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Lorch MG, Valverde C, Agaras BC. Variability in Maize Seed Bacterization and Survival Correlating with Root Colonization by Pseudomonas Isolates with Plant-Probiotic Traits. PLANTS (BASEL, SWITZERLAND) 2024; 13:2130. [PMID: 39124248 DOI: 10.3390/plants13152130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2024] [Revised: 07/29/2024] [Accepted: 07/30/2024] [Indexed: 08/12/2024]
Abstract
Seed treatment with plant growth-promoting bacteria represents the primary strategy to incorporate them into agricultural ecosystems, particularly for crops under extensive management, such as maize. In this study, we evaluated the seed bacterization levels, root colonization patterns, and root competitiveness of a collection of autochthonous Pseudomonas isolates that have demonstrated several plant-probiotic abilities in vitro. Our findings indicate that the seed bacterization level, both with and without the addition of various protectants, is specific to each Pseudomonas strain, including their response to seed pre-hydration. Bacterization kinetics revealed that while certain isolates persisted on seed surfaces for up to 4 days post-inoculation (dpi), others experienced a rapid decline in viability after 1 or 2 dpi. The observed differences in seed bacterization levels were consistent with the root colonization densities observed through confocal microscopy analysis, and with root competitiveness quantified via selective plate counts. Notably, isolates P. protegens RBAN4 and P. chlororaphis subsp. aurantiaca SMMP3 demonstrated effective competition with the natural microflora for colonizing the maize rhizosphere and both promoted shoot and root biomass production in maize assessed at the V3 grown stage. Conversely, P. donghuensis SVBP6 was detected at very low levels in the maize rhizosphere, but still exhibited a positive effect on plant parameters, suggesting a growth-stimulatory effect during the early stages of plant development. In conclusion, there is a considerable strain-specific variability in the maize seed bacterization and survival capacities of Pseudomonas isolates with plant-probiotic traits, with a correlation in their root competitiveness under natural conditions. This variability must be understood to optimize their adoption as inputs for the agricultural system. Our experimental approach emphasizes the critical importance of tailoring seed bacterization treatments for each inoculant candidate, including the selection and incorporation of protective substances. It should not be assumed that all bacterial cells exhibit a similar performance.
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Affiliation(s)
- Melani G Lorch
- Laboratory of Physiology and Genetics of Plant Probiotic Bacteria (LFGBBP), Centre of Biochemistry and Microbiology of Soils, National University of Quilmes, Bernal B1876BXD, Argentina
- National Scientific and Technical Research Council (CONICET), Buenos Aires C1425FQB, Argentina
| | - Claudio Valverde
- Laboratory of Physiology and Genetics of Plant Probiotic Bacteria (LFGBBP), Centre of Biochemistry and Microbiology of Soils, National University of Quilmes, Bernal B1876BXD, Argentina
- National Scientific and Technical Research Council (CONICET), Buenos Aires C1425FQB, Argentina
| | - Betina C Agaras
- Laboratory of Physiology and Genetics of Plant Probiotic Bacteria (LFGBBP), Centre of Biochemistry and Microbiology of Soils, National University of Quilmes, Bernal B1876BXD, Argentina
- National Scientific and Technical Research Council (CONICET), Buenos Aires C1425FQB, Argentina
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2
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Peoples LM, Isanta-Navarro J, Bras B, Hand BK, Rosenzweig F, Elser JJ, Church MJ. Physiology, fast and slow: bacterial response to variable resource stoichiometry and dilution rate. mSystems 2024:e0077024. [PMID: 38980051 DOI: 10.1128/msystems.00770-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Accepted: 06/19/2024] [Indexed: 07/10/2024] Open
Abstract
Microorganisms grow despite imbalances in the availability of nutrients and energy. The biochemical and elemental adjustments that bacteria employ to sustain growth when these resources are suboptimal are not well understood. We assessed how Pseudomonas putida KT2440 adjusts its physiology at differing dilution rates (to approximate growth rates) in response to carbon (C), nitrogen (N), and phosphorus (P) stress using chemostats. Cellular elemental and biomolecular pools were variable in response to different limiting resources at a slow dilution rate of 0.12 h-1, but these pools were more similar across treatments at a faster rate of 0.48 h-1. At slow dilution rates, limitation by P and C appeared to alter cell growth efficiencies as reflected by changes in cellular C quotas and rates of oxygen consumption, both of which were highest under P- and lowest under C- stress. Underlying these phenotypic changes was differential gene expression of terminal oxidases used for ATP generation that allows for increased energy generation efficiency. In all treatments under fast dilution rates, KT2440 formed aggregates and biofilms, a physiological response that hindered an accurate assessment of growth rate, but which could serve as a mechanism that allows cells to remain in conditions where growth is favorable. Our findings highlight the ways that microorganisms dynamically adjust their physiology under different resource supply conditions, with distinct mechanisms depending on the limiting resource at slow growth and convergence toward an aggregative phenotype with similar compositions under conditions that attempt to force fast growth. IMPORTANCE All organisms experience suboptimal growth conditions due to low nutrient and energy availability. Their ability to survive and reproduce under such conditions determines their evolutionary fitness. By imposing suboptimal resource ratios under different dilution rates on the model organism Pseudomonas putida KT2440, we show that this bacterium dynamically adjusts its elemental composition, morphology, pools of biomolecules, and levels of gene expression. By examining the ability of bacteria to respond to C:N:P imbalance, we can begin to understand how stoichiometric flexibility manifests at the cellular level and impacts the flow of energy and elements through ecosystems.
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Affiliation(s)
- Logan M Peoples
- Flathead Lake Biological Station, University of Montana, Polson, Montana, USA
| | - Jana Isanta-Navarro
- Flathead Lake Biological Station, University of Montana, Polson, Montana, USA
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Benedicta Bras
- Flathead Lake Biological Station, University of Montana, Polson, Montana, USA
| | - Brian K Hand
- Flathead Lake Biological Station, University of Montana, Polson, Montana, USA
| | - Frank Rosenzweig
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - James J Elser
- Flathead Lake Biological Station, University of Montana, Polson, Montana, USA
| | - Matthew J Church
- Flathead Lake Biological Station, University of Montana, Polson, Montana, USA
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3
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Molina-Henares MA, Ramos-González MI, Rinaldo S, Espinosa-Urgel M. Gene expression reprogramming of Pseudomonas alloputida in response to arginine through the transcriptional regulator ArgR. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001449. [PMID: 38511653 PMCID: PMC10963909 DOI: 10.1099/mic.0.001449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 03/07/2024] [Indexed: 03/22/2024]
Abstract
Different bacteria change their life styles in response to specific amino acids. In Pseudomonas putida (now alloputida) KT2440, arginine acts both as an environmental and a metabolic indicator that modulates the turnover of the intracellular second messenger c-di-GMP, and expression of biofilm-related genes. The transcriptional regulator ArgR, belonging to the AraC/XylS family, is key for the physiological reprogramming in response to arginine, as it controls transport and metabolism of the amino acid. To further expand our knowledge on the roles of ArgR, a global transcriptomic analysis of KT2440 and a null argR mutant growing in the presence of arginine was carried out. Results indicate that this transcriptional regulator influences a variety of cellular functions beyond arginine metabolism and transport, thus widening its regulatory role. ArgR acts as positive or negative modulator of the expression of several metabolic routes and transport systems, respiratory chain and stress response elements, as well as biofilm-related functions. The partial overlap between the ArgR regulon and those corresponding to the global regulators RoxR and ANR is also discussed.
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Affiliation(s)
- María Antonia Molina-Henares
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, CSIC. Profesor Albareda, 1. Granada 18008, Spain
| | - María Isabel Ramos-González
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, CSIC. Profesor Albareda, 1. Granada 18008, Spain
| | - Serena Rinaldo
- Laboratory Affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti - Department of Biochemical Sciences “A. Rossi Fanelli”, Sapienza University of Rome, Rome, Italy
| | - Manuel Espinosa-Urgel
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, CSIC. Profesor Albareda, 1. Granada 18008, Spain
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4
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Blanco-Romero E, Garrido-Sanz D, Durán D, Rybtke M, Tolker-Nielsen T, Redondo-Nieto M, Rivilla R, Martín M. Role of extracellular matrix components in biofilm formation and adaptation of Pseudomonas ogarae F113 to the rhizosphere environment. Front Microbiol 2024; 15:1341728. [PMID: 38333580 PMCID: PMC10850567 DOI: 10.3389/fmicb.2024.1341728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 01/11/2024] [Indexed: 02/10/2024] Open
Abstract
Regulating the transition of bacteria from motile to sessile lifestyles is crucial for their ability to compete effectively in the rhizosphere environment. Pseudomonas are known to rely on extracellular matrix (ECM) components for microcolony and biofilm formation, allowing them to adapt to a sessile lifestyle. Pseudomonas ogarae F113 possesses eight gene clusters responsible for the production of ECM components. These gene clusters are tightly regulated by AmrZ, a major transcriptional regulator that influences the cellular levels of c-di-GMP. The AmrZ-mediated transcriptional regulation of ECM components is primarily mediated by the signaling molecule c-di-GMP and the flagella master regulator FleQ. To investigate the functional role of these ECM components in P. ogarae F113, we performed phenotypic analyses using mutants in genes encoding these ECM components. These analyses included assessments of colony morphology, dye-staining, static attachment to abiotic surfaces, dynamic biofilm formation on abiotic surfaces, swimming motility, and competitive colonization assays of the rhizosphere. Our results revealed that alginate and PNAG polysaccharides, along with PsmE and the fimbrial low molecular weight protein/tight adherence (Flp/Tad) pilus, are the major ECM components contributing to biofilm formation. Additionally, we found that the majority of these components and MapA are needed for a competitive colonization of the rhizosphere in P. ogarae F113.
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Affiliation(s)
- Esther Blanco-Romero
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
| | - Daniel Garrido-Sanz
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - David Durán
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
| | - Morten Rybtke
- Costerton Biofilm Center, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Tim Tolker-Nielsen
- Costerton Biofilm Center, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Miguel Redondo-Nieto
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
| | - Rafael Rivilla
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
| | - Marta Martín
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
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5
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Costa-Gutierrez SB, Raimondo EE, Vincent PA, de Cristóbal RE. Importance of biofilm formation for promoting plant growth under salt stress in Pseudomonas putida KT2440. J Basic Microbiol 2023; 63:1219-1232. [PMID: 37537345 DOI: 10.1002/jobm.202300215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 06/20/2023] [Accepted: 07/12/2023] [Indexed: 08/05/2023]
Abstract
An underutilized experimental design was employed to isolate adapted mutants of the model bacterium Pseudomonas putida KT2440. The design involved subjecting a random pool of mini-Tn5 mutants of P. putida KT2440 to multiple rounds of selection in the rhizosphere of soybean plants irrigated with a NaCl solution. The isolated adapted mutants, referred to as MutAd, exhibited a mutation in the gene responsible for encoding the membrane-binding protein LapA, which plays a role in the initial stages of biofilm formation on abiotic surfaces. Two MutAd bacteria, MutAd160 and MutAd185, along with a lapA deletion mutant, were selected for further investigation to examine the impact of this gene on salt tolerance, rhizosphere fitness, production of extracellular polymeric substances (EPS), and promotion of plant growth. Despite the mutants' inability to form biofilms, they were able to attach to soybean seeds and roots. The MutAd bacteria demonstrated an elevated production of EPS when cultivated under saline conditions, which likely compensated for the absence of biofilm formation. MutAd185 bacteria exhibited enhanced root attachment and promoted the growth of soybean plants in slightly saline soils. The proposed experimental design holds promise for expediting bacterial adaptation to the rhizosphere of plants under specific environmental conditions, identifying genetic mutations that enhance bacterial fitness in those conditions, and thereby increasing their capacity to promote plant growth.
