considering lscα non-coding because of a premature stop codon, in the present work we cloned and expressed the two putatively functional levansucrases of Psa3, lscβ and lscγ, in E. coli and characterized their biochemical properties such as optimum of pH, temperature and ionic strength. Interestingly, we found completely different behaviour for both sucrose splitting activity and levan synthesis between the two proteins; lscγ polymerizes levan quickly at pH 5.0 while lscβ has great sucrose hydrolysis activity at pH 7.0. Moreover, we demonstrated that at least in vitro conditions, they are differentially expressed suggesting two distinct roles in the physiology of the bacterium.
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Affiliation(s)
- Simone Luti
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, Italy.
| | - Sara Campigli
- Department of Agriculture, Food, Environment and Forestry, University of Florence, Italy
| | - Francesco Ranaldi
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, Italy
| | - Paolo Paoli
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, Italy
| | - Luigia Pazzagli
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, Italy
| | - Guido Marchi
- Department of Agriculture, Food, Environment and Forestry, University of Florence, Italy
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Beyond the Wall: Exopolysaccharides in the Biofilm Lifestyle of Pathogenic and Beneficial Plant-Associated Pseudomonas. Microorganisms 2021; 9:microorganisms9020445. [PMID: 33670010 PMCID: PMC7926942 DOI: 10.3390/microorganisms9020445] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/12/2021] [Accepted: 02/18/2021] [Indexed: 11/16/2022] Open
Abstract
The formation of biofilms results from a multicellular mode of growth, in which bacteria remain enwrapped by an extracellular matrix of their own production. Many different bacteria form biofilms, but among the most studied species are those that belong to the Pseudomonas genus due to the metabolic versatility, ubiquity, and ecological significance of members of this group of microorganisms. Within the Pseudomonas genus, biofilm studies have mainly focused on the opportunistic human pathogen Pseudomonas aeruginosa due to its clinical importance. The extracellular matrix of P. aeruginosa is mainly composed of exopolysaccharides, which have been shown to be important for the biofilm architecture and pathogenic features of this bacterium. Notably, some of the exopolysaccharides recurrently used by P. aeruginosa during biofilm formation, such as the alginate and polysaccharide synthesis loci (Psl) polysaccharides, are also used by pathogenic and beneficial plant-associated Pseudomonas during their interaction with plants. Interestingly, their functions are multifaceted and seem to be highly dependent on the bacterial lifestyle and genetic context of production. This paper reviews the functions and significance of the exopolysaccharides produced by plant-associated Pseudomonas, particularly the alginate, Psl, and cellulose polysaccharides, focusing on their equivalents produced in P. aeruginosa within the context of pathogenic and beneficial interactions.
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Heredia-Ponce Z, Gutiérrez-Barranquero JA, Purtschert-Montenegro G, Eberl L, Cazorla FM, de Vicente A. Biological role of EPS from Pseudomonas syringae pv. syringae UMAF0158 extracellular matrix, focusing on a Psl-like polysaccharide. NPJ Biofilms Microbiomes 2020; 6:37. [PMID: 33046713 PMCID: PMC7550585 DOI: 10.1038/s41522-020-00148-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 09/10/2020] [Indexed: 12/11/2022] Open
Abstract
Pseudomonas syringae is a phytopathogenic model bacterium that is used worldwide to study plant-bacteria interactions and biofilm formation in association with a plant host. Within this species, the syringae pathovar is the most studied due to its wide host range, affecting both, woody and herbaceous plants. In particular, Pseudomonas syringae pv. syringae (Pss) has been previously described as the causal agent of bacterial apical necrosis on mango trees. Pss exhibits major epiphytic traits and virulence factors that improve its epiphytic survival and pathogenicity in mango trees. The cellulose exopolysaccharide has been described as a key component in the development of the biofilm lifestyle of the P. syringae pv. syringae UMAF0158 strain (PssUMAF0158). PssUMAF0158 contains two additional genomic regions that putatively encode for exopolysaccharides such as alginate and a Psl-like polysaccharide. To date, the Psl polysaccharide has only been studied in Pseudomonas aeruginosa, in which it plays an important role during biofilm development. However, its function in plant-associated bacteria is still unknown. To understand how these exopolysaccharides contribute to the biofilm matrix of PssUMAF0158, knockout mutants of genes encoding these putative exopolysaccharides were constructed. Flow-cell chamber experiments revealed that cellulose and the Psl-like polysaccharide constitute a basic scaffold for biofilm architecture in this bacterium. Curiously, the Psl-like polysaccharide of PssUMAF0158 plays a role in virulence similar to what has been described for cellulose. Finally, the impaired swarming motility of the Psl-like exopolysaccharide mutant suggests that this exopolysaccharide may play a role in the motility of PssUMAF0158 over the mango plant surface.
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Affiliation(s)
- Zaira Heredia-Ponce
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM-UMA-CSIC) - Departamento de Microbiología, Universidad de Málaga, Bulevar Louis Pasteur, 31 (Campus Universitario de Teatinos), 29071, Málaga, Spain
| | - Jose Antonio Gutiérrez-Barranquero
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM-UMA-CSIC) - Departamento de Microbiología, Universidad de Málaga, Bulevar Louis Pasteur, 31 (Campus Universitario de Teatinos), 29071, Málaga, Spain
| | | | - Leo Eberl
- Department of Plant and Microbial Biology, University of Zurich. Zollikerstrasse 107, CH-8008, Zurich, Switzerland
| | - Francisco M Cazorla
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM-UMA-CSIC) - Departamento de Microbiología, Universidad de Málaga, Bulevar Louis Pasteur, 31 (Campus Universitario de Teatinos), 29071, Málaga, Spain
| | - Antonio de Vicente
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM-UMA-CSIC) - Departamento de Microbiología, Universidad de Málaga, Bulevar Louis Pasteur, 31 (Campus Universitario de Teatinos), 29071, Málaga, Spain.
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8
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Lin H, Wang C, Zhao H, Chen G, Chen X. A subcellular level study of copper speciation reveals the synergistic mechanism of microbial cells and EPS involved in copper binding in bacterial biofilms. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 263:114485. [PMID: 32298938 DOI: 10.1016/j.envpol.2020.114485] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 03/26/2020] [Accepted: 03/26/2020] [Indexed: 06/11/2023]
Abstract
The synergistic cooperation of microbial cells and their extracellular polymeric substances (EPS) in biofilms is critical for the biofilm's resistance to heavy metals and the migration and transformation of heavy metals. However, the effects of different components of biofilms have not been fully understood. In this study, the spatial distribution and speciation of copper in the colloidal EPS, capsular EPS, cell walls and membranes, and intracellular fraction of unsaturated Pseudomonas putida (P. putida) CZ1 biofilms were fully determined at the subcellular level. It was found that 60-67% of copper was located in the extracellular fraction of biofilms, with 44.7-42.3% in the capsular EPS. In addition, there was 15.5-20.1% and 17.2-21.2% of copper found in the cell walls and membranes or the intracellular fraction, respectively. Moreover, an X-ray absorption fine structure spectra analysis revealed that copper was primarily bound by carboxyl-, phosphate-, and hydrosulfide-like ligands within the extracellular polymeric matrix, cell walls and membranes, and intracellular fraction, respectively. In addition, macromolecule quantification, fourier-transform infrared spectroscopy spectra and sulfur K-edge x-ray absorption near edge structure analysis further showed the carboxyl-rich acidic polysaccharides in EPS, phospholipids in cell walls and cell membranes, and thiol-rich intracellular proteins were involved in binding of copper in the different components of biofilm. The full understanding of the distribution and chemical species of heavy metals in biofilms not only promotes a deep understanding of the interaction mechanisms between biofilms and heavy metals, but also contributes to the development of effective biofilm-based heavy metal pollution remediation technologies.