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Affiliation(s)
- Stefanie Bernardette Costa-Gutierrez
- Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) e Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Miguel de Tucumán, Tucumán, Argentina
| | - Enzo Emanuel Raimondo
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI-CONICET), Avenida Belgrano y Pasaje Caseros, San Miguel de Tucumán, Tucumán, Argentina
- Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Miguel de Tucumán, Tucumán, Argentina
| | - Paula Andrea Vincent
- Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) e Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Miguel de Tucumán, Tucumán, Argentina
| | - Ricardo Ezequiel de Cristóbal
- Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) e Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Miguel de Tucumán, Tucumán, Argentina
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Agaras BC, Grossi CEM, Ulloa RM. Unveiling the Secrets of Calcium-Dependent Proteins in Plant Growth-Promoting Rhizobacteria: An Abundance of Discoveries Awaits. PLANTS (BASEL, SWITZERLAND) 2023; 12:3398. [PMID: 37836138 PMCID: PMC10574481 DOI: 10.3390/plants12193398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 09/20/2023] [Accepted: 09/22/2023] [Indexed: 10/15/2023]
Abstract
The role of Calcium ions (Ca2+) is extensively documented and comprehensively understood in eukaryotic organisms. Nevertheless, emerging insights, primarily derived from studies on human pathogenic bacteria, suggest that this ion also plays a pivotal role in prokaryotes. In this review, our primary focus will be on unraveling the intricate Ca2+ toolkit within prokaryotic organisms, with particular emphasis on its implications for plant growth-promoting rhizobacteria (PGPR). We undertook an in silico exploration to pinpoint and identify some of the proteins described in the existing literature, including prokaryotic Ca2+ channels, pumps, and exchangers that are responsible for regulating intracellular Calcium concentration ([Ca2+]i), along with the Calcium-binding proteins (CaBPs) that play a pivotal role in sensing and transducing this essential cation. These investigations were conducted in four distinct PGPR strains: Pseudomonas chlororaphis subsp. aurantiaca SMMP3, P. donghuensis SVBP6, Pseudomonas sp. BP01, and Methylobacterium sp. 2A, which have been isolated and characterized within our research laboratories. We also present preliminary experimental data to evaluate the influence of exogenous Ca2+ concentrations ([Ca2+]ex) on the growth dynamics of these strains.
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Affiliation(s)
- Betina Cecilia Agaras
- Laboratory of Physiology and Genetics of Plant Probiotic Bacteria (LFGBBP), Centre of Biochemistry and Microbiology of Soils, National University of Quilmes, Bernal B1876BXD, Argentina
- National Scientific and Technical Research Council (CONICET), Buenos Aires C1425FQB, Argentina;
| | - Cecilia Eugenia María Grossi
- National Scientific and Technical Research Council (CONICET), Buenos Aires C1425FQB, Argentina;
- Laboratory of Plant Signal Transduction, Institute of Genetic Engineering and Molecular Biology (INGEBI), National Scientific and Technical Research Council (CONICET), Buenos Aires C1425FQB, Argentina
| | - Rita María Ulloa
- National Scientific and Technical Research Council (CONICET), Buenos Aires C1425FQB, Argentina;
- Laboratory of Plant Signal Transduction, Institute of Genetic Engineering and Molecular Biology (INGEBI), National Scientific and Technical Research Council (CONICET), Buenos Aires C1425FQB, Argentina
- Biochemistry Department, Faculty of Exact and Natural Sciences, University of Buenos Aires (FCEN-UBA), Buenos Aires C1428EGA, Argentina
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7
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Espinosa-Urgel M, Ramos-González MI. Becoming settlers: Elements and mechanisms for surface colonization by Pseudomonas putida. Environ Microbiol 2023; 25:1575-1593. [PMID: 37045787 DOI: 10.1111/1462-2920.16385] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 03/31/2023] [Indexed: 04/14/2023]
Abstract
Pseudomonads are considered to be among the most widespread culturable bacteria in mesophilic environments. The evolutive success of Pseudomonas species can be attributed to their metabolic versatility, in combination with a set of additional functions that enhance their ability to colonize different niches. These include the production of secondary metabolites involved in iron acquisition or having a detrimental effect on potential competitors, different types of motility, and the capacity to establish and persist within biofilms. Although biofilm formation has been extensively studied using the opportunistic pathogen Pseudomonas aeruginosa as a model organism, a significant body of knowledge is also becoming available for non-pathogenic Pseudomonas. In this review, we focus on the mechanisms that allow Pseudomonas putida to colonize biotic and abiotic surfaces and adapt to sessile life, as a relevant persistence strategy in the environment. This species is of particular interest because it includes plant-beneficial strains, in which colonization of plant surfaces may be relevant, and strains used for environmental and biotechnological applications, where the design and functionality of biofilm-based bioreactors, for example, also have to take into account the efficiency of bacterial colonization of solid surfaces. This work reviews the current knowledge of mechanistic and regulatory aspects of biofilm formation by P. putida and pinpoints the prospects in this field.
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Affiliation(s)
- Manuel Espinosa-Urgel
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, Granada, Spain
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8
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Bhattacharyya A, Mavrodi O, Bhowmik N, Weller D, Thomashow L, Mavrodi D. Bacterial biofilms as an essential component of rhizosphere plant-microbe interactions. METHODS IN MICROBIOLOGY 2023; 53:3-48. [PMID: 38415193 PMCID: PMC10898258 DOI: 10.1016/bs.mim.2023.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Affiliation(s)
- Ankita Bhattacharyya
- School of Biological, Environmental and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Olga Mavrodi
- School of Biological, Environmental and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Niladri Bhowmik
- School of Biological, Environmental and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - David Weller
- USDA-ARS Wheat Health, Genetics and Quality Research Unit, Pullman, WA, United States
| | - Linda Thomashow
- USDA-ARS Wheat Health, Genetics and Quality Research Unit, Pullman, WA, United States
| | - Dmitri Mavrodi
- School of Biological, Environmental and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
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9
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Exploring the Role of Salicylic Acid in Regulating the Colonization Ability of Bacillus subtilis 26D in Potato Plants and Defense against Phytophthora infestans. INTERNATIONAL JOURNAL OF PLANT BIOLOGY 2023. [DOI: 10.3390/ijpb14010020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023] Open
Abstract
Plant colonization by endophytic bacteria is mediated by different biomolecules that cause dynamic changes in gene expression of both bacteria and plant. Phytohormones, in particular, salicylic acid, play a key role in the regulation of endophytic colonization and diversity of bacteria in methaphytobiome. For the first time it was found that salicylic acid influenced motility in biofilms and transcription of the surfactin synthetase gene of the endophytic strain Bacillus subtilis 26D in vitro. Treatment of Solanum tuberosum plants with salicylic acid, along with B. subtilis 26D, increased the number of endophytic cells of bacteria in potato internal tissues and level of transcripts of bacterial surfactin synthetase gene and decreased transcription of plant PR genes on the stage of colonisation with endophytes. Thus, the production of surfactin plays an important role in endophytic colonization of plants, and salicylic acid has an ability to influence this mechanism. Here we firstly show that plants treated with salicylic acid and B. subtilis 26D showed enhanced resistance to the late blight pathogen Phytophthora infestans, which was accompanied by increase in transcriptional activity of plant PR-genes and bacterial surfactin synthetase gene after pathogen inoculation. Therefore, it is suggested that salicylic acid can modulate physiological status of the whole plant–endophyte system and improve biocontrol potential of endophytic strains.
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10
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Elpers L, Lüken L, Lange F, Hensel M. Factors Required for Adhesion of Salmonella enterica Serovar Typhimurium to Lactuca sativa (Lettuce). Microbiol Spectr 2023; 11:e0343622. [PMID: 36533955 PMCID: PMC9927257 DOI: 10.1128/spectrum.03436-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 11/29/2022] [Indexed: 12/23/2022] Open
Abstract
Salmonella enterica serovar Typhimurium is a major cause of foodborne gastroenteritis. Recent outbreaks of infections by S. enterica serovar Typhimurium are often associated with non-animal-related food, i.e., vegetables, fruits, herbs, sprouts, and nuts. One main problem related to the consumption of fresh produce is the minimal processing, especially for leafy green salads. In this study, we focused on butterhead lettuce (Lactuca sativa) to which S. enterica serovar Typhimurium adheres at higher rates compared to Valerianella locusta, resulting in prolonged persistence. Here, we systematically analyzed factors contributing to adhesion of S. enterica serovar Typhimurium to L. sativa leaves. Application of a reductionist, synthetic approach, including the controlled surface expression of specific adhesive structures of S. enterica serovar Typhimurium, one at a time, enabled the identification of relevant fimbrial and nonfimbrial adhesins, the O-antigen of lipopolysaccharide, the flagella, and chemotaxis being involved in binding to L. sativa leaves. The analyses revealed contributions of Lpf fimbriae, Sti fimbriae, autotransported adhesin MisL, T1SS-secreted BapA, intact lipopolysaccharide (LPS), and flagella-mediated motility to adhesion of S. enterica serovar Typhimurium to L. sativa leaves. In addition, we identified BapA as a potential adhesin involved in binding to V. locusta and L. sativa leaf surfaces. IMPORTANCE The number of produce-associated outbreaks by gastrointestinal pathogens is increasing and underlines the relevance to human health. The mechanisms involved in the colonization of, persistence on, and transmission by, fresh produce are poorly understood. Here, we investigated the contribution of adhesive factors of S. enterica serovar Typhimurium in the initial phase of plant colonization, i.e., the binding to the plant surface. We used the previously established reductionist, synthetic approach to identify factors that contribute to the surface binding of S. enterica serovar Typhimurium to leaves of L. sativa by expressing all known adhesive structures by remote control expression system.
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Affiliation(s)
- Laura Elpers
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Lena Lüken
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Fabio Lange
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Michael Hensel
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
- Center for Cellular Nanoanalytics (CellNanOs), Universität Osnabrück, Osnabrück, Germany
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11
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Illuminating the signalomics of microbial biofilm on plant surfaces. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2022. [DOI: 10.1016/j.bcab.2022.102537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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12
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Bunyoo C, Roongsattham P, Khumwan S, Phonmakham J, Wonnapinij P, Thamchaipenet A. Dynamic Alteration of Microbial Communities of Duckweeds from Nature to Nutrient-Deficient Condition. PLANTS (BASEL, SWITZERLAND) 2022; 11:plants11212915. [PMID: 36365369 PMCID: PMC9658847 DOI: 10.3390/plants11212915] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 10/24/2022] [Accepted: 10/25/2022] [Indexed: 06/12/2023]
Abstract
Duckweeds live with complex assemblages of microbes as holobionts that play an important role in duckweed growth and phytoremediation ability. In this study, the structure and diversity of duckweed-associated bacteria (DAB) among four duckweed subtypes under natural and nutrient-deficient conditions were investigated using V3-V4 16S rRNA amplicon sequencing. High throughput sequencing analysis indicated that phylum Proteobacteria was predominant in across duckweed samples. A total of 24 microbial genera were identified as a core microbiome that presented in high abundance with consistent proportions across all duckweed subtypes. The most abundant microbes belonged to the genus Rhodobacter, followed by other common DAB, including Acinetobacter, Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, and Pseudomonas. After nutrient-deficient stress, diversity of microbial communities was significantly deceased. However, the relative abundance of Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, Pelomonas, Roseateles and Novosphingobium were significantly enhanced in stressed duckweeds. Functional prediction of the metagenome data displayed the relative abundance of essential pathways involved in DAB colonization, such as bacterial motility and biofilm formation, as well as biodegradable ability, such as benzoate degradation and nitrogen metabolism, were significantly enriched under stress condition. The findings improve the understanding of the complexity of duckweed microbiomes and facilitate the establishment of a stable microbiome used for co-cultivation with duckweeds for enhancement of biomass and phytoremediation under environmental stress.
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Affiliation(s)
- Chakrit Bunyoo
- Interdisciplinary Graduate Program in Bioscience, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
- Duckweed Holobiont Resource & Research Center (DHbRC), Kasetsart University, Bangkok 10900, Thailand
| | - Peerapat Roongsattham
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
- Duckweed Holobiont Resource & Research Center (DHbRC), Kasetsart University, Bangkok 10900, Thailand
| | - Sirikorn Khumwan
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
- Duckweed Holobiont Resource & Research Center (DHbRC), Kasetsart University, Bangkok 10900, Thailand
| | - Juthaporn Phonmakham
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
- Duckweed Holobiont Resource & Research Center (DHbRC), Kasetsart University, Bangkok 10900, Thailand
| | - Passorn Wonnapinij
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
- Duckweed Holobiont Resource & Research Center (DHbRC), Kasetsart University, Bangkok 10900, Thailand
- Omics Center for Agriculture, Bioresource, Food and Health Kasetsart University (OmiKU), Bangkok 10900, Thailand
| | - Arinthip Thamchaipenet
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
- Duckweed Holobiont Resource & Research Center (DHbRC), Kasetsart University, Bangkok 10900, Thailand
- Omics Center for Agriculture, Bioresource, Food and Health Kasetsart University (OmiKU), Bangkok 10900, Thailand
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13
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Santamaría‐Hernando S, De Bruyne L, Höfte M, Ramos‐González M. Improvement of fitness and biocontrol properties of
Pseudomonas putida
via an extracellular heme peroxidase. Microb Biotechnol 2022; 15:2652-2666. [PMID: 35986900 PMCID: PMC9518985 DOI: 10.1111/1751-7915.14123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 07/18/2022] [Indexed: 11/27/2022] Open
Abstract
The extracellular 373‐kDa PehA heme peroxidase of Pseudomonas putida KT2440 has two enzymatic domains which depend on heme cofactor for their peroxidase activity. A null pehA mutant was generated to examine the impact of PehA in rhizosphere colonization competence and the induction of plant systemic resistance (ISR). This mutant was not markedly hampered in colonization efficiency. However, increase in pehA dosage enhanced colonization fitness about 30 fold in the root and 900 fold in the root apex. In vitro assays with purified His‐tagged enzymatic domains of PehA indicated that heme‐dependent peroxidase activity was required for the enhancement of root tip colonization. Evaluation of live/dead cells confirmed that overexpression of pehA had a positive effect on bacterial cell viability. Following root colonization of rice plants by KT2440 strain, the incidence of rice blast caused by Magnaporthe oryzae was reduced by 65% and the severity of this disease was also diminished in comparison to non‐treated plants. An increase in the pehA dosage was also beneficial for the control of rice blast as compared with gene inactivation. The results suggest that PehA helps P. putida to cope with the plant‐imposed oxidative stress leading to enhanced colonization ability and concomitant ISR‐elicitation.
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Affiliation(s)
- Saray Santamaría‐Hernando
- Department of Environmental Protection Estación Experimental de Zaidín‐Consejo Superior de Investigaciones Científicas (CSIC) Granada Spain
- Laboratory of Phytopathology, Department of Plants and Crops, Faculty of Bioscience Engineering Ghent University Ghent Belgium
| | - Lieselotte De Bruyne
- Laboratory of Phytopathology, Department of Plants and Crops, Faculty of Bioscience Engineering Ghent University Ghent Belgium
| | - Monica Höfte
- Laboratory of Phytopathology, Department of Plants and Crops, Faculty of Bioscience Engineering Ghent University Ghent Belgium
| | - María‐Isabel Ramos‐González
- Department of Environmental Protection Estación Experimental de Zaidín‐Consejo Superior de Investigaciones Científicas (CSIC) Granada Spain
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14
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Rani S, Kumar P, Dahiya P, Maheshwari R, Dang AS, Suneja P. Endophytism: A Multidimensional Approach to Plant-Prokaryotic Microbe Interaction. Front Microbiol 2022; 13:861235. [PMID: 35633681 PMCID: PMC9135327 DOI: 10.3389/fmicb.2022.861235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 03/11/2022] [Indexed: 11/20/2022] Open
Abstract
Plant growth and development are positively regulated by the endophytic microbiome via both direct and indirect perspectives. Endophytes use phytohormone production to promote plant health along with other added benefits such as nutrient acquisition, nitrogen fixation, and survival under abiotic and biotic stress conditions. The ability of endophytes to penetrate the plant tissues, reside and interact with the host in multiple ways makes them unique. The common assumption that these endophytes interact with plants in a similar manner as the rhizospheric bacteria is a deterring factor to go deeper into their study, and more focus was on symbiotic associations and plant–pathogen reactions. The current focus has shifted on the complexity of relationships between host plants and their endophytic counterparts. It would be gripping to inspect how endophytes influence host gene expression and can be utilized to climb the ladder of “Sustainable agriculture.” Advancements in various molecular techniques have provided an impetus to elucidate the complexity of endophytic microbiome. The present review is focused on canvassing different aspects concerned with the multidimensional interaction of endophytes with plants along with their application.
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Affiliation(s)
- Simran Rani
- Plant Microbe Interaction Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, India
| | - Pradeep Kumar
- Plant Microbe Interaction Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, India
| | - Priyanka Dahiya
- Plant Microbe Interaction Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, India
| | - Rajat Maheshwari
- Plant Microbe Interaction Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, India
| | - Amita Suneja Dang
- Centre for Medical Biotechnology, Maharshi Dayanand University, Rohtak, India
| | - Pooja Suneja
- Plant Microbe Interaction Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, India
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15
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Puhm M, Hendrikson J, Kivisaar M, Teras R. Pseudomonas putida Biofilm Depends on the vWFa-Domain of LapA in Peptides-Containing Growth Medium. Int J Mol Sci 2022; 23:ijms23115898. [PMID: 35682576 PMCID: PMC9180339 DOI: 10.3390/ijms23115898] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/20/2022] [Accepted: 05/23/2022] [Indexed: 01/27/2023] Open
Abstract
The biofilm of Pseudomonas putida is complexly regulated by several intercellular and extracellular factors. The cell surface adhesin LapA of this bacterium is a central factor for the biofilm and, consequently, the regulation of lapA expression, for example, by Fis. It has been recently shown that peptides in growth media enhance the formation of P. putida biofilm, but not as a source of carbon and nitrogen. Moreover, the peptide-dependent biofilm appeared especially clearly in the fis-overexpression strain, which also has increased LapA. Therefore, we investigate here whether there is a relationship between LapA and peptide-dependent biofilm. The P. putida strains with inducible lapA expression and LapA without the vWFa domain, which is described as a domain similar to von Willebrand factor domain A, were constructed. Thereafter, the biofilm of these strains was assessed in growth media containing extracellular peptides in the shape of tryptone and without it. We show that the vWFa domain in LapA is necessary for biofilm enhancement by the extracellular peptides in the growth medium. The importance of vWFa in LapA was particularly evident for the fis-overexpression strain F15. The absence of the vWFa domain diminished the positive effect of Fis on the F15 biofilm.
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16
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Costa-Gutierrez SB, Adler C, Espinosa-Urgel M, de Cristóbal RE. Pseudomonas putida and its close relatives: mixing and mastering the perfect tune for plants. Appl Microbiol Biotechnol 2022; 106:3351-3367. [PMID: 35488932 PMCID: PMC9151500 DOI: 10.1007/s00253-022-11881-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 03/09/2022] [Accepted: 03/10/2022] [Indexed: 11/16/2022]
Abstract
Abstract Plant growth–promoting rhizobacteria (PGPR) are a group of microorganisms of utmost interest in agricultural biotechnology for their stimulatory and protective effects on plants. Among the various PGPR species, some Pseudomonas putida strains combine outstanding traits such as phytohormone synthesis, nutrient solubilization, adaptation to different stress conditions, and excellent root colonization ability. In this review, we summarize the state of the art and the most relevant findings related to P. putida and its close relatives as PGPR, and we have compiled a detailed list of P. putida sensu stricto, sensu lato, and close relative strains that have been studied for their plant growth–promoting characteristics. However, the mere in vitro analysis of these characteristics does not guarantee correct plant performance under in vivo or field conditions. Therefore, the importance of studying adhesion and survival in the rhizosphere, as well as responses to environmental factors, is emphasized. Although numerous strains of this species have shown good performance in field trials, their use in commercial products is still very limited. Thus, we also analyze the opportunities and challenges related to the formulation and application of bioproducts based on these bacteria. Key points •The mini-review updates the knowledge on Pseudomonas putida as a PGPR. • Some rhizosphere strains are able to improve plant growth under stress conditions. • The metabolic versatility of this species encourages the development of a bioproduct.
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Affiliation(s)
- Stefanie Bernardette Costa-Gutierrez
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI-CONICET), Avenida Belgrano Y Pasaje Caseros, 4000, San Miguel de Tucumán, Tucumán, Argentina
| | - Conrado Adler
- Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) E Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, 461, 4000 San Miguel de Tucumán, Chacabuco, Tucumán, Argentina
| | - Manuel Espinosa-Urgel
- Department of Environmental Protection, Estación Experimental del Zaidín, CSIC, Profesor Albareda 1, 18008, Granada, Spain
| | - Ricardo Ezequiel de Cristóbal
- Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) E Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, 461, 4000 San Miguel de Tucumán, Chacabuco, Tucumán, Argentina.
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17
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Tryptone in Growth Media Enhances Pseudomonas putida Biofilm. Microorganisms 2022; 10:microorganisms10030618. [PMID: 35336191 PMCID: PMC8954664 DOI: 10.3390/microorganisms10030618] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/10/2022] [Accepted: 03/11/2022] [Indexed: 11/24/2022] Open
Abstract
Extracellular factors and growth conditions can affect the formation and development of bacterial biofilms. The biofilm of Pseudomonas putida has been studied for decades, but so far, little attention has been paid to the components of the medium that may affect the biofilm development in a closed system. It is known that Fis strongly enhances biofilm in complete LB medium. However, this is not the case in the defined M9 medium, which led us to question why the bacterium behaves differently in these two media. Detailed analysis of the individual medium components revealed that tryptone as the LB proteinaceous component maintains biofilm in its older stages. Although the growth parameters of planktonic cells were similar in the media containing tryptone or an equivalent concentration of amino acids, only the tryptone had a positive effect on the mature biofilm of the wild type strain of P. putida. Thus, the peptides in the environment may influence mature biofilm as a structural factor and not only as an energy source. Testing the effect of other biopolymers on biofilm formation showed variable results even for polymers with a similar charge, indicating that biopolymers can affect P. putida biofilm through a number of bacterial factors.
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18
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Role of the Transcriptional Regulator ArgR in the Connection between Arginine Metabolism and c-di-GMP Signaling in Pseudomonas putida. Appl Environ Microbiol 2022; 88:e0006422. [PMID: 35254100 DOI: 10.1128/aem.00064-22] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The second messenger cyclic di-GMP (c-di-GMP) is a key molecule that controls different physiological and behavioral processes in many bacteria, including motile-to-sessile lifestyle transitions. Although the external stimuli that modulate cellular c-di-GMP contents are not fully characterized, there is growing evidence that certain amino acids act as environmental cues for c-di-GMP turnover. In the plant-beneficial bacterium Pseudomonas putida KT2440, both arginine biosynthesis and uptake influence second messenger contents and the associated phenotypes. To further understand this connection, we have analyzed the role of ArgR, which in different bacteria is the master transcriptional regulator of arginine metabolism but had not been characterized in P. putida. The results show that ArgR controls arginine biosynthesis and transport, and an argR-null mutant grows poorly with arginine as the sole carbon or nitrogen source and also displays increased biofilm formation and reduced surface motility. Modulation of c-di-GMP levels by exogenous arginine requires ArgR. The expression of certain biofilm matrix components, namely, the adhesin LapF and the exopolysaccharide Pea, as well as the diguanylate cyclase CfcR is influenced by ArgR, likely through the alternative sigma factor RpoS. Our data indicate the existence of a regulatory feedback loop between ArgR and c-di-GMP mediated by FleQ. IMPORTANCE Identifying the molecular mechanisms by which metabolic and environmental signals influence the turnover of the second messenger c-di-GMP is key to understanding the regulation of bacterial lifestyles. The results presented here point at the transcriptional regulator ArgR as a central node linking arginine metabolism and c-di-GMP signaling and indicate the existence of a complex balancing mechanism that connects cellular arginine contents and second messenger levels, ultimately controlling the lifestyles of Pseudomonas putida.