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Affiliation(s)
- Huirong Lin
- Department of Environmental Science and Engineering, College of Chemical Engineering, Huaqiao University, Xiamen, Fujian, 361021, China
| | - Chengyun Wang
- The First Affiliated Hospital of Xiamen University, Xiamen, 361003, PR China
| | - Hongmei Zhao
- Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, 215123, PR China; Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, PR China
| | - Guancun Chen
- Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, 215123, PR China; Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, PR China.
| | - Xincai Chen
- Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, PR China
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Svenningsen NB, Martínez-García E, Nicolaisen MH, de Lorenzo V, Nybroe O. The biofilm matrix polysaccharides cellulose and alginate both protect Pseudomonas putida mt-2 against reactive oxygen species generated under matric stress and copper exposure. Microbiology (Reading) 2018; 164:883-888. [DOI: 10.1099/mic.0.000667] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Affiliation(s)
- Nanna B. Svenningsen
- Section for Microbial Ecology and Biotechnology, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | | | - Mette H. Nicolaisen
- Section for Microbial Ecology and Biotechnology, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Victor de Lorenzo
- Systems Biology Program, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
| | - Ole Nybroe
- Section for Microbial Ecology and Biotechnology, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark
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Zhang Z, Cai R, Zhang W, Fu Y, Jiao N. A Novel Exopolysaccharide with Metal Adsorption Capacity Produced by a Marine Bacterium Alteromonas sp. JL2810. Mar Drugs 2017; 15:md15060175. [PMID: 28604644 PMCID: PMC5484125 DOI: 10.3390/md15060175] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 06/05/2017] [Accepted: 06/09/2017] [Indexed: 11/16/2022] Open
Abstract
Most marine bacteria can produce exopolysaccharides (EPS). However, very few structures of EPS produced by marine bacteria have been determined. The characterization of EPS structure is important for the elucidation of their biological functions and ecological roles. In this study, the structure of EPS produced by a marine bacterium, Alteromonas sp. JL2810, was characterized, and the biosorption of the EPS for heavy metals Cu2+, Ni2+, and Cr6+ was also investigated. Nuclear magnetic resonance (NMR) analysis indicated that the JL2810 EPS have a novel structure consisting of the repeating unit of [-3)-α-Rhap-(1→3)-α-Manp-(1→4)-α-3OAc-GalAp-(1→]. The biosorption of the EPS for heavy metals was affected by a medium pH; the maximum biosorption capacities for Cu2+ and Ni2+ were 140.8 ± 8.2 mg/g and 226.3 ± 3.3 mg/g at pH 5.0; however, for Cr6+ it was 215.2 ± 5.1 mg/g at pH 5.5. Infrared spectrometry analysis demonstrated that the groups of O-H, C=O, and C-O-C were the main function groups for the adsorption of JL2810 EPS with the heavy metals. The adsorption equilibrium of JL2810 EPS for Ni2+ was further analyzed, and the equilibrium data could be better represented by the Langmuir isotherm model. The novel EPS could be potentially used in industrial applications as a novel bio-resource for the removal of heavy metals.
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Affiliation(s)
- Zilian Zhang
- State Key Laboratory of Marine Environmental Science, Institute of Marine Microbes and Ecospheres, Xiamen University, Xiamen 361102, China.
| | - Ruanhong Cai
- State Key Laboratory of Marine Environmental Science, Institute of Marine Microbes and Ecospheres, Xiamen University, Xiamen 361102, China.
| | - Wenhui Zhang
- State Key Laboratory of Marine Environmental Science, Institute of Marine Microbes and Ecospheres, Xiamen University, Xiamen 361102, China.
| | - Yingnan Fu
- State Key Laboratory of Marine Environmental Science, Institute of Marine Microbes and Ecospheres, Xiamen University, Xiamen 361102, China.
| | - Nianzhi Jiao
- State Key Laboratory of Marine Environmental Science, Institute of Marine Microbes and Ecospheres, Xiamen University, Xiamen 361102, China.
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Henriques I, Tacão M, Leite L, Fidalgo C, Araújo S, Oliveira C, Alves A. Co-selection of antibiotic and metal(loid) resistance in gram-negative epiphytic bacteria from contaminated salt marshes. MARINE POLLUTION BULLETIN 2016; 109:427-434. [PMID: 27210560 DOI: 10.1016/j.marpolbul.2016.05.031] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 05/05/2016] [Accepted: 05/14/2016] [Indexed: 06/05/2023]
Abstract
The goal of this study was to investigate co-selection of antibiotic resistance in gram-negative epiphytic bacteria. Halimione portulacoides samples were collected from metal(loid)-contaminated and non-contaminated salt marshes. Bacterial isolates (n=137) affiliated with Vibrio, Pseudomonas, Shewanella, Comamonas, Aeromonas and with Enterobacteriaceae. Vibrio isolates were more frequent in control site while Pseudomonas was common in contaminated sites. Metal(loid) and antibiotic resistance phenotypes varied significantly according to site contamination, and multiresistance was more frequent in contaminated sites. However, differences among sites were not observed in terms of prevalence or diversity of acquired antibiotic resistance genes, integrons and plasmids. Gene merA, encoding mercury resistance, was only detected in isolates from contaminated sites, most of which were multiresistant to antibiotics. Results indicate that metal(loid) contamination selects for antibiotic resistance in plant surfaces. In salt marshes, antibiotic resistance may be subsequently transferred to other environmental compartments, such as estuarine water or animals, with potential human health risks.
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Affiliation(s)
- Isabel Henriques
- Biology Department, CESAM and iBiMED, University of Aveiro, Aveiro, Portugal.
| | - Marta Tacão
- Biology Department, CESAM and iBiMED, University of Aveiro, Aveiro, Portugal
| | - Laura Leite
- Biology Department, CESAM, University of Aveiro, Aveiro, Portugal
| | - Cátia Fidalgo
- Biology Department, CESAM and iBiMED, University of Aveiro, Aveiro, Portugal
| | - Susana Araújo
- Biology Department, CESAM and iBiMED, University of Aveiro, Aveiro, Portugal
| | - Cláudia Oliveira
- Biology Department, CESAM, University of Aveiro, Aveiro, Portugal
| | - Artur Alves
- Biology Department, CESAM, University of Aveiro, Aveiro, Portugal
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12
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AlgU Controls Expression of Virulence Genes in Pseudomonas syringae pv. tomato DC3000. J Bacteriol 2016; 198:2330-44. [PMID: 27325679 DOI: 10.1128/jb.00276-16] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/14/2016] [Indexed: 01/30/2023] Open
Abstract
UNLABELLED Plant-pathogenic bacteria are able to integrate information about their environment and adjust gene expression to provide adaptive functions. AlgU, an extracytoplasmic function (ECF) sigma factor encoded by Pseudomonas syringae, controls expression of genes for alginate biosynthesis and genes involved with resisting osmotic and oxidative stress. AlgU is active while these bacteria are associated with plants, where its presence supports bacterial growth and disease symptoms. We found that AlgU is an important virulence factor for P. syringae pv. tomato DC3000 but that alginate production is dispensable for disease in host plants. This implies that AlgU regulates additional genes that facilitate bacterial pathogenesis. We used transcriptome sequencing (RNA-seq) to characterize the AlgU regulon and chromatin immunoprecipitation sequencing (ChIP-seq) to identify AlgU-regulated promoters associated with genes directly controlled by this sigma factor. We found that in addition to genes involved with alginate and osmotic and oxidative stress responses, AlgU regulates genes with known virulence functions, including components of the Hrp type III secretion system, virulence effectors, and the hrpL and hrpRS transcription regulators. These data suggest that P. syringae pv. tomato DC3000 has adapted to use signals that activate AlgU to induce expression of important virulence functions that facilitate survival and disease in plants. IMPORTANCE Plant immune systems produce antimicrobial and bacteriostatic conditions in response to bacterial infection. Plant-pathogenic bacteria are adapted to suppress and/or tolerate these conditions; however, the mechanisms controlling these bacterial systems are largely uncharacterized. The work presented here provides a mechanistic explanation for how P. syringae pv. tomato DC3000 coordinates expression of multiple genetic systems, including those dedicated to pathogenicity, in response to environmental conditions. This work demonstrates the scope of AlgU regulation in P. syringae pv. tomato DC3000 and characterizes the promoter sequence regulated by AlgU in these bacteria.
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Park SH, Bao Z, Butcher BG, D'Amico K, Xu Y, Stodghill P, Schneider DJ, Cartinhour S, Filiatrault MJ. Analysis of the small RNA spf in the plant pathogen Pseudomonas syringae pv. tomato strain DC3000. MICROBIOLOGY-SGM 2014; 160:941-953. [PMID: 24600027 DOI: 10.1099/mic.0.076497-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Bacteria contain small non-coding RNAs (ncRNAs) that are typically responsible for altering transcription, translation or mRNA stability. ncRNAs are important because they often regulate virulence factors and susceptibility to various stresses. Here, the regulation of a recently described ncRNA of Pseudomonas syringae DC3000, spot 42 (now referred to as spf), was investigated. A putative RpoE binding site was identified upstream of spf in strain DC3000. RpoE is shown to regulate the expression of spf. Also, deletion of spf results in increased sensitivity to hydrogen peroxide compared with the wild-type strain, suggesting that spf plays a role in susceptibility to oxidative stress. Furthermore, expression of alg8 is shown to be influenced by spf, suggesting that this ncRNA plays a role in alginate biosynthesis. Structural and comparative genomic analyses show this ncRNA is well conserved among the pseudomonads. The findings provide new information on the regulation and role of this ncRNA in P. syringae.