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19
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Knights HE, Jorrin B, Haskett TL, Poole PS. Deciphering bacterial mechanisms of root colonization. ENVIRONMENTAL MICROBIOLOGY REPORTS 2021; 13:428-444. [PMID: 33538402 PMCID: PMC8651005 DOI: 10.1111/1758-2229.12934] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 05/07/2023]
Abstract
Bacterial colonization of the rhizosphere is critical for the establishment of plant-bacteria interactions that represent a key determinant of plant health and productivity. Plants influence bacterial colonization primarily through modulating the composition of their root exudates and mounting an innate immune response. The outcome is a horizontal filtering of bacteria from the surrounding soil, resulting in a gradient of reduced bacterial diversity coupled with a higher degree of bacterial specialization towards the root. Bacteria-bacteria interactions (BBIs) are also prevalent in the rhizosphere, influencing bacterial persistence and root colonization through metabolic exchanges, secretion of antimicrobial compounds and other processes. Traditionally, bacterial colonization has been examined under sterile laboratory conditions that mitigate the influence of BBIs. Using simplified synthetic bacterial communities combined with microfluidic imaging platforms and transposon mutagenesis screening approaches, we are now able to begin unravelling the molecular mechanisms at play during the early stages of root colonization. This review explores the current state of knowledge regarding bacterial root colonization and identifies key tools for future exploration.
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Affiliation(s)
| | - Beatriz Jorrin
- Department of Plant SciencesUniversity of OxfordOxfordOX1 3RBUK
| | | | - Philip S. Poole
- Department of Plant SciencesUniversity of OxfordOxfordOX1 3RBUK
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20
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Ali S, Khan N. Delineation of mechanistic approaches employed by plant growth promoting microorganisms for improving drought stress tolerance in plants. Microbiol Res 2021; 249:126771. [PMID: 33930840 DOI: 10.1016/j.micres.2021.126771] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 04/01/2021] [Accepted: 04/17/2021] [Indexed: 11/24/2022]
Abstract
Drought stress is expected to increase in intensity, frequency, and duration in many parts of the world, with potential negative impacts on plant growth and productivity. The plants have evolved complex physiological and biochemical mechanisms to respond and adjust to water-deficient environments. The physiological and biochemical mechanisms associated with water-stress tolerance and water-use efficiency have been extensively studied. Besides these adaptive and mitigating strategies, the plant growth-promoting rhizobacteria (PGPR) play a significant role in alleviating plant drought stress. These beneficial microorganisms colonize the endo-rhizosphere/rhizosphere of plants and enhance drought tolerance. The common mechanism by which these microorganisms improve drought tolerance included the production of volatile compounds, phytohormones, siderophores, exopolysaccharides, 1-aminocyclopropane-1-carboxylate deaminase (ACC deaminase), accumulation of antioxidant, stress-induced metabolites such as osmotic solutes proline, alternation in leaf and root morphology and regulation of the stress-responsive genes. The PGPR is an easy and efficient alternative approach to genetic manipulation and crop enhancement practices because plant breeding and genetic modification are time-consuming and expensive processes for obtaining stress-tolerant varieties. In this review, we will elaborate on PGPR's mechanistic approaches in enhancing the plant stress tolerance to cope with the drought stress.
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Affiliation(s)
- Shahid Ali
- Plant Epigenetic and Development, Northeast Forestry University, Harbin, 150040, China
| | - Naeem Khan
- Department of Agronomy, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, 32611, USA.
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21
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Bhattacharyya A, Pablo CHD, Mavrodi OV, Weller DM, Thomashow LS, Mavrodi DV. Rhizosphere plant-microbe interactions under water stress. ADVANCES IN APPLIED MICROBIOLOGY 2021; 115:65-113. [PMID: 34140134 DOI: 10.1016/bs.aambs.2021.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Climate change, with its extreme temperature, weather and precipitation patterns, is a major global concern of dryland farmers, who currently meet the challenges of climate change agronomically and with growth of drought-tolerant crops. Plants themselves compensate for water stress by modifying aerial surfaces to control transpiration and altering root hydraulic conductance to increase water uptake. These responses are complemented by metabolic changes involving phytohormone network-mediated activation of stress response pathways, resulting in decreased photosynthetic activity and the accumulation of metabolites to maintain osmotic and redox homeostasis. Phylogenetically diverse microbial communities sustained by plants contribute to host drought tolerance by modulating phytohormone levels in the rhizosphere and producing water-sequestering biofilms. Drylands of the Inland Pacific Northwest, USA, illustrate the interdependence of dryland crops and their associated microbiota. Indigenous Pseudomonas spp. selected there by long-term wheat monoculture suppress root diseases via the production of antibiotics, with soil moisture a critical determinant of the bacterial distribution, dynamics and activity. Those pseudomonads producing phenazine antibiotics on wheat had more abundant rhizosphere biofilms and provided improved tolerance to drought, suggesting a role of the antibiotic in alleviation of drought stress. The transcriptome and metabolome studies suggest the importance of wheat root exudate-derived osmoprotectants for the adaptation of these pseudomonads to the rhizosphere lifestyle and support the idea that the exchange of metabolites between plant roots and microorganisms profoundly affects and shapes the belowground plant microbiome under water stress.
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Affiliation(s)
- Ankita Bhattacharyya
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Clint H D Pablo
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Olga V Mavrodi
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - David M Weller
- USDA Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA, United States
| | - Linda S Thomashow
- USDA Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA, United States
| | - Dmitri V Mavrodi
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States.
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22
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Mavrodi OV, McWilliams JR, Peter JO, Berim A, Hassan KA, Elbourne LDH, LeTourneau MK, Gang DR, Paulsen IT, Weller DM, Thomashow LS, Flynt AS, Mavrodi DV. Root Exudates Alter the Expression of Diverse Metabolic, Transport, Regulatory, and Stress Response Genes in Rhizosphere Pseudomonas. Front Microbiol 2021; 12:651282. [PMID: 33936009 PMCID: PMC8079746 DOI: 10.3389/fmicb.2021.651282] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 03/08/2021] [Indexed: 12/20/2022] Open
Abstract
Plants live in association with microorganisms that positively influence plant development, vigor, and fitness in response to pathogens and abiotic stressors. The bulk of the plant microbiome is concentrated belowground at the plant root-soil interface. Plant roots secrete carbon-rich rhizodeposits containing primary and secondary low molecular weight metabolites, lysates, and mucilages. These exudates provide nutrients for soil microorganisms and modulate their affinity to host plants, but molecular details of this process are largely unresolved. We addressed this gap by focusing on the molecular dialog between eight well-characterized beneficial strains of the Pseudomonas fluorescens group and Brachypodium distachyon, a model for economically important food, feed, forage, and biomass crops of the grass family. We collected and analyzed root exudates of B. distachyon and demonstrated the presence of multiple carbohydrates, amino acids, organic acids, and phenolic compounds. The subsequent screening of bacteria by Biolog Phenotype MicroArrays revealed that many of these metabolites provide carbon and energy for the Pseudomonas strains. RNA-seq profiling of bacterial cultures amended with root exudates revealed changes in the expression of genes encoding numerous catabolic and anabolic enzymes, transporters, transcriptional regulators, stress response, and conserved hypothetical proteins. Almost half of the differentially expressed genes mapped to the variable part of the strains’ pangenome, reflecting the importance of the variable gene content in the adaptation of P. fluorescens to the rhizosphere lifestyle. Our results collectively reveal the diversity of cellular pathways and physiological responses underlying the establishment of mutualistic interactions between these beneficial rhizobacteria and their plant hosts.
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Affiliation(s)
- Olga V Mavrodi
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Janiece R McWilliams
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Jacob O Peter
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Anna Berim
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Karl A Hassan
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW, Australia
| | - Liam D H Elbourne
- Department of Molecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - Melissa K LeTourneau
- USDA Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA, United States
| | - David R Gang
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Ian T Paulsen
- Department of Molecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - David M Weller
- USDA Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA, United States
| | - Linda S Thomashow
- USDA Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA, United States
| | - Alex S Flynt
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Dmitri V Mavrodi
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States
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23
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Ruiz A, Herráez M, Costa-Gutierrez SB, Molina-Henares MA, Martínez MJ, Espinosa-Urgel M, Barriuso J. The architecture of a mixed fungal-bacterial biofilm is modulated by quorum-sensing signals. Environ Microbiol 2021; 23:2433-2447. [PMID: 33615654 DOI: 10.1111/1462-2920.15444] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/16/2021] [Accepted: 02/20/2021] [Indexed: 11/26/2022]
Abstract
Interkingdom communication is of particular relevance in polymicrobial biofilms. In this work, the ability of the fungus Ophiostoma piceae to form biofilms individually and in consortium with the bacterium Pseudomonas putida, as well as the effect of fungal and bacterial signal molecules on the architecture of the biofilms was evaluated. Pseudomonas putida KT2440 is able to form biofilms through the secretion of exopolysaccharides and two large extracellular adhesion proteins, LapA and LapF. It has two intercellular signalling systems, one mediated by dodecanoic acid and an orphan LuxR receptor that could participate in the response to AHL-type quorum sensing molecules (QSMs). Furthermore, the dimorphic fungus O. piceae uses farnesol as QSM to control its yeast to hyphae morphological transition. Results show for the first time the ability of this fungus to form biofilms alone and in mixed cultures with the bacterium. Biofilms were induced by bacterial and fungal QSMs. The essential role of LapA-LapF proteins in the architecture of biofilms was corroborated, LapA was induced by farnesol and dodecanol, while LapF by 3-oxo-C6-HSL and 3-oxo-C12-HSL. Our results indicate that fungal signals can induce a transient rise in the levels of the secondary messenger c-di-GMP, which control biofilm formation and architecture.
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Affiliation(s)
- Alberto Ruiz
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CIB-CSIC), C/Ramiro de Maeztu 9, Madrid, 28040, Spain
| | - Marta Herráez
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CIB-CSIC), C/Ramiro de Maeztu 9, Madrid, 28040, Spain
| | - Stefanie B Costa-Gutierrez
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (EEZ-CSIC), C/Profesor Albareda 1, Granada, 18008, Spain
| | - María Antonia Molina-Henares
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (EEZ-CSIC), C/Profesor Albareda 1, Granada, 18008, Spain
| | - María Jesús Martínez
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CIB-CSIC), C/Ramiro de Maeztu 9, Madrid, 28040, Spain
| | - Manuel Espinosa-Urgel
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (EEZ-CSIC), C/Profesor Albareda 1, Granada, 18008, Spain
| | - Jorge Barriuso
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CIB-CSIC), C/Ramiro de Maeztu 9, Madrid, 28040, Spain
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24
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Huertas-Rosales Ó, Romero M, Chan KG, Hong KW, Cámara M, Heeb S, Barrientos-Moreno L, Molina-Henares MA, Travieso ML, Ramos-González MI, Espinosa-Urgel M. Genome-Wide Analysis of Targets for Post-Transcriptional Regulation by Rsm Proteins in Pseudomonas putida. Front Mol Biosci 2021; 8:624061. [PMID: 33693029 PMCID: PMC7937890 DOI: 10.3389/fmolb.2021.624061] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 01/21/2021] [Indexed: 12/31/2022] Open
Abstract
Post-transcriptional regulation is an important step in the control of bacterial gene expression in response to environmental and cellular signals. Pseudomonas putida KT2440 harbors three known members of the CsrA/RsmA family of post-transcriptional regulators: RsmA, RsmE and RsmI. We have carried out a global analysis to identify RNA sequences bound in vivo by each of these proteins. Affinity purification and sequencing of RNA molecules associated with Rsm proteins were used to discover direct binding targets, corresponding to 437 unique RNA molecules, 75 of them being common to the three proteins. Relevant targets include genes encoding proteins involved in signal transduction and regulation, metabolism, transport and secretion, stress responses, and the turnover of the intracellular second messenger c-di-GMP. To our knowledge, this is the first combined global analysis in a bacterium harboring three Rsm homologs. It offers a broad overview of the network of processes subjected to this type of regulation and opens the way to define what are the sequence and structure determinants that define common or differential recognition of specific RNA molecules by these proteins.
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Affiliation(s)
- Óscar Huertas-Rosales
- Department of Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain
| | - Manuel Romero
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Kok-Gan Chan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.,International Genome Centre, Jiangsu University, Zhenjiang, China
| | - Kar-Wai Hong
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.,International Genome Centre, Jiangsu University, Zhenjiang, China
| | - Miguel Cámara
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Stephan Heeb
- National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Laura Barrientos-Moreno
- Department of Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain.,National Biofilms Innovation Centre, Biodiscovery Institute and School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | | | - María L Travieso
- Department of Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain
| | | | - Manuel Espinosa-Urgel
- Department of Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain
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25
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Liu H, Li S, Xie X, Shi Q. Pseudomonas putida actively forms biofilms to protect the population under antibiotic stress. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 270:116261. [PMID: 33359874 DOI: 10.1016/j.envpol.2020.116261] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 12/04/2020] [Accepted: 12/08/2020] [Indexed: 06/12/2023]
Abstract
Antibiotics are frequently used for clinical treatment and by the farming industry, and most of these are eventually released into the surrounding environment. The impact of these antibiotic pollutants on environmental microorganisms is a concern. The present study showed that after Pseudomonas putida entered the logarithmic growth phase, tetracycline strongly stimulated its biofilm formation in a dose-dependent manner. This was supported by the increased expression of the key adhesin gene lapA in response to tetracycline treatment. Tetracycline treatment also changed the expression levels of the exopolysaccharide gene clusters alg, bcs and pea and the adhesin gene lapF. However, these genes did not participate in the tetracycline-induced biofilm formation. When a biofilm had been established, the P. putida population became more tolerant to tetracycline. Confocal laser scanning microscopic images showed that the interior of the biofilm provided favorable conditions that protected bacterial cells from tetracycline. Besides, biofilm formation of P. putida was also promoted by several other antibiotics, including oxytetracycline, fluoroquinolones, rifampicin, and imipenem, but not aminoglycosides. Susceptibility tests suggested that biofilm conferred a higher tolerance on P. putida cells to specific antibiotics (e.g., tetracyclines and fluoroquinolones). These antibiotics exerted a stronger inducing effect on biofilm formation. Together, our results indicate that P. putida actively forms robust biofilms in response to antibiotic stress, and the biofilms improve the survival of bacterial population under such stress.
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Affiliation(s)
- Huizhong Liu
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, 510070, China
| | - Sujuan Li
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, 510070, China
| | - Xiaobao Xie
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, 510070, China.
| | - Qingshan Shi
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, 510070, China.
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26
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Zboralski A, Filion M. Genetic factors involved in rhizosphere colonization by phytobeneficial Pseudomonas spp. Comput Struct Biotechnol J 2020; 18:3539-3554. [PMID: 33304453 PMCID: PMC7711191 DOI: 10.1016/j.csbj.2020.11.025] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 11/10/2020] [Accepted: 11/12/2020] [Indexed: 12/13/2022] Open
Abstract
Plant growth-promoting rhizobacteria (PGPR) actively colonize the soil portion under the influence of plant roots, called the rhizosphere. Many plant-beneficial Pseudomonas spp. have been characterized as PGPR. They are ubiquitous rod-shaped motile Gram-negative bacteria displaying a high metabolic versatility. Their capacity to protect plants from pathogens and improve plant growth closely depends on their rhizosphere colonization abilities. Various molecular and cellular mechanisms are involved in this complex process, such as chemotaxis, biofilm formation, secondary metabolites biosynthesis, metabolic versatility, and evasion of plant immunity. The burst in Pseudomonas spp. genome sequencing in recent years has been crucial to better understand how they colonize the rhizosphere. In this review, we discuss the recent advances regarding these mechanisms and the underlying bacterial genetic factors required for successful rhizosphere colonization.
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Affiliation(s)
- Antoine Zboralski
- Department of Biology, Université de Moncton, Moncton, NB E1A 3E9, Canada
| | - Martin Filion
- Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Jean-sur-Richelieu, QC J3B 3E6, Canada
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27
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Blanco-Romero E, Garrido-Sanz D, Rivilla R, Redondo-Nieto M, Martín M. In Silico Characterization and Phylogenetic Distribution of Extracellular Matrix Components in the Model Rhizobacteria Pseudomonas fluorescens F113 and Other Pseudomonads. Microorganisms 2020; 8:E1740. [PMID: 33171989 PMCID: PMC7716237 DOI: 10.3390/microorganisms8111740] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/01/2020] [Accepted: 11/04/2020] [Indexed: 12/23/2022] Open
Abstract
Biofilms are complex structures that are crucial during host-bacteria interaction and colonization. Bacteria within biofilms are surrounded by an extracellular matrix (ECM) typically composed of proteins, polysaccharides, lipids, and DNA. Pseudomonads contain a variety of ECM components, some of which have been extensively characterized. However, neither the ECM composition of plant-associated pseudomonads nor their phylogenetic distribution within the genus has been so thoroughly studied. In this work, we use in silico methods to describe the ECM composition of Pseudomonas fluorescens F113, a plant growth-promoting rhizobacteria and model for rhizosphere colonization. These components include the polysaccharides alginate, poly-N-acetyl-glucosamine (PNAG) and levan; the adhesins LapA, MapA and PsmE; and the functional amyloids in Pseudomonas. Interestingly, we identified novel components: the Pseudomonas acidic polysaccharide (Pap), whose presence is limited within the genus; and a novel type of Flp/Tad pilus, partially different from the one described in P. aeruginosa. Furthermore, we explored the phylogenetic distribution of the most relevant ECM components in nearly 600 complete Pseudomonas genomes. Our analyses show that Pseudomonas populations contain a diverse set of gene/gene clusters potentially involved in the formation of their ECMs, showing certain commensal versus pathogen lifestyle specialization.
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Affiliation(s)
| | | | | | | | - Marta Martín
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, c/Darwin 2, 28049 Madrid, Spain; (E.B.-R.); (D.G.-S.); (R.R.); (M.R.-N.)
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28
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Lami MJ, Adler C, Caram-Di Santo MC, Zenoff AM, de Cristóbal RE, Espinosa-Urgel M, Vincent PA. Pseudomonas stutzeri MJL19, a rhizosphere-colonizing bacterium that promotes plant growth under saline stress. J Appl Microbiol 2020; 129:1321-1336. [PMID: 32367524 DOI: 10.1111/jam.14692] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 04/28/2020] [Accepted: 04/29/2020] [Indexed: 01/21/2023]
Abstract
AIMS The aim of this study was to find and use rhizobacteria able to confer plants advantages to deal with saline conditions. METHODS AND RESULTS We isolated 24 different bacterial species from the rhizosphere of halophyte plants growing in Santiago del Estero, Argentina salt flat. Four strains were selected upon their ability to grow in salinity and their biochemical traits associated with plant growth promotion. Next, we tested the adhesion on soybean seeds surface and root colonization with the four selected isolates. Isolate 19 stood out from the rest and was selected for further experiments. This strain showed positive chemotaxis towards soybean root exudates and a remarkable ability to form biofilm both in vitro conditions and on soybean roots. Interestingly, this trait was enhanced in high saline conditions, indicating the extremely adapted nature of the bacterium to high salinity. In addition, this strain positively impacted on seed germination, plant growth and general plant health status also under saline stress. CONCLUSIONS A bacterium isolate with outstanding ability to promote seed germination and plant growth under saline conditions was found. SIGNIFICANCE AND IMPACT OF THE STUDY The experimental approach allowed us to find a suitable bacterial candidate for a biofertilizer intended to alleviate saline stress on crops. This would allow the use of soil now considered inadequate for agriculture and thus prevent further advancement of agriculture frontiers into areas of environmental value.
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Affiliation(s)
- M J Lami
- Instituto Superior de Investigaciones Biológicas (INSIBIO-CONICET-UNT), Instituto de Química Biológica 'Dr. Bernabé Bloj', Tucumán, Argentina
- Department of Environmental Protection, Estación Experimental Del Zaidín, CSIC, Granada, Spain
| | - C Adler
- Instituto Superior de Investigaciones Biológicas (INSIBIO-CONICET-UNT), Instituto de Química Biológica 'Dr. Bernabé Bloj', Tucumán, Argentina
| | - M C Caram-Di Santo
- Instituto Superior de Investigaciones Biológicas (INSIBIO-CONICET-UNT), Instituto de Química Biológica 'Dr. Bernabé Bloj', Tucumán, Argentina
| | - A M Zenoff
- Instituto Superior de Investigaciones Biológicas (INSIBIO-CONICET-UNT), Instituto de Química Biológica 'Dr. Bernabé Bloj', Tucumán, Argentina
| | - R E de Cristóbal
- Instituto Superior de Investigaciones Biológicas (INSIBIO-CONICET-UNT), Instituto de Química Biológica 'Dr. Bernabé Bloj', Tucumán, Argentina
| | - M Espinosa-Urgel
- Department of Environmental Protection, Estación Experimental Del Zaidín, CSIC, Granada, Spain
| | - P A Vincent
- Instituto Superior de Investigaciones Biológicas (INSIBIO-CONICET-UNT), Instituto de Química Biológica 'Dr. Bernabé Bloj', Tucumán, Argentina
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29
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Blesken CC, Bator I, Eberlein C, Heipieper HJ, Tiso T, Blank LM. Genetic Cell-Surface Modification for Optimized Foam Fractionation. Front Bioeng Biotechnol 2020; 8:572892. [PMID: 33195133 PMCID: PMC7658403 DOI: 10.3389/fbioe.2020.572892] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 08/31/2020] [Indexed: 12/12/2022] Open
Abstract
Rhamnolipids are among the glycolipids that have been investigated intensively in the last decades, mostly produced by the facultative pathogen Pseudomonas aeruginosa using plant oils as carbon source and antifoam agent. Simplification of downstream processing is envisaged using hydrophilic carbon sources, such as glucose, employing recombinant non-pathogenic Pseudomonas putida KT2440 for rhamnolipid or 3-(3-hydroxyalkanoyloxy)alkanoic acid (HAA, i.e., rhamnolipid precursors) production. However, during scale-up of the cultivation from shake flask to bioreactor, excessive foam formation hinders the use of standard fermentation protocols. In this study, the foam was guided from the reactor to a foam fractionation column to separate biosurfactants from medium and bacterial cells. Applying this integrated unit operation, the space-time yield (STY) for rhamnolipid synthesis could be increased by a factor of 2.8 (STY = 0.17 gRL/L·h) compared to the production in shake flasks. The accumulation of bacteria at the gas-liquid interface of the foam resulted in removal of whole-cell biocatalyst from the reactor with the strong consequence of reduced rhamnolipid production. To diminish the accumulation of bacteria at the gas-liquid interface, we deleted genes encoding cell-surface structures, focusing on hydrophobic proteins present on P. putida KT2440. Strains lacking, e.g., the flagellum, fimbriae, exopolysaccharides, and specific surface proteins, were tested for cell surface hydrophobicity and foam adsorption. Without flagellum or the large adhesion protein F (LapF), foam enrichment of these modified P. putida KT2440 was reduced by 23 and 51%, respectively. In a bioreactor cultivation of the non-motile strain with integrated rhamnolipid production genes, biomass enrichment in the foam was reduced by 46% compared to the reference strain. The intensification of rhamnolipid production from hydrophilic carbon sources presented here is an example for integrated strain and process engineering. This approach will become routine in the development of whole-cell catalysts for the envisaged bioeconomy. The results are discussed in the context of the importance of interacting strain and process engineering early in the development of bioprocesses.