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Affiliation(s)
- So Hae Park
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Zhongmeng Bao
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Bronwyn G Butcher
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Katherine D'Amico
- Plant-Microbe Interactions Research Unit, Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, United States Department of Agriculture, Ithaca, NY 14853, USA.,Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Yun Xu
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Paul Stodghill
- Plant-Microbe Interactions Research Unit, Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, United States Department of Agriculture, Ithaca, NY 14853, USA
| | - David J Schneider
- Plant-Microbe Interactions Research Unit, Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, United States Department of Agriculture, Ithaca, NY 14853, USA.,Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Samuel Cartinhour
- Plant-Microbe Interactions Research Unit, Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, United States Department of Agriculture, Ithaca, NY 14853, USA.,Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - M J Filiatrault
- Plant-Microbe Interactions Research Unit, Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, United States Department of Agriculture, Ithaca, NY 14853, USA.,Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
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Hay ID, Wang Y, Moradali MF, Rehman ZU, Rehm BHA. Genetics and regulation of bacterial alginate production. Environ Microbiol 2014; 16:2997-3011. [DOI: 10.1111/1462-2920.12389] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Revised: 12/18/2013] [Accepted: 12/22/2013] [Indexed: 12/31/2022]
Affiliation(s)
- Iain D. Hay
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Yajie Wang
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Mohammed F. Moradali
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Zahid U. Rehman
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
| | - Bernd H. A. Rehm
- Institute of Fundamental Sciences; Massey University; Palmerston North 4442 New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology; Massey University; Palmerston North 4442 New Zealand
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15
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Copper susceptibility in Acinetobacter junii BB1A is related to the production of extracellular polymeric substances. Antonie van Leeuwenhoek 2013; 104:261-9. [PMID: 23756604 DOI: 10.1007/s10482-013-9946-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 05/30/2013] [Indexed: 10/26/2022]
Abstract
Acinetobacter junii BB1A cells, grown in different media, were differentially inhibited in the presence of the copper. The minimum inhibitory concentration of Cu(2+) was influenced by the nutrient status of the media. The production of extracellular polymeric substances (EPS) was stimulated by the copper present in the growth medium. The nature of the EPS was anionic showing non-Newtonian pseudoplastic behaviour. The thermal behaviour of the EPS was studied by differential scanning calorimetry. The EPS was amorphous in nature with a crystalline index of 0.16. Scanning electron micrographs revealed its porous structure. Cells grown in the presence of quorum sensing inhibitor (QSI: 4-Nitropyridine-N-oxide) did not produce EPS and were found to be more sensitive to Cu(2+) than cells which produced EPS in the absence of QSI. EPS production in different media in the presence and absence of Cu(2+) was determined. The production of EPS was the highest in brain heart Infusion medium and the lowest in AB minimal medium. The sorption of Cu(2+) by EPS extracted from cells grown in non-copper-complexing AB medium was demonstrated by energy dispersive X-ray spectroscopy. A pertinent functional aspect of EPS in providing protection to A. junii in copper stress condition has been revealed.
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16
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Sessitsch A, Kuffner M, Kidd P, Vangronsveld J, Wenzel WW, Fallmann K, Puschenreiter M. The role of plant-associated bacteria in the mobilization and phytoextraction of trace elements in contaminated soils. SOIL BIOLOGY & BIOCHEMISTRY 2013; 60:182-194. [PMID: 23645938 PMCID: PMC3618436 DOI: 10.1016/j.soilbio.2013.01.012] [Citation(s) in RCA: 309] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 01/04/2013] [Accepted: 01/13/2013] [Indexed: 05/04/2023]
Abstract
Phytoextraction makes use of trace element-accumulating plants that concentrate the pollutants in their tissues. Pollutants can be then removed by harvesting plants. The success of phytoextraction depends on trace element availability to the roots and the ability of the plant to intercept, take up, and accumulate trace elements in shoots. Current phytoextraction practises either employ hyperaccumulators or fast-growing high biomass plants; the phytoextraction process may be enhanced by soil amendments that increase trace element availability in the soil. This review will focus on the role of plant-associated bacteria to enhance trace element availability in the rhizosphere. We report on the kind of bacteria typically found in association with trace element - tolerating or - accumulating plants and discuss how they can contribute to improve trace element uptake by plants and thus the efficiency and rate of phytoextraction. This enhanced trace element uptake can be attributed to a microbial modification of the absorptive properties of the roots such as increasing the root length and surface area and numbers of root hairs, or by increasing the plant availability of trace elements in the rhizosphere and the subsequent translocation to shoots via beneficial effects on plant growth, trace element complexation and alleviation of phytotoxicity. An analysis of data from literature shows that effects of bacterial inoculation on phytoextraction efficiency are currently inconsistent. Some key processes in plant-bacteria interactions and colonization by inoculated strains still need to be unravelled more in detail to allow full-scale application of bacteria assisted phytoremediation of trace element contaminated soils.
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Affiliation(s)
- Angela Sessitsch
- AIT Austrian Institute of Technology GmbH, Bioresources Unit, A-3430 Tulln, Austria
| | - Melanie Kuffner
- AIT Austrian Institute of Technology GmbH, Bioresources Unit, A-3430 Tulln, Austria
| | - Petra Kidd
- Instituto de Investigaciones Agrobiológicas de Galicia (IIAG), CSIC, Apdo. 122, 15780 Santiago de Compostela, Spain
| | - Jaco Vangronsveld
- Hasselt University, Centre for Environmental Sciences, B-3590 Diepenbeek, Belgium
| | - Walter W. Wenzel
- University of Natural Resources and Life Sciences Vienna, Department of Forest and Soil Sciences, A-3430 Tulln, Austria
| | - Katharina Fallmann
- AIT Austrian Institute of Technology GmbH, Bioresources Unit, A-3430 Tulln, Austria
- University of Natural Resources and Life Sciences Vienna, Department of Forest and Soil Sciences, A-3430 Tulln, Austria
| | - Markus Puschenreiter
- University of Natural Resources and Life Sciences Vienna, Department of Forest and Soil Sciences, A-3430 Tulln, Austria
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17
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Thakur PB, Vaughn-Diaz VL, Greenwald JW, Gross DC. Characterization of five ECF sigma factors in the genome of Pseudomonas syringae pv. syringae B728a. PLoS One 2013; 8:e58846. [PMID: 23516563 PMCID: PMC3597554 DOI: 10.1371/journal.pone.0058846] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 02/07/2013] [Indexed: 11/18/2022] Open
Abstract
Pseudomonas syringae pv. syringae B728a, a bacterial pathogen of bean, utilizes large surface populations and extracellular signaling to initiate a fundamental change from an epiphytic to a pathogenic lifestyle. Extracytoplasmic function (ECF) sigma (σ) factors serve as important regulatory factors in responding to various environmental signals. Bioinformatic analysis of the B728a genome revealed 10 ECF sigma factors. This study analyzed deletion mutants of five previously uncharacterized ECF sigma factor genes in B728a, including three FecI-type ECF sigma factors (ECF5, ECF6, and ECF7) and two ECF sigma factors placed in groups ECF11 and ECF18. Transcriptional profiling by qRT-PCR analysis of ECF sigma factor mutants was used to measure expression of their associated anti-sigma and outer membrane receptor proteins, and expression of genes associated with production of extracellular polysaccharides, fimbriae, glycine betaine and syringomycin. Notably, the B728aΔecf7 mutant displayed reduced swarming and had decreased expression of CupC fimbrial genes. Growth and pathogenicity assays, using a susceptible bean host, revealed that none of the tested sigma factor genes are required for in planta growth and lesion formation.
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Affiliation(s)
- Poulami Basu Thakur
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
| | - Vanessa L. Vaughn-Diaz
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
| | - Jessica W. Greenwald
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
| | - Dennis C. Gross
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
- * E-mail: .
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18
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Besaury L, Marty F, Buquet S, Mesnage V, Muyzer G, Quillet L. Culture-dependent and independent studies of microbial diversity in highly copper-contaminated Chilean marine sediments. MICROBIAL ECOLOGY 2013; 65:311-324. [PMID: 22976340 DOI: 10.1007/s00248-012-0120-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 08/29/2012] [Indexed: 06/01/2023]
Abstract
Cultivation and molecular-based approaches were used to study microbial diversity in two Chilean marine sediments contaminated with high (835 ppm) and very high concentrations of copper (1,533 ppm). The diversity of cultivable bacteria resistant to copper was studied at oxic and anoxic conditions, focusing on sulfate-, thiosulfate-, and iron-reducing bacteria. For both sediments, the cultivable bacteria isolated at oxic conditions were mostly affiliated to the genus Bacillus, while at anoxic conditions the majority of the cultivable bacteria found were closely related to members of the genera Desulfovibrio, Sphingomonas, and Virgibacillus. Copper resistance was between 100 and 400 ppm, with the exception of a strain affiliated to members of the genus Desulfuromonas, which was resistant up to 1,000 ppm of copper. In parallel, cloning and sequencing of 16S rRNA was performed to study the total bacterial diversity in the sediments. A weak correlation was observed between the isolated strains and the 16S rRNA operational taxonomic units detected. The presence of copper resistance genes (copA, cusA, and pcoA) was tested for all the strains isolated; only copA was detected in a few isolates, suggesting that other copper resistance mechanisms could be used by the bacteria in those highly copper-contaminated sediments.
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Affiliation(s)
- Ludovic Besaury
- UMR CNRS 6143 M2C-groupe Microbiologie, Université de Rouen, Mont Saint Aignan, Rouen, France.