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Affiliation(s)
- Christian C. Blesken
- iAMB - Institute of Applied Microbiology, ABBt - Aachen Biology and Biotechnology, RWTH, Aachen University, Aachen, Germany
| | - Isabel Bator
- iAMB - Institute of Applied Microbiology, ABBt - Aachen Biology and Biotechnology, RWTH, Aachen University, Aachen, Germany
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Christian Eberlein
- Department of Environmental Biotechnology, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Hermann J. Heipieper
- Department of Environmental Biotechnology, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Till Tiso
- iAMB - Institute of Applied Microbiology, ABBt - Aachen Biology and Biotechnology, RWTH, Aachen University, Aachen, Germany
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Lars M. Blank
- iAMB - Institute of Applied Microbiology, ABBt - Aachen Biology and Biotechnology, RWTH, Aachen University, Aachen, Germany
- Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, Jülich, Germany
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Martínez-García E, Fraile S, Rodríguez Espeso D, Vecchietti D, Bertoni G, de Lorenzo V. Naked Bacterium: Emerging Properties of a Surfome-Streamlined Pseudomonas putida Strain. ACS Synth Biol 2020; 9:2477-2492. [PMID: 32786355 DOI: 10.1021/acssynbio.0c00272] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Environmental bacteria are most often endowed with native surface-attachment programs that frequently conflict with efforts to engineer biofilms and synthetic communities with given tridimensional architectures. In this work, we report the editing of the genome of Pseudomonas putida KT2440 for stripping the cells of most outer-facing structures of the bacterial envelope that mediate motion, binding to surfaces, and biofilm formation. To this end, 23 segments of the P. putida chromosome encoding a suite of such functions were deleted, resulting in the surface-naked strain EM371, the physical properties of which changed dramatically in respect to the wild type counterpart. As a consequence, surface-edited P. putida cells were unable to form biofilms on solid supports and, because of the swimming deficiency and other alterations, showed a much faster sedimentation in liquid media. Surface-naked bacteria were then used as carriers of interacting partners (e.g., Jun-Fos domains) ectopically expressed by means of an autotransporter display system on the now easily accessible cell envelope. Abstraction of individual bacteria as adhesin-coated spherocylinders enabled rigorous quantitative description of the multicell interplay brought about by thereby engineered physical interactions. The model was then applied to parametrize the data extracted from automated analysis of confocal microscopy images of the experimentally assembled bacterial flocks for analyzing their structure and distribution. The resulting data not only corroborated the value of P. putida EM371 over the parental strain as a platform for display artificial adhesins but also provided a strategy for rational engineering of catalytic communities.
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Affiliation(s)
- Esteban Martínez-García
- Systems Biology Program, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, 28049 Madrid, Spain
| | - Sofía Fraile
- Systems Biology Program, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, 28049 Madrid, Spain
| | - David Rodríguez Espeso
- Systems Biology Program, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, 28049 Madrid, Spain
| | - Davide Vecchietti
- Department of Biosciences, Università degli Studi di Milano, 20133 Milan, Italy
| | - Giovanni Bertoni
- Department of Biosciences, Università degli Studi di Milano, 20133 Milan, Italy
| | - Víctor de Lorenzo
- Systems Biology Program, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, 28049 Madrid, Spain
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31
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Vance TDR, Ye Q, Conroy B, Davies PL. Essential role of calcium in extending RTX adhesins to their target. JOURNAL OF STRUCTURAL BIOLOGY-X 2020; 4:100036. [PMID: 32984811 PMCID: PMC7493085 DOI: 10.1016/j.yjsbx.2020.100036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/12/2020] [Accepted: 09/02/2020] [Indexed: 11/25/2022]
Abstract
Elongated beta-sandwich repeats are a major part of bacterial RTX adhesins. The repeats are arranged in tandem to extend away from the bacterial surface. Calcium ions are coordinated in the linkers between repeats to stiffen the protein. Rigidification of the tandem repeats further helps extension of the adhesin. The repeats differ greatly between species, but all have Ca2+ in their linkers.
RTX adhesins are long, multi-domain proteins present on the outer membrane of many Gram-negative bacteria. From this vantage point, adhesins use their distal ligand-binding domains for surface attachment leading to biofilm formation. To expand the reach of the ligand-binding domains, RTX adhesins maintain a central extender region of multiple tandem repeats, which makes up most of the proteins’ large molecular weight. Alignments of the 10-15-kDa extender domains show low sequence identity between adhesins. Here we have produced and structurally characterized protein constructs of four tandem repeats (tetra-tandemers) from two different RTX adhesins. In comparing the tetra-tandemers to each other and already solved structures from Marinomonas primoryensis and Salmonella enterica, the extender domains fold as diverse beta-sandwich structures with widely differing calcium contents. However, all the tetra-tandemers have at least one calcium ion coordinated in the linker region between beta-sandwich domains whose role appears to be the rigidification of the extender region to help the adhesin extend its reach.
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Affiliation(s)
- Tyler D R Vance
- Department of Biomedical and Molecular Science, Queen's University Kingston ON, Canada
| | - Qilu Ye
- Department of Biomedical and Molecular Science, Queen's University Kingston ON, Canada
| | - Brigid Conroy
- Department of Biomedical and Molecular Science, Queen's University Kingston ON, Canada
| | - Peter L Davies
- Department of Biomedical and Molecular Science, Queen's University Kingston ON, Canada
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32
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MapA, a Second Large RTX Adhesin Conserved across the Pseudomonads, Contributes to Biofilm Formation by Pseudomonas fluorescens. J Bacteriol 2020; 202:JB.00277-20. [PMID: 32631946 DOI: 10.1128/jb.00277-20] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 06/29/2020] [Indexed: 01/21/2023] Open
Abstract
Mechanisms by which cells attach to a surface and form a biofilm are diverse and differ greatly among organisms. The Gram-negative gammaproteobacterium Pseudomonas fluorescens attaches to a surface through the localization of the large type 1-secreted RTX adhesin LapA to the outer surface of the cell. LapA localization to the cell surface is controlled by the activities of a periplasmic protease, LapG, and an inner membrane-spanning cyclic di-GMP-responsive effector protein, LapD. A previous study identified a second, LapA-like protein encoded in the P. fluorescens Pf0-1 genome: Pfl01_1463. Here, we identified specific growth conditions under which Pfl01_1463, here called MapA (medium adhesion protein A) is a functional adhesin contributing to biofilm formation. This adhesin, like LapA, appears to be secreted through a Lap-related type 1 secretion machinery, and its localization is controlled by LapD and LapG. However, differing roles of LapA and MapA in biofilm formation are achieved, at least in part, through the differences in the sequences of the two adhesins and different distributions of the expression of the lapA and mapA genes within a biofilm. LapA-like proteins are broadly distributed throughout the Proteobacteria, and furthermore, LapA and MapA are well conserved among other Pseudomonas species. Together, our data indicate that the mechanisms by which a cell forms a biofilm and the components of a biofilm matrix can differ depending on growth conditions and the matrix protein(s) expressed.IMPORTANCE Adhesins are critical for the formation and maturation of bacterial biofilms. We identify a second adhesin in P. fluorescens, called MapA, which appears to play a role in biofilm maturation and whose regulation is distinct from the previously reported LapA adhesin, which is critical for biofilm initiation. Analysis of bacterial adhesins shows that LapA-like and MapA-like adhesins are found broadly in pseudomonads and related organisms, indicating that the utilization of different suites of adhesins may be broadly important in the Gammaproteobacteria.
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Arginine as an environmental and metabolic cue for cyclic diguanylate signalling and biofilm formation in Pseudomonas putida. Sci Rep 2020; 10:13623. [PMID: 32788689 PMCID: PMC7423604 DOI: 10.1038/s41598-020-70675-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 08/03/2020] [Indexed: 12/21/2022] Open
Abstract
Cyclic diguanylate (c-di-GMP) is a broadly conserved intracellular second messenger that influences different bacterial processes, including virulence, stress tolerance or social behaviours and biofilm development. Although in most cases the environmental cue that initiates the signal transduction cascade leading to changes in cellular c-di-GMP levels remains unknown, certain l- and d-amino acids have been described to modulate c-di-GMP turnover in some bacteria. In this work, we have analysed the influence of l-amino acids on c-di-GMP levels in the plant-beneficial bacterium Pseudomonas putida KT2440, identifying l-arginine as the main one causing a significant increase in c-di-GMP. Both exogenous (environmental) and endogenous (biosynthetic) l-arginine influence biofilm formation by P. putida through changes in c-di-GMP content and altered expression of structural elements of the biofilm extracellular matrix. The contribution of periplasmic binding proteins forming part of amino acid transport systems to the response to environmental l-arginine was also studied. Contrary to what has been described in other bacteria, in P. putida these proteins seem not to be directly responsible for signal transduction. Rather, their contribution to global l-arginine pools appears to determine changes in c-di-GMP turnover. We propose that arginine plays a connecting role between cellular metabolism and c-di-GMP signalling in P. putida.
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34
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Christensen DG, Marsden AE, Hodge-Hanson K, Essock-Burns T, Visick KL. LapG mediates biofilm dispersal in Vibrio fischeri by controlling maintenance of the VCBS-containing adhesin LapV. Mol Microbiol 2020; 114:742-761. [PMID: 32654271 DOI: 10.1111/mmi.14573] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 07/06/2020] [Accepted: 07/08/2020] [Indexed: 12/18/2022]
Abstract
Efficient symbiotic colonization of the squid Euprymna scolopes by the bacterium Vibrio fischeri depends on bacterial biofilm formation on the surface of the squid's light organ. Subsequently, the bacteria disperse from the biofilm via an unknown mechanism and enter through pores to reach the interior colonization sites. Here, we identify a homolog of Pseudomonas fluorescens LapG as a dispersal factor that promotes cleavage of a biofilm-promoting adhesin, LapV. Overproduction of LapG inhibited biofilm formation and, unlike the wild-type parent, a ΔlapG mutant formed biofilms in vitro. Although V. fischeri encodes two putative large adhesins, LapI (near lapG on chromosome II) and LapV (on chromosome I), only the latter contributed to biofilm formation. Consistent with the Pseudomonas Lap system model, our data support a role for the predicted c-di-GMP-binding protein LapD in inhibiting LapG-dependent dispersal. Furthermore, we identified a phosphodiesterase, PdeV, whose loss promotes biofilm formation similar to that of the ΔlapG mutant and dependent on both LapD and LapV. Finally, we found a minor defect for a ΔlapD mutant in initiating squid colonization, indicating a role for the Lap system in a relevant environmental niche. Together, these data reveal new factors and provide important insights into biofilm dispersal by V. fischeri.
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Affiliation(s)
- David G Christensen
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, USA
| | - Anne E Marsden
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, USA
| | - Kelsey Hodge-Hanson
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, USA
| | - Tara Essock-Burns
- Kewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - Karen L Visick
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, USA
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35
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Collins AJ, Smith TJ, Sondermann H, O'Toole GA. From Input to Output: The Lap/c-di-GMP Biofilm Regulatory Circuit. Annu Rev Microbiol 2020; 74:607-631. [PMID: 32689917 DOI: 10.1146/annurev-micro-011520-094214] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Biofilms are the dominant bacterial lifestyle. The regulation of the formation and dispersal of bacterial biofilms has been the subject of study in many organisms. Over the last two decades, the mechanisms of Pseudomonas fluorescens biofilm formation and regulation have emerged as among the best understood of any bacterial biofilm system. Biofilm formation by P. fluorescens occurs through the localization of an adhesin, LapA, to the outer membrane via a variant of the classical type I secretion system. The decision between biofilm formation and dispersal is mediated by LapD, a c-di-GMP receptor, and LapG, a periplasmic protease, which together control whether LapA is retained or released from the cell surface. LapA localization is also controlled by a complex network of c-di-GMP-metabolizing enzymes. This review describes the current understanding of LapA-mediated biofilm formation by P. fluorescens and discusses several emerging models for the regulation and function of this adhesin.