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Park SH, Butcher BG, Anderson Z, Pellegrini N, Bao Z, D’Amico K, Filiatrault MJ. Analysis of the small RNA P16/RgsA in the plant pathogen Pseudomonas syringae pv. tomato strain DC3000. MICROBIOLOGY-SGM 2012; 159:296-306. [PMID: 23258266 PMCID: PMC3709562 DOI: 10.1099/mic.0.063826-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Bacteria contain small non-coding RNAs (ncRNAs) that are responsible for altering transcription, translation or mRNA stability. ncRNAs are important because they regulate virulence factors and susceptibility to various stresses. Here, the regulation of a recently described ncRNA of Pseudomonas syringae pv. tomato DC3000, P16, was investigated. We determined that RpoS regulates the expression of P16. We found that deletion of P16 results in increased sensitivity to hydrogen peroxide compared to the wild-type strain, suggesting that P16 plays a role in the bacteria’s susceptibility to oxidative stress. Additionally the P16 mutant displayed enhanced resistance to heat stress. Our findings provide new information on the regulation and role of this ncRNA in P. syringae.
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Affiliation(s)
- So Hae Park
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Bronwyn G. Butcher
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Zoe Anderson
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Nola Pellegrini
- Plant–Microbe Interactions Research Unit, Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, United States Department of Agriculture, Ithaca, NY 14853, USA
| | - Zhongmeng Bao
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
| | - Katherine D’Amico
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
- Plant–Microbe Interactions Research Unit, Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, United States Department of Agriculture, Ithaca, NY 14853, USA
| | - Melanie J. Filiatrault
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
- Plant–Microbe Interactions Research Unit, Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, United States Department of Agriculture, Ithaca, NY 14853, USA
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20
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Raza W, Yang W, Jun Y, Shakoor F, Huang Q, Shen Q. Optimization and characterization of a polysaccharide produced by Pseudomonas fluorescens WR-1 and its antioxidant activity. Carbohydr Polym 2012; 90:921-9. [DOI: 10.1016/j.carbpol.2012.06.021] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 05/17/2012] [Accepted: 06/10/2012] [Indexed: 11/16/2022]
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21
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Kong HS, Roberts DP, Patterson CD, Kuehne SA, Heeb S, Lakshman DK, Lydon J. Effect of overexpressing rsmA from Pseudomonas aeruginosa on virulence of select phytotoxin-producing strains of P. syringae. PHYTOPATHOLOGY 2012; 102:575-587. [PMID: 22568815 DOI: 10.1094/phyto-09-11-0267] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The GacS/GacA two-component system functions mechanistically in conjunction with global post-transcriptional regulators of the RsmA family to allow pseudomonads and other bacteria to adapt to changing environmental stimuli. Analysis of this Gac/Rsm signal transduction pathway in phytotoxin-producing pathovars of Pseudmonas syringae is incomplete, particularly with regard to rsmA. Our approach in studying it was to overexpress rsmA in P. syringae strains through introduction of pSK61, a plasmid constitutively expressing this gene. Disease and colonization of plant leaf tissue were consistently diminished in all P. syringae strains tested (pv. phaseolicola NPS3121, pv. syringae B728a, and BR2R) when harboring pSK61 relative to these isolates harboring the empty vector pME6031. Phaseolotoxin, syringomycin, and tabtoxin were not produced in any of these strains when transformed with pSK61. Production of protease and pyoverdin as well as swarming were also diminished in all of these strains when harboring pSK61. In contrast, alginate production, biofilm formation, and the hypersensitive response were diminished in some but not all of these isolates under the same growth conditions. These results indicate that rsmA is consistently important in the overarching phenotypes disease and endophtyic colonization but that its role varies with pathovar in certain underpinning phenotypes in the phytotoxin-producing strains of P. syringae.
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Affiliation(s)
- Hye Suk Kong
- Center for Biologics Evaluation and Research, Food and Drug Administration, Rockville, MD 20852, USA
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22
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Mann EE, Wozniak DJ. Pseudomonas biofilm matrix composition and niche biology. FEMS Microbiol Rev 2012; 36:893-916. [PMID: 22212072 DOI: 10.1111/j.1574-6976.2011.00322.x] [Citation(s) in RCA: 376] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 12/18/2011] [Accepted: 12/19/2011] [Indexed: 11/27/2022] Open
Abstract
Biofilms are a predominant form of growth for bacteria in the environment and in the clinic. Critical for biofilm development are adherence, proliferation, and dispersion phases. Each of these stages includes reinforcement by, or modulation of, the extracellular matrix. Pseudomonas aeruginosa has been a model organism for the study of biofilm formation. Additionally, other Pseudomonas species utilize biofilm formation during plant colonization and environmental persistence. Pseudomonads produce several biofilm matrix molecules, including polysaccharides, nucleic acids, and proteins. Accessory matrix components shown to aid biofilm formation and adaptability under varying conditions are also produced by pseudomonads. Adaptation facilitated by biofilm formation allows for selection of genetic variants with unique and distinguishable colony morphology. Examples include rugose small-colony variants and wrinkly spreaders (WS), which over produce Psl/Pel or cellulose, respectively, and mucoid bacteria that over produce alginate. The well-documented emergence of these variants suggests that pseudomonads take advantage of matrix-building subpopulations conferring specific benefits for the entire population. This review will focus on various polysaccharides as well as additional Pseudomonas biofilm matrix components. Discussions will center on structure-function relationships, regulation, and the role of individual matrix molecules in niche biology.
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Affiliation(s)
- Ethan E Mann
- Department of Microbial Infection and Immunity, Department of Microbiology, Center for Microbial Interface Biology, The Ohio State University Medical Center, Columbus, OH 43210, USA
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Llop P, Barbé S, López MM. Functions and origin of plasmids in Erwinia species that are pathogenic to or epiphytically associated with pome fruit trees. TREES (BERLIN, GERMANY : WEST) 2011; 26:31-46. [PMID: 25983394 PMCID: PMC4425259 DOI: 10.1007/s00468-011-0630-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 09/17/2011] [Accepted: 09/21/2011] [Indexed: 05/29/2023]
Abstract
The genus Erwinia includes plant-associated pathogenic and non-pathogenic species. Among them, all species pathogenic to pome fruit trees (E. amylovora, E. pyrifoliae, E. piriflorinigrans, Erwinia sp. from Japan) cause similar symptoms, but differ in their degrees of aggressiveness, i.e. in symptoms, host range or both. The presence of plasmids of similar size, in the range of 30 kb, is a common characteristic that they possess. Besides, they share some genetic content with high homology in several genes associated with exopolysaccharide production and hence, with virulence, as well as in some other genes. Knowledge of the content of these plasmids and comparative genetic analyses may provide interesting new clues to understanding the origin and evolution of these pathogens and the level of symptoms they produce. Furthermore, genetic similarities observed among some of the plasmids (and genomes) from the above indicated pathogenic species and E. tasmaniensis or E. billingiae, which are epiphytic on the same hosts, may reveal associations that could expose the mechanisms of origin of pathogens. A summary of the current information on their plasmids and the relationships among them is presented here.
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Affiliation(s)
- Pablo Llop
- Instituto Valenciano de Investigaciones Agrarias (IVIA), Ctra. Moncada-Náquera Km 4.5, 46113 Moncada, Valencia Spain
| | - Silvia Barbé
- Instituto Valenciano de Investigaciones Agrarias (IVIA), Ctra. Moncada-Náquera Km 4.5, 46113 Moncada, Valencia Spain
| | - María M. López
- Instituto Valenciano de Investigaciones Agrarias (IVIA), Ctra. Moncada-Náquera Km 4.5, 46113 Moncada, Valencia Spain
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Ramakrishnan B, Megharaj M, Venkateswarlu K, Sethunathan N, Naidu R. Mixtures of environmental pollutants: effects on microorganisms and their activities in soils. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2011; 211:63-120. [PMID: 21287391 DOI: 10.1007/978-1-4419-8011-3_3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Soil is the ultimate sink for most contaminants and rarely has only a single contaminant. More than is generally acknowledge, environmental pollutants exist as mixtures (organic-organic, inorganic-inorganic, and organic-inorganic). It is much more difficult to study chemical mixtures than individual chemicals, especially in the complex soil environment. Similarly, understanding the toxicity of a chemical mixture on different microbial species is much more complex, time consuming and expensive, because multiple testing designs are needed for an increased array of variables. Therefore, until now, scientific enquiries worldwide have extensively addressed the effects of only individual pollutants toward nontarget microorganisms. In this review, we emphasize the present status of research on (i) the environmental occurrence of pollutant mixtures; (ii) the interactions between pollutant mixtures and ecologically beneficial microorganisms; and (iii) the impact of such interactions on environmental quality. We also address the limitations of traditional cultivation based methods for monitoring the effects of pollutant mixtures on microorganisms. Long-term monitoring of the effects of pollutant mixtures on microorganisms, particularly in soil and aquatic ecosystems, has received little attention. Microbial communities that can degrade or can degrade or can develop tolerance to, or are inhibited by chemical mixtures greatly contribute to resilience and resistance in soil environments. We also stress in this review the important emerging trend associated with the employment of molecular methods for establishing the effects of pollutant mixtures on microbial communities. There is currently a lack of sufficient cogent toxicological data on chemical mixtures for making informed decision making in risk assessment by regulators. Therefore, not only more toxicology information on mixtures is needed but also there is an urgent need to generate sufficient, suitable, and long-term modeling data that have higher predictability when assessing pollutant mixture effects on microorganisms. Such data would improve risk assessment at contaminated sites and would help devise more effective bioremediation strategies.