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Affiliation(s)
- Alan J Collins
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.,Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755, USA;
| | - T Jarrod Smith
- Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755, USA; .,Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA
| | | | - George A O'Toole
- Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755, USA;
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36
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Costa-Gutierrez SB, Lami MJ, Santo MCCD, Zenoff AM, Vincent PA, Molina-Henares MA, Espinosa-Urgel M, de Cristóbal RE. Plant growth promotion by Pseudomonas putida KT2440 under saline stress: role of eptA. Appl Microbiol Biotechnol 2020; 104:4577-4592. [PMID: 32221691 DOI: 10.1007/s00253-020-10516-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 02/11/2020] [Accepted: 03/01/2020] [Indexed: 01/22/2023]
Abstract
New strategies to improve crop yield include the incorporation of plant growth-promoting bacteria in agricultural practices. The non-pathogenic bacterium Pseudomonas putida KT2440 is an excellent root colonizer of crops of agronomical importance and has been shown to activate the induced systemic resistance of plants in response to certain foliar pathogens. In this work, we have analyzed additional plant growth promotion features of this strain. We show it can tolerate high NaCl concentrations and determine how salinity influences traits such as the production of indole compounds, siderophore synthesis, and phosphate solubilization. Inoculation with P. putida KT2440 significantly improved seed germination and root and stem length of soybean and corn plants under saline conditions compared to uninoculated plants, whereas the effects were minor under non-saline conditions. Also, random transposon mutagenesis was used for preliminary identification of KT2440 genes involved in bacterial tolerance to saline stress. One of the obtained mutants was analyzed in detail. The disrupted gene encodes a predicted phosphoethanolamine-lipid A transferase (EptA), an enzyme described to be involved in the modification of lipid A during lipopolysaccharide (LPS) biosynthesis. This mutant showed changes in exopolysaccharide (EPS) production, low salinity tolerance, and reduced competitive fitness in the rhizosphere.
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Affiliation(s)
- Stefanie B Costa-Gutierrez
- Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Chacabuco 461, T4000ILI, San Miguel de Tucumán, Tucumán, Argentina
| | - María Jesús Lami
- Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Chacabuco 461, T4000ILI, San Miguel de Tucumán, Tucumán, Argentina
| | - María Carolina Caram-Di Santo
- Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Chacabuco 461, T4000ILI, San Miguel de Tucumán, Tucumán, Argentina
| | - Ana M Zenoff
- Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Chacabuco 461, T4000ILI, San Miguel de Tucumán, Tucumán, Argentina
| | - Paula A Vincent
- Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Chacabuco 461, T4000ILI, San Miguel de Tucumán, Tucumán, Argentina
| | | | - Manuel Espinosa-Urgel
- Department of Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain
| | - Ricardo E de Cristóbal
- Instituto Superior de Investigaciones Biológicas (INSIBIO, CONICET-UNT) and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Chacabuco 461, T4000ILI, San Miguel de Tucumán, Tucumán, Argentina.
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Abstract
Pseudomonas putidais a fast-growing bacterium found mostly in temperate soil and water habitats. The metabolic versatility ofP. putidamakes this organism attractive for biotechnological applications such as biodegradation of environmental pollutants and synthesis of added-value chemicals (biocatalysis). This organism has been extensively studied in respect to various stress responses, mechanisms of genetic plasticity and transcriptional regulation of catabolic genes.P. putidais able to colonize the surface of living organisms, but is generally considered to be of low virulence. A number ofP. putidastrains are able to promote plant growth. The aim of this review is to give historical overview of the discovery of the speciesP. putidaand isolation and characterization ofP. putidastrains displaying potential for biotechnological applications. This review also discusses some major findings inP. putidaresearch encompassing regulation of catabolic operons, stress-tolerance mechanisms and mechanisms affecting evolvability of bacteria under conditions of environmental stress.
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King MM, Kayastha BB, Franklin MJ, Patrauchan MA. Calcium Regulation of Bacterial Virulence. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:827-855. [PMID: 31646536 DOI: 10.1007/978-3-030-12457-1_33] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Calcium (Ca2+) is a universal signaling ion, whose major informational role shaped the evolution of signaling pathways, enabling cellular communications and responsiveness to both the intracellular and extracellular environments. Elaborate Ca2+ regulatory networks have been well characterized in eukaryotic cells, where Ca2+ regulates a number of essential cellular processes, ranging from cell division, transport and motility, to apoptosis and pathogenesis. However, in bacteria, the knowledge on Ca2+ signaling is still fragmentary. This is complicated by the large variability of environments that bacteria inhabit with diverse levels of Ca2+. Yet another complication arises when bacterial pathogens invade a host and become exposed to different levels of Ca2+ that (1) are tightly regulated by the host, (2) control host defenses including immune responses to bacterial infections, and (3) become impaired during diseases. The invading pathogens evolved to recognize and respond to the host Ca2+, triggering the molecular mechanisms of adhesion, biofilm formation, host cellular damage, and host-defense resistance, processes enabling the development of persistent infections. In this review, we discuss: (1) Ca2+ as a determinant of a host environment for invading bacterial pathogens, (2) the role of Ca2+ in regulating main events of host colonization and bacterial virulence, and (3) the molecular mechanisms of Ca2+ signaling in bacterial pathogens.
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Affiliation(s)
- Michelle M King
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA
| | - Biraj B Kayastha
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA
| | - Michael J Franklin
- Department of Microbiology and Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA
| | - Marianna A Patrauchan
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA.
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39
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Molina L, Segura A, Duque E, Ramos JL. The versatility of Pseudomonas putida in the rhizosphere environment. ADVANCES IN APPLIED MICROBIOLOGY 2019; 110:149-180. [PMID: 32386604 DOI: 10.1016/bs.aambs.2019.12.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
This article addresses the lifestyle of Pseudomonas and focuses on how Pseudomonas putida can be used as a model system for biotechnological processes in agriculture, and in the removal of pollutants from soils. In this chapter we aim to show how a deep analysis using genetic information and experimental tests has helped to reveal insights into the lifestyle of Pseudomonads. Pseudomonas putida is a Plant Growth Promoting Rhizobacteria (PGPR) that establishes commensal relationships with plants. The interaction involves a series of functions encoded by core genes which favor nutrient mobilization, prevention of pathogen development and efficient niche colonization. Certain Pseudomonas putida strains harbor accessory genes that confer specific biodegradative properties and because these microorganisms can thrive on the roots of plants they can be exploited to remove pollutants via rhizoremediation, making the consortium plant/Pseudomonas a useful tool to combat pollution.
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Affiliation(s)
- Lázaro Molina
- CSIC- Estación Experimental del Zaidín, Granada, Spain
| | - Ana Segura
- CSIC- Estación Experimental del Zaidín, Granada, Spain
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40
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Wynands B, Otto M, Runge N, Preckel S, Polen T, Blank LM, Wierckx N. Streamlined Pseudomonas taiwanensis VLB120 Chassis Strains with Improved Bioprocess Features. ACS Synth Biol 2019; 8:2036-2050. [PMID: 31465206 DOI: 10.1021/acssynbio.9b00108] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Microbes harbor many traits that are dispensable or even unfavorable under industrial and laboratory settings. The elimination of such traits could improve the host's efficiency, genetic stability, and robustness, thereby increasing the predictability and boosting its performance as a microbial cell factory. We engineered solvent-tolerant Pseudomonas taiwanensis VLB120 to yield streamlined chassis strains with higher growth rates and biomass yields, enhanced solvent tolerance, and improved process performance. In total, the genome was reduced by up to 10%. This was achieved by the elimination of genes that enable the cell to swim and form biofilms and by the deletion of the megaplasmid pSTY and large proviral segments. The resulting strain GRC1 had a 15% higher growth rate and biomass yield than the wildtype. However, this strain lacks the pSTY-encoded efflux pump TtgGHI, rendering it solvent-sensitive. Through reintegration of ttgGHI by chromosomal insertion without (GRC2) and with (GRC3) the corresponding regulator genes, the solvent-tolerant phenotype was enhanced. The generated P. taiwanensis GRC strains enlarge the repertoire of streamlined chassis with enhanced key performance indicators, making them attractive hosts for biotechnological applications. The different solvent tolerance levels of GRC1, GRC2, and GRC3 enable the selection of a fitting host platform in relation to the desired process requirements in a chassis à la carte principle. This was demonstrated in a metabolic engineering approach for the production of phenol from glycerol. The streamlined producer GRC1Δ5-TPL38 outperformed the equivalent nonstreamlined producer VLB120Δ5-TPL38 concerning phenol titer, rate, and yield, thereby highlighting the added value of the streamlined chassis.
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Affiliation(s)
- Benedikt Wynands
- Institute of Applied Microbiology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Maike Otto
- Institute of Applied Microbiology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Nadine Runge
- Institute of Applied Microbiology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Sarah Preckel
- Institute of Applied Microbiology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Tino Polen
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Lars M. Blank
- Institute of Applied Microbiology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Nick Wierckx
- Institute of Applied Microbiology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
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41
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Guo S, Vance TD, Stevens CA, Voets I, Davies PL. RTX Adhesins are Key Bacterial Surface Megaproteins in the Formation of Biofilms. Trends Microbiol 2019; 27:453-467. [DOI: 10.1016/j.tim.2018.12.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 11/13/2018] [Accepted: 12/12/2018] [Indexed: 12/20/2022]
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42
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Defining the Genetic Basis of Plant⁻Endophytic Bacteria Interactions. Int J Mol Sci 2019; 20:ijms20081947. [PMID: 31010043 PMCID: PMC6515357 DOI: 10.3390/ijms20081947] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 04/17/2019] [Accepted: 04/18/2019] [Indexed: 01/17/2023] Open
Abstract
Endophytic bacteria, which interact closely with their host, are an essential part of the plant microbiome. These interactions enhance plant tolerance to environmental changes as well as promote plant growth, thus they have become attractive targets for increasing crop production. Numerous studies have aimed to characterise how endophytic bacteria infect and colonise their hosts as well as conferring important traits to the plant. In this review, we summarise the current knowledge regarding endophytic colonisation and focus on the insights that have been obtained from the mutants of bacteria and plants as well as ‘omic analyses. These show how endophytic bacteria produce various molecules and have a range of activities related to chemotaxis, motility, adhesion, bacterial cell wall properties, secretion, regulating transcription and utilising a substrate in order to establish a successful interaction. Colonisation is mediated by plant receptors and is regulated by the signalling that is connected with phytohormones such as auxin and jasmonic (JA) and salicylic acids (SA). We also highlight changes in the expression of small RNAs and modifications of the cell wall properties. Moreover, in order to exploit the beneficial plant-endophytic bacteria interactions in agriculture successfully, we show that the key aspects that govern successful interactions remain to be defined.
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43
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Wheatley RM, Poole PS. Mechanisms of bacterial attachment to roots. FEMS Microbiol Rev 2018; 42:448-461. [PMID: 29672765 DOI: 10.1093/femsre/fuy014] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 04/14/2018] [Indexed: 11/13/2022] Open
Abstract
The attachment of bacteria to roots constitutes the first physical step in many plant-microbe interactions. These interactions exert both positive and negative influences on agricultural systems depending on whether a growth-promoting, symbiotic or pathogenic relationship transpires. A common biphasic mechanism of root attachment exists across agriculturally important microbial species, including Rhizobium, Agrobacterium, Pseudomonas, Azospirillum and Salmonella. Attachment studies have revealed how plant-microbe interactions develop, and how to manipulate these relationships for agricultural benefit. Here, we review our current understanding of the molecular mechanisms governing plant-microbe root attachment and draw together a common biphasic model.
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Affiliation(s)
- Rachel M Wheatley
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Philip S Poole
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
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44
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Liu H, Yan H, Xiao Y, Nie H, Huang Q, Chen W. The exopolysaccharide gene cluster pea is transcriptionally controlled by RpoS and repressed by AmrZ in Pseudomonas putida KT2440. Microbiol Res 2018; 218:1-11. [PMID: 30454651 DOI: 10.1016/j.micres.2018.09.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 08/29/2018] [Accepted: 09/05/2018] [Indexed: 10/28/2022]
Abstract
In Pseudomonas putida KT2440, the exopolysaccharide Pea is associated with biofilm stability and pellicle formation; however, little is known about its regulatory pathway. In this study, we identified that the gene cluster pea was transcribed from 25 bp upstream of the operon and the stationary phase alternative sigma factor RpoS regulated the transcription of pea. When RpoS was absent, another sigma factor, likely the housekeeping sigma factor RpoD, could also mediate pea transcription but at a low level. The function of Pea polysaccharide was further confirmed to be necessary for full production of biofilm, formation of pellicle and c-di-GMP-dependent wrinkly colony morphology. Additionally, evidences were provided to demonstrate that the transcriptional regulator AmrZ was a negative regulator for pea expression. DNase I footprinting studies verified that AmrZ bound directly to the site overlapping the pea promoter, which might interfere with the binding of RNA polymerase to the promoter and resulted in inhibition of transcription initiation.