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25
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Ordax M, Marco-Noales E, López MM, Biosca EG. Exopolysaccharides favor the survival of Erwinia amylovora under copper stress through different strategies. Res Microbiol 2010; 161:549-55. [DOI: 10.1016/j.resmic.2010.05.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Revised: 04/30/2010] [Accepted: 05/04/2010] [Indexed: 10/19/2022]
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26
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Penaloza-Vazquez A, Sreedharan A, Bender CL. Transcriptional studies of the hrpM/opgH gene in Pseudomonas syringae during biofilm formation and in response to different environmental challenges. Environ Microbiol 2010; 12:1452-67. [PMID: 20132277 DOI: 10.1111/j.1462-2920.2010.02160.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Pseudomonas syringae pv. syringae strain FF5 is a phytopathogen that causes a rapid dieback on ornamental pear trees. In the present study, the transcriptional expression of hrpM/opgH, algD, hrpR and rpoD was evaluated in P. syringae FF5 and FF5.M2 (hrpM/opgH mutant). The temporal expression of these genes was evaluated during biofilm formation, the hypersensitive reaction (HR) on tobacco plants, and when the bacteria were subjected to different environmental stresses. The results indicate that mutations in hrpM negatively impair several traits including biofilm formation, the ability to cause disease in host plants and the HR in non-host plants, and the expression of hrpR, a regulatory gene modulating the latter two traits. Furthermore, FF5.M2 was decreased in swarming motility and unable to respond to different environmental challenges. Interestingly, FF5.M2 showed an exponential increase in the expression of algD, which is the first gene to be transcribed during the biosynthesis of the alginate, a virulence factor in P. syringae. The expression of both hrpM and algD were required for biofilm formation, and hrpM was expressed earlier than algD during biofilm development. These findings indicate that hrpM expression is required for several traits in P. syringae and plays an important role in how this bacterium responds to environmental challenges.
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Affiliation(s)
- Alejandro Penaloza-Vazquez
- 127 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
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28
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Schenk A, Weingart H, Ullrich MS. The alternative sigma factor AlgT, but not alginate synthesis, promotes in planta multiplication of Pseudomonas syringae pv. glycinea. MICROBIOLOGY (READING, ENGLAND) 2008; 154:413-421. [PMID: 18227245 DOI: 10.1099/mic.0.2007/012864-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
The phytopathogen Pseudomonas syringae pv. glycinea produces the exopolysaccharide (EPS) alginate, which is thought to function in epiphytic fitness and virulence. A key regulator for alginate biosynthesis in Pseudomonas aeruginosa and P. syringae is the alternative sigma factor AlgT (sigma(22)). In this study, the contribution of alginate synthesis and AlgT to in planta epiphytic fitness and virulence of P. syringae was examined. Alginate biosynthesis mutants were generated for the P. syringae pv. glycinea strains PG4180 and PG4180.muc, representing a comprehensive set of alginate- and AlgT-positive or -negative derivatives. Analysis of in vitro and in planta phenotypes revealed that AlgT strongly promoted in planta growth, survival and symptom development, but decreased the ability to grow in vitro. In contrast, alginate biosynthesis had only marginal impact. Quantitative in vitro and in planta gene expression analyses for alginate biosynthesis and algT were carried out at two temperatures in AlgT-negative and -positive backgrounds. algT as well as algD gene expression was AlgT-dependent, plant-inducible and temperature-dependent, with higher expression at 18 compared to 28 degrees C; however, no temperature dependence was observed in vitro. Our data suggest that AlgT may act as a global regulator for virulence and in planta fitness traits of P. syringae independent of its role in EPS biosynthesis.
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Affiliation(s)
- Alexander Schenk
- Jacobs University Bremen, School of Engineering and Sciences, Campus Ring 1, 28759 Bremen, Germany
| | - Helge Weingart
- Jacobs University Bremen, School of Engineering and Sciences, Campus Ring 1, 28759 Bremen, Germany
| | - Matthias S Ullrich
- Jacobs University Bremen, School of Engineering and Sciences, Campus Ring 1, 28759 Bremen, Germany
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29
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Endophytes and Rhizosphere Bacteria of Plants Growing in Heavy Metal-Containing Soils. SOIL BIOLOGY 2008. [DOI: 10.1007/978-3-540-74231-9_15] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Chang WS, van de Mortel M, Nielsen L, Nino de Guzman G, Li X, Halverson LJ. Alginate production by Pseudomonas putida creates a hydrated microenvironment and contributes to biofilm architecture and stress tolerance under water-limiting conditions. J Bacteriol 2007; 189:8290-9. [PMID: 17601783 PMCID: PMC2168710 DOI: 10.1128/jb.00727-07] [Citation(s) in RCA: 207] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Biofilms exist in a variety of habitats that are routinely or periodically not saturated with water, and residents must integrate cues on water abundance (matric stress) or osmolarity (solute stress) into lifestyle strategies. Here we examine this hypothesis by assessing the extent to which alginate production by Pseudomonas putida strain mt-2 and by other fluorescent pseudomonads occurs in response to water limitations and how the presence of alginate in turn influences biofilm development and stress tolerance. Total exopolysaccharide (EPS) and alginate production increased with increasing matric, but not solute, stress severity, and alginate was a significant component, but not the major component, of EPS. Alginate influenced biofilm architecture, resulting in biofilms that were taller, covered less surface area, and had a thicker EPS layer at the air interface than those formed by an mt-2 algD mutant under water-limiting conditions, properties that could contribute to less evaporative water loss. We examined this possibility and show that alginate reduces the extent of water loss from biofilm residents by using a biosensor to quantify the water potential of individual cells and by measuring the extent of dehydration-mediated changes in fatty acid composition following a matric or solute stress shock. Alginate deficiency decreased survival of desiccation not only by P. putida but also by Pseudomonas aeruginosa PAO1 and Pseudomonas syringae pv. syringae B728a. Our findings suggest that in response to water-limiting conditions, pseudomonads produce alginate, which influences biofilm development and EPS physiochemical properties. Collectively these responses may facilitate the maintenance of a hydrated microenvironment, protecting residents from desiccation stress and increasing survival.
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Affiliation(s)
- Woo-Suk Chang
- Graduate Program in Microbiology, Iowa State University, Ames, Iowa 50011, USA
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Quaranta D, McCarty R, Bandarian V, Rensing C. The copper-inducible cin operon encodes an unusual methionine-rich azurin-like protein and a pre-Q0 reductase in Pseudomonas putida KT2440. J Bacteriol 2007; 189:5361-71. [PMID: 17483220 PMCID: PMC1951875 DOI: 10.1128/jb.00377-07] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genome sequences of several pseudomonads have revealed a gene cluster containing genes for a two-component heavy metal histidine sensor kinase and response regulator upstream of cinA and cinQ, which we show herein to encode a copper-containing azurin-like protein and a pre-Q(0) reductase, respectively. In the presence of copper, Pseudomonas putida KT2440 produces the CinA and CinQ proteins from a bicistronic mRNA. UV-visible spectra of CinA show features at 439, 581, and 719 nm, which is typical of the plastocyanin family of proteins. The redox potential of the protein was shown to be 456 +/- 4 mV by voltametric titrations. Surprisingly, CinQ is a pyridine nucleotide-dependent nitrile oxidoreductase that catalyzes the conversion of pre-Q(0) to pre-Q(1) in the nucleoside queuosine biosynthetic pathway. Gene disruptions of cinA and cinQ did not lead to a significant increase in the copper sensitivity of P. putida KT2440 under the conditions tested. Possible roles of CinA and CinQ to help pseudomonads adapt and survive under prolonged copper stress are discussed.
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Affiliation(s)
- Davide Quaranta
- Department of Soil, Water, and Environmental Science, University of Arizona, Shantz Blvd. #38, Rm. 429, Tucson, AZ 85721, USA
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Schenk A, Berger M, Keith LM, Bender CL, Muskhelishvili G, Ullrich MS. The algT gene of Pseudomonas syringae pv. glycinea and new insights into the transcriptional organization of the algT-muc gene cluster. J Bacteriol 2006; 188:8013-21. [PMID: 17012388 PMCID: PMC1698189 DOI: 10.1128/jb.01160-06] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2006] [Accepted: 08/31/2006] [Indexed: 01/22/2023] Open
Abstract
The phytopathogenic bacterium Pseudomonas syringae pv. glycinea infects soybean plants and causes bacterial blight. In addition to P. syringae, the human pathogen Pseudomonas aeruginosa and the soil bacterium Azotobacter vinelandii produce the exopolysaccharide alginate, a copolymer of d-mannuronic and l-guluronic acids. Alginate production in P. syringae has been associated with increased fitness and virulence in planta. Alginate biosynthesis is tightly controlled by proteins encoded by the algT-muc regulatory gene cluster in P. aeruginosa and A. vinelandii. These genes encode the alternative sigma factor AlgT (sigma(22)), its anti-sigma factors MucA and MucB, MucC, a protein with a controversial function that is absent in P. syringae, and MucD, a periplasmic serine protease and homolog of HtrA in Escherichia coli. We compared an alginate-deficient algT mutant of P. syringae pv. glycinea with an alginate-producing derivative in which algT is intact. The alginate-producing derivative grew significantly slower in vitro growth but showed increased epiphytic fitness and better symptom development in planta. Evaluation of expression levels for algT, mucA, mucB, mucD, and algD, which encodes an alginate biosynthesis gene, showed that mucD transcription is not dependent on AlgT in P. syringae in vitro. Promoter mapping using primer extension experiments confirmed this finding. Results of reverse transcription-PCR demonstrated that algT, mucA, and mucB are cotranscribed as an operon in P. syringae. Northern blot analysis revealed that mucD was expressed as a 1.75-kb monocistronic mRNA in P. syringae.
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Affiliation(s)
- Alexander Schenk
- School of Engineering and Sciences, Campus Ring 1, International University Bremen, D-28759 Bremen, Germany
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Baker-Austin C, Wright MS, Stepanauskas R, McArthur JV. Co-selection of antibiotic and metal resistance. Trends Microbiol 2006; 14:176-82. [PMID: 16537105 DOI: 10.1016/j.tim.2006.02.006] [Citation(s) in RCA: 1064] [Impact Index Per Article: 59.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2005] [Revised: 02/02/2006] [Accepted: 02/23/2006] [Indexed: 11/25/2022]
Abstract
There is growing concern that metal contamination functions as a selective agent in the proliferation of antibiotic resistance. Documented associations between the types and levels of metal contamination and specific patterns of antibiotic resistance suggest that several mechanisms underlie this co-selection process. These co-selection mechanisms include co-resistance (different resistance determinants present on the same genetic element) and cross-resistance (the same genetic determinant responsible for resistance to antibiotics and metals). Indirect but shared regulatory responses to metal and antibiotic exposure such as biofilm induction also represent potential co-selection mechanisms used by prokaryotes. Metal contamination, therefore, represents a long-standing, widespread and recalcitrant selection pressure with both environmental and clinical importance that potentially contributes to the maintenance and spread of antibiotic resistance factors.
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Moreno-Garrido I, Campana O, Lubián LM, Blasco J. Calcium alginate immobilized marine microalgae: experiments on growth and short-term heavy metal accumulation. MARINE POLLUTION BULLETIN 2005; 51:823-9. [PMID: 16026804 DOI: 10.1016/j.marpolbul.2005.06.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Growth of 11 calcium alginate immobilized marine microalgal species belonging to eight taxonomical groups has been checked in the present work. Cellular densities inside the calcium alginate beads were monitored during 17 days. Good growth and maintenance of the structure of the beads were both found for some of the assayed species. One of those species (Tetraselmis chui, Prasinophyceae) was selected in order to perform a short term (up to 24 h) heavy metal accumulation experiment. Beads of calcium alginate containing (or not) cells of T. chui were exposed to 820 microg L(-1) Cu and 870 microg L(-1) Cd separately during a 24 h period, and accumulation of heavy metals in the beads was measured after this time and compared. Concentration of each metal in the supernatants was monitored at 5, 10, 60 min and 24 h from the beginning of the experiment. After 24 h, practically all Cu was removed by the beads. Beads with immobilized algae removed around 20% of total Cd, while beads without algae removed half of that percentage.
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Affiliation(s)
- I Moreno-Garrido
- Institute of Marine Sciences of Andalucia (CSIC), Campus Río San Pedro, 11510 Puerto Real, Cádiz (España), Spain.
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Peñaloza-Vázquez A, Fakhr MK, Bailey AM, Bender CL. AlgR functions in algC expression and virulence in Pseudomonas syringae pv. syringae. MICROBIOLOGY-SGM 2004; 150:2727-2737. [PMID: 15289569 DOI: 10.1099/mic.0.27199-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Pseudomonas syringae pv. syringae strain FF5 is a phytopathogen associated with a rapid dieback on ornamental pear trees. P. syringae and the human pathogen Pseudomonas aeruginosa produce the exopolysaccharide alginate, a copolymer of mannuronic and guluronic acid. In P. aeruginosa, the response regulator AlgR (AlgR1) is required for transcription of algC and algD, which encode key enzymes in the alginate biosynthetic pathway. In P. syringae FF5, however, algR is not required for the activation of algD. Interestingly, algR mutants of P. syringae remain nonmucoid, indicating an undefined role for this response regulator in alginate biosynthesis. In the current study, the algC promoter region was cloned from P. syringae pv. syringae strain FF5, and sequence analysis of the algC promoter indicated the presence of potential binding sites for AlgR and sigma(54), the alternative sigma factor encoded by rpoN. The algC promoter from P. syringae FF5 (PsalgC) was cloned upstream of a promoterless glucuronidase gene (uidA), and the PsalgC-uidA transcriptional fusion was used to monitor algC expression in strains FF5.32 (algR mutant of P. syringae FF5) and PG4180.K2 (rpoN mutant of P. syringae pv. glycinea PG4180). Expression of the PsalgC-uidA fusion was fourfold lower in both the algR and rpoN mutants as compared to respective wild-type strains, indicating that both AlgR and sigma(54) are required for full activation of algC transcription in P. syringae pv. syringae. AlgR from P. syringae was successfully overproduced in Escherichia coli as a C-terminal translational fusion to the maltose-binding protein (MBP). Gel shift experiments indicated that MBP-AlgR binds strongly to the algC promoter region. Biological assays demonstrated that the algR mutant was significantly impaired in both pathogenicity and epiphytic fitness as compared to the wild-type strain. These results, along with the gene expression studies, indicate that AlgR has a positive role in the activation of algC in P. syringae and contributes to both virulence and epiphytic fitness. Furthermore, the symptoms observed with wild-type P. syringae FF5 suggest that this strain can move systemically in leaf tissue, and that a functional copy of algR is required for systemic movement.
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Affiliation(s)
| | - Mohamed K Fakhr
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
| | - Ana M Bailey
- Departamento de Ingeniería Genética de Plantas CINVESTAV-IPN Unidad Irapuato, Irapuato, Guanajuato, 36500 Mexico
| | - Carol L Bender
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
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Keith RC, Keith LMW, Hernández-Guzmán G, Uppalapati SR, Bender CL. Alginate gene expression by Pseudomonas syringae pv. tomato DC3000 in host and non-host plants. MICROBIOLOGY (READING, ENGLAND) 2003; 149:1127-1138. [PMID: 12724374 DOI: 10.1099/mic.0.26109-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Pseudomonas syringae produces the exopolysaccharide alginate, a copolymer of mannuronic and guluronic acid. Although alginate has been isolated from plants infected by P. syringae, the signals and timing of alginate gene expression in planta have not been described. In this study, an algD : : uidA transcriptional fusion, designated pDCalgDP, was constructed and used to monitor alginate gene expression in host and non-host plants inoculated with P. syringae pv. tomato DC3000. When leaves of susceptible collard plants were spray-inoculated with DC3000(pDCalgDP), algD was activated within 72 h post-inoculation (p.i.) and was associated with the development of water-soaked lesions. In leaves of the susceptible tomato cv. Rio Grande-PtoS, algD activity was lower than in collard and was not associated with water-soaking. The expression of algD was also monitored in leaves of tomato cv. Rio Grande-PtoR, which is resistant to P. syringae pv. tomato DC3000. Within 12 h p.i., a microscopic hypersensitive response (micro-HR) was observed in Rio Grande-PtoR leaves spray-inoculated with P. syringae pv. tomato DC3000(pDCalgDP). As the HR progressed, histochemical staining indicated that individual bacterial cells on the surface of resistant tomato leaves were expressing algD. These results indicate that algD is expressed in both susceptible (e.g. collard, tomato) and resistant (Rio Grande-PtoR) host plants. The expression of algD in an incompatible host-pathogen interaction was further explored by monitoring transcriptional activity in leaves of tobacco, which is not a host for P. syringae pv. tomato. In tobacco inoculated with DC3000(pDCalgDP), an HR was evident within 12 h p.i., and algD expression was evident within 8-12 h p.i. However, when tobacco was inoculated with an hrcC mutant of DC3000, the HR did not occur and algD expression was substantially lower. These results suggest that signals that precede the HR may stimulate alginate gene expression in P. syringae. Histochemical staining with nitro blue tetrazolium indicated that the superoxide anion () is a signal for algD activation in planta. This study indicates that algD is expressed when P. syringae attempts to colonize both susceptible and resistant plant hosts.