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Affiliation(s)
- Huizhong Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Huaduo Yan
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Yujie Xiao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Hailing Nie
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
| | - Wenli Chen
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
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45
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Volke DC, Nikel PI. Getting Bacteria in Shape: Synthetic Morphology Approaches for the Design of Efficient Microbial Cell Factories. ACTA ACUST UNITED AC 2018. [DOI: 10.1002/adbi.201800111] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Daniel C. Volke
- The Novo Nordisk Foundation Center for Biosustainability; Technical University of Denmark; Kemitorvet 2800 Kgs. Lyngby Denmark
| | - Pablo I. Nikel
- The Novo Nordisk Foundation Center for Biosustainability; Technical University of Denmark; Kemitorvet 2800 Kgs. Lyngby Denmark
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46
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Guo S, Langelaan DN, Phippen SW, Smith SP, Voets IK, Davies PL. Conserved structural features anchor biofilm-associated RTX-adhesins to the outer membrane of bacteria. FEBS J 2018; 285:1812-1826. [PMID: 29575515 DOI: 10.1111/febs.14441] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 02/05/2018] [Accepted: 03/19/2018] [Indexed: 11/30/2022]
Abstract
Repeats-in-toxin (RTX) adhesins are present in many Gram-negative bacteria to facilitate biofilm formation. Previously, we reported that the 1.5-MDa RTX adhesin (MpIBP) from the Antarctic bacterium, Marinomonas primoryensis, is tethered to the bacterial cell surface via its N-terminal Region I (RI). Here, we show the detailed structural features of RI. It has an N-terminal periplasmic retention domain (RIN), a central domain (RIM) that can insert into the β-barrel of an outer-membrane pore protein during MpIBP secretion, and three extracellular domains at its C terminus (RIC) that transition the protein into the extender region (RII). RIN has a novel β-sandwich fold with a similar shape to βγ-crystallins and tryptophan RNA attenuation proteins. Because RIM undergoes fast and extensive degradation in vitro, its narrow cylindrical shape was rapidly measured by small-angle X-ray scattering before proteolysis could occur. The crystal structure of RIC comprises three tandem β-sandwich domains similar to those in RII, but increasing in their hydrophobicity with proximity to the outer membrane. In addition, the key Ca2+ ion that rigidifies the linkers between RII domains is not present between the first two of these RIC domains. This more flexible RI linker near the cell surface can act as a 'pivot' to help the 0.6-μm-long MpIBP sweep over larger volumes to find its binding partners. Since the physical features of RI are well conserved in the RTX adhesins of many Gram-negative bacteria, our detailed structural and bioinformatic analyses serve as a model for investigating the surface retention of biofilm-forming bacteria, including human pathogens.
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Affiliation(s)
- Shuaiqi Guo
- Protein Function Discovery Group, Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Canada.,Institute for Complex Molecular Systems, Laboratory of Macromolecular and Organic Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, the Netherlands.,Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, the Netherlands
| | - David N Langelaan
- Protein Function Discovery Group, Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Canada
| | - Sean W Phippen
- Protein Function Discovery Group, Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Canada
| | - Steven P Smith
- Protein Function Discovery Group, Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Canada
| | - Ilja K Voets
- Institute for Complex Molecular Systems, Laboratory of Macromolecular and Organic Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, the Netherlands.,Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, the Netherlands
| | - Peter L Davies
- Protein Function Discovery Group, Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Canada
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47
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Lee Y, Song S, Sheng L, Zhu L, Kim JS, Wood TK. Substrate Binding Protein DppA1 of ABC Transporter DppBCDF Increases Biofilm Formation in Pseudomonas aeruginosa by Inhibiting Pf5 Prophage Lysis. Front Microbiol 2018; 9:30. [PMID: 29416528 PMCID: PMC5787571 DOI: 10.3389/fmicb.2018.00030] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 01/08/2018] [Indexed: 11/13/2022] Open
Abstract
Filamentous phage impact biofilm development, stress tolerance, virulence, biofilm dispersal, and colony variants. Previously, we identified 137 Pseudomonas aeruginosa PA14 mutants with more than threefold enhanced and 88 mutants with more than 10-fold reduced biofilm formation by screening 5850 transposon mutants (PLoS Pathogens5: e1000483, 2009). Here, we characterized the function of one of these 225 mutations, dppA1 (PA14_58350), in regard to biofilm formation. DppA1 is a substrate-binding protein (SBP) involved in peptide utilization via the DppBCDF ABC transporter system. We show that compared to the wild-type strain, inactivating dppA1 led to 68-fold less biofilm formation in a static model and abolished biofilm formation in flow cells. Moreover, the dppA1 mutant had a delay in swarming and produced 20-fold less small-colony variants, and both biofilm formation and swarming were complemented by producing DppA1. A whole-transcriptome analysis showed that only 10 bacteriophage Pf5 genes were significantly induced in the biofilm cells of the dppA1 mutant compared to the wild-type strain, and inactivation of dppA1 resulted in a 600-fold increase in Pf5 excision and a million-fold increase in phage production. As expected, inactivating Pf5 genes PA0720 and PA0723 increased biofilm formation substantially. Inactivation of DppA1 also reduced growth (due to cell lysis). Hence, DppA1 increases biofilm formation by repressing Pf5 prophage.
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Affiliation(s)
- Yunho Lee
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, United States
| | - Sooyeon Song
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, United States
| | - Lili Sheng
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, United States
| | - Lei Zhu
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, United States
| | | | - Thomas K. Wood
- Department of Chemical Engineering, Pennsylvania State University, University Park, PA, United States
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, United States
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48
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Yoshida K, Toyofuku M, Obana N, Nomura N. Biofilm formation by Paracoccus denitrificans requires a type I secretion system-dependent adhesin BapA. FEMS Microbiol Lett 2017; 364:2966325. [PMID: 28158695 DOI: 10.1093/femsle/fnx029] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 01/29/2017] [Indexed: 12/12/2022] Open
Abstract
Paracoccus denitrificans is a non-swimming Gram-negative bacterium, with versatile respiration capability which has remarkable potentials for bioremediation, especially in water treatment. Although biofilms are important in water treatment systems, the genetic mechanisms underlying the cellular adherence and biofilm formation of this bacterium remain unknown. We show that P. denitrificans forms a thin biofilm on surfaces at the air-liquid interface under static conditions. The initial step of biofilm formation requires a biofilm-associated protein BapA, which we identified by transposon mutant screening. BapA contains a unique sequence of dipeptide repeats of aspartate and alanine. Our data indicate that BapA is translocated to the extracellular milieu by a type 1 secretion system, where it enables the cells to attach to the substratum. Furthermore, superresolution microscopy shows that BapA is localized on the cell surface, which alters the cell surface hydrophobicity. Our results show a crucial role of BapA that promotes the adhesion and biofilm formation of P. denitrificans.
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Affiliation(s)
- Keitaro Yoshida
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
| | - Masanori Toyofuku
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan.,Department of Plant and Microbial Biology, University of Zurich, Zürich 8008, Switzerland
| | - Nozomu Obana
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
| | - Nobuhiko Nomura
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
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49
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De León KB, Zane GM, Trotter VV, Krantz GP, Arkin AP, Butland GP, Walian PJ, Fields MW, Wall JD. Unintended Laboratory-Driven Evolution Reveals Genetic Requirements for Biofilm Formation by Desulfovibrio vulgaris Hildenborough. mBio 2017; 8:e01696-17. [PMID: 29042504 PMCID: PMC5646257 DOI: 10.1128/mbio.01696-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 09/18/2017] [Indexed: 12/28/2022] Open
Abstract
Biofilms of sulfate-reducing bacteria (SRB) are of particular interest as members of this group are culprits in corrosion of industrial metal and concrete pipelines as well as being key players in subsurface metal cycling. Yet the mechanism of biofilm formation by these bacteria has not been determined. Here we show that two supposedly identical wild-type cultures of the SRB Desulfovibrio vulgaris Hildenborough maintained in different laboratories have diverged in biofilm formation. From genome resequencing and subsequent mutant analyses, we discovered that a single nucleotide change within DVU1017, the ABC transporter of a type I secretion system (T1SS), was sufficient to eliminate biofilm formation in D. vulgaris Hildenborough. Two T1SS cargo proteins were identified as likely biofilm structural proteins, and the presence of at least one (with either being sufficient) was shown to be required for biofilm formation. Antibodies specific to these biofilm structural proteins confirmed that DVU1017, and thus the T1SS, is essential for localization of these adhesion proteins on the cell surface. We propose that DVU1017 is a member of the lapB category of microbial surface proteins because of its phenotypic similarity to the adhesin export system described for biofilm formation in the environmental pseudomonads. These findings have led to the identification of two functions required for biofilm formation in D. vulgaris Hildenborough and focus attention on the importance of monitoring laboratory-driven evolution, as phenotypes as fundamental as biofilm formation can be altered.IMPORTANCE The growth of bacteria attached to a surface (i.e., biofilm), specifically biofilms of sulfate-reducing bacteria, has a profound impact on the economy of developed nations due to steel and concrete corrosion in industrial pipelines and processing facilities. Furthermore, the presence of sulfate-reducing bacteria in oil wells causes oil souring from sulfide production, resulting in product loss, a health hazard to workers, and ultimately abandonment of wells. Identification of the required genes is a critical step for determining the mechanism of biofilm formation by sulfate reducers. Here, the transporter by which putative biofilm structural proteins are exported from sulfate-reducing Desulfovibrio vulgaris Hildenborough cells was discovered, and a single nucleotide change within the gene coding for this transporter was found to be sufficient to completely stop formation of biofilm.
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Affiliation(s)
- Kara B De León
- Department of Biochemistry, University of Missouri, Columbia, Missouri, USA
| | - Grant M Zane
- Department of Biochemistry, University of Missouri, Columbia, Missouri, USA
| | - Valentine V Trotter
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Gregory P Krantz
- Department of Microbiology and Immunology, Montana State University, Bozeman, Montana, USA
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
| | - Adam P Arkin
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Department of Bioengineering, University of California, Berkeley, California, USA
| | - Gareth P Butland
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Peter J Walian
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Matthew W Fields
- Department of Microbiology and Immunology, Montana State University, Bozeman, Montana, USA
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
| | - Judy D Wall
- Department of Biochemistry, University of Missouri, Columbia, Missouri, USA
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Nie H, Xiao Y, Liu H, He J, Chen W, Huang Q. FleN and FleQ play a synergistic role in regulating lapA and bcs operons in Pseudomonas putida KT2440. ENVIRONMENTAL MICROBIOLOGY REPORTS 2017; 9:571-580. [PMID: 28517238 DOI: 10.1111/1758-2229.12547] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 05/02/2017] [Accepted: 05/05/2017] [Indexed: 06/07/2023]
Abstract
FleN generally functions as an antagonist of FleQ in regulating flagellar genes and biofilm matrix related genes in Pseudomonas aeruginosa. Here, we found that in Pseudomonas putida KT2440, FleN and FleQ play a synergistic role in regulating two biofilm matrix coding operons, lapA and bcs. FleN deletion decreased the transcription of lapA and increased the transcription of bcs operon, and the same trend was observed in fleQ deletion mutant before. In vitro experiments showed that FleN promoted the binding of FleQ to the lapA/bcs promoter DNA especially in the presence of ATP. Both phenotype observation and transcription analysis showed that, similar to fleQ deletion, fleN deletion significantly weaken the effect of high c-di-GMP level on biofilm formation, surface winkle phenotype and expression of lapA and bcs operons. Mutagenesis of the putative ATP binding motif in FleNK21Q revealed that FleN ATPase activity played an essential role in the regulation of flagellar number and swimming motility but was not critical for biofilm formation. Our results revealed that FleN was not an antagonist of FleQ but a synergistic factor of FleQ in regulating the two biofilm matrix coding operons in P. putida KT2440.
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Affiliation(s)
- Hailing Nie
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Yujie Xiao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Huizhong Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Jinzhi He
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Wenli Chen
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
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