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Affiliation(s)
- Ronald C Keith
- 127 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Lisa M W Keith
- 127 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Gustavo Hernández-Guzmán
- 127 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Srinivasa R Uppalapati
- 127 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Carol L Bender
- 127 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
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Vivian A, Murillo J, Jackson RW. The roles of plasmids in phytopathogenic bacteria: mobile arsenals? MICROBIOLOGY (READING, ENGLAND) 2001; 147:763-780. [PMID: 11283273 DOI: 10.1099/00221287-147-4-763] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Alan Vivian
- Centre for Research in Plant Science, Faculty of Applied Sciences, UWE-Bristol, Coldharbour Lane, Bristol BS16 1QY, UK1
| | - Jesús Murillo
- Centre for Research in Plant Science, Faculty of Applied Sciences, UWE-Bristol, Coldharbour Lane, Bristol BS16 1QY, UK1
| | - Robert W Jackson
- Centre for Research in Plant Science, Faculty of Applied Sciences, UWE-Bristol, Coldharbour Lane, Bristol BS16 1QY, UK1
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Preston LA, Wong TY, Bender CL, Schiller NL. Characterization of alginate lyase from Pseudomonas syringae pv. syringae. J Bacteriol 2000; 182:6268-71. [PMID: 11029455 PMCID: PMC94769 DOI: 10.1128/jb.182.21.6268-6271.2000] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The gene encoding alginate lyase (algL) in Pseudomonas syringae pv. syringae was cloned, sequenced, and overexpressed in Escherichia coli. Alginate lyase activity was optimal when the pH was 7.0 and when assays were conducted at 42 degrees C in the presence of 0.2 M NaCl. In substrate specificity studies, AlgL from P. syringae showed a preference for deacetylated polymannuronic acid. Sequence alignment with other alginate lyases revealed conserved regions within AlgL likely to be important for the structure and/or function of the enzyme. Site-directed mutagenesis of histidine and tryptophan residues at positions 204 and 207, respectively, indicated that these amino acids are critical for lyase activity.
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Affiliation(s)
- L A Preston
- Division of Biomedical Sciences, University of California, Riverside, California 92521, USA
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Ullrich MS, Schergaut M, Boch J, Ullrich B. Temperature-responsive genetic loci in the plant pathogen Pseudomonas syringae pv. glycinea. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 10):2457-2468. [PMID: 11021922 DOI: 10.1099/00221287-146-10-2457] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Plant-pathogenic bacteria may sense variations in environmental factors, such as temperature, to adapt to plant-associated habitats during pathogenesis or epiphytic growth. The bacterial blight pathogen of soybean, Pseudomonas syringae pv. glycinea PG4180, preferentially produces the phytotoxin coronatine at 18 degrees C and infects the host plant under conditions of low temperature and high humidity. A miniTn5-based promoterless glucuronidase (uidA) reporter gene was used to identify genetic loci of PG4180 preferentially expressed at 18 or 28 degrees C. Out of 7500 transposon mutants, 61 showed thermoregulated uidA expression as determined by a three-step screening procedure. Two-thirds of these mutants showed an increased reporter gene expression at 18 degrees C whilst the remainder exhibited higher uidA expression at 28 degrees C. MiniTn5-uidA insertion loci from these mutants were subcloned and their nucleotide sequences were determined. Several of the mutants induced at 18 degrees C contained the miniTn5-uidA insertion within the 32.8 kb coronatine biosynthetic gene cluster. Among the other mutants with increased uidA expression at 18 degrees C, insertions were found in genes encoding formaldehyde dehydrogenase, short-chain dehydrogenase and mannuronan C-5-epimerase, in a plasmid-borne replication protein, and in the hrpT locus, involved in pathogenicity of P. syringae. Among the mutants induced at 28 degrees C, insertions disrupted loci with similarities to a repressor of conjugal plasmid transfer, UV resistance determinants, an isoflavanoid-degrading enzyme, a HU-like DNA-binding protein, two additional regulatory proteins, a homologue of bacterial adhesins, transport proteins, LPS synthesis enzymes and two proteases. Genetic loci from 13 mutants did not show significant similarities to any database entries. Results of plant inoculations showed that three of the mutants tested were inhibited in symptom development and in planta multiplication rates. Temperature-shift experiments suggested that all of the identified loci showed a rather slow induction of expression upon change of temperature.
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Affiliation(s)
- Matthias S Ullrich
- Max-Planck-Institut für terrestrische Mikrobiologie, Karl-von-Frisch-Strasse, 35043 Marburg, Germany1
| | - Marion Schergaut
- Max-Planck-Institut für terrestrische Mikrobiologie, Karl-von-Frisch-Strasse, 35043 Marburg, Germany1
| | - Jens Boch
- Max-Planck-Institut für terrestrische Mikrobiologie, Karl-von-Frisch-Strasse, 35043 Marburg, Germany1
| | - Beate Ullrich
- Max-Planck-Institut für terrestrische Mikrobiologie, Karl-von-Frisch-Strasse, 35043 Marburg, Germany1
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Keith LM, Bender CL. AlgT (sigma22) controls alginate production and tolerance to environmental stress in Pseudomonas syringae. J Bacteriol 1999; 181:7176-84. [PMID: 10572118 PMCID: PMC103677 DOI: 10.1128/jb.181.23.7176-7184.1999] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa and the phytopathogen P. syringae produce the exopolysaccharide alginate, which is a copolymer of D-mannuronic and L-guluronic acids. One of the key regulatory genes controlling alginate biosynthesis in P. aeruginosa is algT, which encodes the alternate sigma factor, sigma(22). In the present study, the algT gene product from P. syringae pv. syringae showed 90% amino acid identity with its P. aeruginosa counterpart, and sequence analysis of the region flanking algT in P. syringae revealed the presence of nadB, mucA, and mucB in an arrangement virtually identical to that of P. aeruginosa. An algT mutant of P. syringae was defective in alginate production but could be complemented with wild-type algT from P. syringae or P. aeruginosa when expressed in trans. The algT mutant also displayed increased sensitivity to heat, paraquat, and hydrogen peroxide (H(2)O(2)); the latter two compounds are known to generate reactive oxygen intermediates. Signals for activation of algT gene expression in P. syringae were investigated with an algT::uidA transcriptional fusion. Like that in P. aeruginosa, algT transcription in P. syringae was activated by heat shock. However, algT expression in P. syringae was also stimulated by osmotic stress and by exposure to paraquat, H(2)O(2), and copper sulfate. The latter two compounds are frequently encountered during colonization of plant tissue and may be unique signals for algT activation in P. syringae.
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Affiliation(s)
- L M Keith
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma 74078, USA
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Singh N, Asthana R, Kayastha A, Pandey S, Chaudhary A, Singh S. Thiol and exopolysaccharide production in a cyanobacterium under heavy metal stress. Process Biochem 1999. [DOI: 10.1016/s0032-9592(99)00033-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Yu J, Peñaloza-Vázquez A, Chakrabarty AM, Bender CL. Involvement of the exopolysaccharide alginate in the virulence and epiphytic fitness of Pseudomonas syringae pv. syringae. Mol Microbiol 1999; 33:712-20. [PMID: 10447881 DOI: 10.1046/j.1365-2958.1999.01516.x] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Alginate, a co-polymer of O-acetylated beta-1,4-linked D-mannuronic acid and L-guluronic acid, has been reported to function in the virulence of Pseudomonas syringae, although genetic studies to test this hypothesis have not been undertaken previously. In the present study, we used a genetic approach to evaluate the role of alginate in the pathogenicity of P. syringae pv. syringae 3525, which causes bacterial brown spot on beans. Alginate biosynthesis in strain 3525 was disrupted by recombining Tn5 into algL, which encodes alginate lyase, resulting in 3525.L. Alginate production in 3525.L was restored by the introduction of pSK2 or pAD4033, which contain the alginate biosynthetic gene cluster from P. syringae pv. syringae FF5 or the algA gene from P. aeruginosa respectively. The role of alginate in the epiphytic fitness of strain 3525 was assessed by monitoring the populations of 3525 and 3525.L on tomato, which is not a host for this pathogen. The mutant 3525.L was significantly impaired in its ability to colonize tomato leaves compared with 3525, indicating that alginate functions in the survival of strain 3525 on leaf surfaces. The contribution of alginate to the virulence of strain 3525 was evaluated by comparing the population dynamics and symptom development of 3525 and 3525.L in bean leaves. Although 3525. L retained the ability to form lesions on bean leaves, symptoms were less severe, and the population was significantly reduced in comparison with 3525. These results indicate that alginate contributes to the virulence of P. syringae pv. syringae 3525, perhaps by facilitating colonization or dissemination of the bacterium in planta.
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Affiliation(s)
- J Yu
- 110 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
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Fakhr MK, Peñaloza-Vázquez A, Chakrabarty AM, Bender CL. Regulation of alginate biosynthesis in Pseudomonas syringae pv. syringae. J Bacteriol 1999; 181:3478-85. [PMID: 10348861 PMCID: PMC93816 DOI: 10.1128/jb.181.11.3478-3485.1999] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/1999] [Accepted: 03/24/1999] [Indexed: 11/20/2022] Open
Abstract
Both Pseudomonas aeruginosa and the phytopathogen P. syringae produce the exopolysaccharide alginate. However, the environmental signals that trigger alginate gene expression in P. syringae are different from those in P. aeruginosa with copper being a major signal in P. syringae. In P. aeruginosa, the alternate sigma factor encoded by algT (sigma22) and the response regulator AlgR1 are required for transcription of algD, a gene which encodes a key enzyme in the alginate biosynthetic pathway. In the present study, we cloned and characterized the gene encoding AlgR1 from P. syringae. The deduced amino acid sequence of AlgR1 from P. syringae showed 86% identity to its P. aeruginosa counterpart. Sequence analysis of the region flanking algR1 in P. syringae revealed the presence of argH, algZ, and hemC in an arrangement virtually identical to that reported in P. aeruginosa. An algR1 mutant, P. syringae FF5.32, was defective in alginate production but could be complemented when algR1 was expressed in trans. The algD promoter region in P. syringae (PsalgD) was also characterized and shown to diverge significantly from the algD promoter in P. aeruginosa. Unlike P. aeruginosa, algR1 was not required for the transcription of algD in P. syringae, and PsalgD lacked the consensus sequence recognized by AlgR1. However, both the algD and algR1 upstream regions in P. syringae contained the consensus sequence recognized by sigma22, suggesting that algT is required for transcription of both genes.
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Affiliation(s)
- M K Fakhr
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma 74078, USA
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Hettwer U, Jaeckel FR, Boch J, Meyer M, Rudolph K, Ullrich MS. Cloning, nucleotide sequence, and expression in Escherichia coli of levansucrase genes from the plant pathogens Pseudomonas syringae pv. glycinea and P. syringae pv. phaseolicola. Appl Environ Microbiol 1998; 64:3180-7. [PMID: 9726857 PMCID: PMC106707 DOI: 10.1128/aem.64.9.3180-3187.1998] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plant-pathogenic bacteria produce various extracellular polysaccharides (EPSs) which may function as virulence factors in diseases caused by these bacteria. The EPS levan is synthesized by the extracellular enzyme levansucrase in Pseudomonas syringae, Erwinia amylovora, and other bacterial species. The lsc genes encoding levansucrase from P. syringae pv. glycinea PG4180 and P. syringae pv. phaseolicola NCPPB 1321 were cloned, and their nucleotide sequences were determined. Heterologous expression of the lsc gene in Escherichia coli was found in four and two genomic library clones of strains PG4180 and NCPPB 1321, respectively. A 3. 0-kb PstI fragment common to all six clones conferred levan synthesis on E. coli when further subcloned. Nucleotide sequence analysis revealed a 1,248-bp open reading frame (ORF) derived from PG4180 and a 1,296-bp ORF derived from NCPPB 1321, which were both designated lsc. Both ORFs showed high homology to the E. amylovora and Zymomonas mobilis lsc genes at the nucleic acid and deduced amino acid sequence levels. Levansucrase was not secreted into the supernatant but was located in the periplasmic fraction of E. coli harboring the lsc gene. Expression of lsc was found to be dependent on the vector-based Plac promoter, indicating that the native promoter of lsc was not functional in E. coli. Insertion of an antibiotic resistance cassette in the lsc gene abolished levan synthesis in E. coli. A PCR screening with primers derived from lsc of P. syringae pv. glycinea PG4180 allowed the detection of this gene in a number of related bacteria.
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Affiliation(s)
- U Hettwer
- Institut für Phytopathologie und Pflanzenschutz der Universität Göttingen, 37077 Göttingen, Germany
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Gacesa P. Bacterial alginate biosynthesis--recent progress and future prospects. MICROBIOLOGY (READING, ENGLAND) 1998; 144 ( Pt 5):1133-1143. [PMID: 9611788 DOI: 10.1099/00221287-144-5-1133] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The extracellular polysaccharide alginate has been widely associated with chronic Pseudomonas aeruginosa infections in the cystic fibrosis lung. However, it is clear that alginate biosynthesis is a more widespread phenomenon. Alginate plays a key role as a virulence factor of plant-pathogenic pseudomonads, in the formation of biofilms and with the encystment process of Azotobacter spp.
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Affiliation(s)
- Peter Gacesa
- Faculty of Science and Engineering, Manchester Metropolitan University, John Dalton Extension, Chester Street, Manchester M1 5GD, UK
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Amoroso MJ, Castro GR, Carlino FJ, Romero NC, Hill RTT, Oliver G. Screening of heavy metal-tolerant actinomycetes isolated from the Salí River. J GEN APPL MICROBIOL 1998; 44:129-132. [PMID: 12501279 DOI: 10.2323/jgam.44.129] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Fifty-three strains of actinomycetes resistant to heavy metals were isolated from the Salí River in northwest Argentina. Screening procedures that involve solid and liquid synthetic media containing Cd(2+), Cu(2+), or Hg(2+) allowed the selection of six strains. These strains showed a quantitative sorption of Cd(2+) and Cu(2+) by more than 98% of the initial metal concentrations (0.1, 0.5, and 1.0 mM) tested.
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Affiliation(s)
- Maria J. Amoroso
- Instituto de Microbiologia, Facultad de Bioquimica, Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 491, 4000 Tucumán, Argentina
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Peñaloza-Vázquez A, Kidambi SP, Chakrabarty AM, Bender CL. Characterization of the alginate biosynthetic gene cluster in Pseudomonas syringae pv. syringae. J Bacteriol 1997; 179:4464-72. [PMID: 9226254 PMCID: PMC179280 DOI: 10.1128/jb.179.14.4464-4472.1997] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Alginate, a copolymer of D-mannuronic acid and L-guluronic acid, is produced by a variety of pseudomonads, including Pseudomonas syringae. Alginate biosynthesis has been most extensively studied in P. aeruginosa, and a number of structural and regulatory genes from this species have been cloned and characterized. In the present study, an alginate-defective (Alg-) mutant of P. syringae pv. syringae FF5 was shown to contain a Tn5 insertion in algL, a gene encoding alginate lyase. A cosmid clone designated pSK2 restored alginate production to the algL mutant and was shown to contain homologs of algD, alg8, alg44, algG, algX (alg60), algL, algF, and algA. The order and arrangement of the structural gene cluster were virtually identical to those previously described for P. aeruginosa. Complementation analyses, however, indicated that the structural gene clusters in P. aeruginosa and P. syringae were not functionally interchangeable when expressed from their native promoters. A region upstream of the algD gene in P. syringae pv. syringae was shown to activate the transcription of a promoterless glucuronidase (uidA) gene and indicated that transcription initiated upstream of algD as described for P. aeruginosa. Transcription of the algD promoter from P. syringae FF5 was significantly higher at 32 degrees C than at 18 or 26 degrees C and was stimulated when copper sulfate or sodium chloride was added to the medium. Alginate gene expression was also stimulated by the addition of the nonionic solute sorbitol, indicating that osmolarity is a signal for algD expression in P. syringae FF5.
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Affiliation(s)
- A Peñaloza-Vázquez
- Department of Plant Pathology, Oklahoma State University, Stillwater 74078-3032, USA
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Palmer DA, Bender CL, Sharma SB. Use of Tn5-gusA5 to investigate environmental and nutritional effects on gene expression in the coronatine biosynthetic gene cluster of Pseudomonas syringae pv. glycinea. Can J Microbiol 1997; 43:517-25. [PMID: 9226871 DOI: 10.1139/m97-074] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Pseudomonas syringae pv. glycinea PG4180 produces coronatine (COR), a chlorosis-inducing phytotoxin that consists of the polyketide coronafacic acid (CFA) coupled via an amide bond to the ethylcyclopropyl amino acid coronamic acid (CMA). Both CFA and CMA function as intermediates in the pathway to coronatine, and genes encoding their synthesis have been localized: however, the precise factors that regulate the production of COR and its precursors remain unclear. In the present study, a lambda delivery system for Tn5-gusA5 was developed and used to obtain transcriptional fusions in the COR gene cluster. Selected carbon (fructose and xylose) and amino acid (isoleucine and valine) sources significantly decreased COR biosynthesis at the transcriptional level. Transcriptional activity in the COR gene cluster was temperature dependent with maximal expression at 18-24 degrees C and significantly less expression at 14 and 30 degrees C. Interestingly, changes in osmolarity and the addition of complex carbon and nitrogen sources to the growth medium did not significantly affect COR gene expression, although both factors significantly impacted the quantity of COR produced. These results indicate that multiple factors impact COR production and only some of these directly affect transcription in the COR gene cluster.
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Affiliation(s)
- D A Palmer
- Department of Plant Pathology, Oklahoma State University, Stillwater 74078-3032, USA
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Richau JA, Choquenet D, Fialho AM, Moreira LM, Sá-Correia I. The biosynthesis of the exopolysaccharide gellan results in the decrease of Sphingomonas paucimobilis tolerance to copper. Enzyme Microb Technol 1997. [DOI: 10.1016/s0141-0229(96)00187-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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