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Fernández-Juárez V, Hallstrøm S, Pacherres CO, Wang J, Coll-Garcia G, Kühl M, Riemann L. Biofilm formation and cell plasticity drive diazotrophy in an anoxygenic phototrophic bacterium. Appl Environ Microbiol 2023; 89:e0102723. [PMID: 37882569 PMCID: PMC10686084 DOI: 10.1128/aem.01027-23] [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: 06/23/2023] [Accepted: 09/14/2023] [Indexed: 10/27/2023] Open
Abstract
IMPORTANCE The contribution of non-cyanobacterial diazotrophs (NCDs) to total N2 fixation in the marine water column is unknown, but their importance is likely constrained by the limited availability of dissolved organic matter and low O2 conditions. Light could support N2 fixation and growth by NCDs, yet no examples from bacterioplankton exist. In this study, we show that the phototrophic NCD, Rhodopseudomonas sp. BAL398, which is a member of the diazotrophic community in the surface waters of the Baltic Sea, can utilize light. Our study highlights the significance of biofilm formation for utilizing light and fixing N2 under oxic conditions and the role of cell plasticity in regulating these processes. Our findings have implications for the general understanding of the ecology and importance of NCDs in marine waters.
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Affiliation(s)
- Víctor Fernández-Juárez
- Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Søren Hallstrøm
- Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, Denmark
| | - Cesar O. Pacherres
- Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Jiaqi Wang
- Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Guillem Coll-Garcia
- Microbiology, Biology Department, University of the Balearic Islands, Palma de Mallorca, Spain
- Environmental Microbiology Group, Mediterranean Institute for Advanced Studies (CSIC-UIB), Esporles, Spain
| | - Michael Kühl
- Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Lasse Riemann
- Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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2
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Segura Y, Molina R, Rodríguez I, Hülsen T, Batstone D, Monsalvo V, Martínez F, Melero JA, Puyol D. Improvement of biogas production and nitrogen recovery in anaerobic digestion of purple phototrophic bacteria by thermal hydrolysis. BIORESOURCE TECHNOLOGY 2023; 367:128250. [PMID: 36334866 DOI: 10.1016/j.biortech.2022.128250] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/23/2022] [Accepted: 10/28/2022] [Indexed: 06/16/2023]
Abstract
Purple phototrophic bacteria (PPB) are a novel driver to recover organics and nutrients from wastewater by assimilative growth. Depending on the source, assimilated resources from the PPB biomass can still be recovered after a releasing step. Anaerobic digestion (AD) releases carbonand nutrients, but the release is incomplete. Thermal hydrolysis (TH) as a pretreatment before AD improves the digestibility, release, and subsequent recovery potentials. This work determines the effects of TH in batch and continuous modes regarding methane potential, nutrients' release efficiencies, volatile solids destruction, degradability, and hydrolysis rates. Continuous runs over 165 days (d) confirmed enhanced recovery potentials, achieving up to 380 LCH4/kgVS (83 % solids destruction) and 73 % N release, respectively. The TH pretreatment is energy-intensive, but with appropriate heat recovery and increased methane production in the AD of the pretreated biomass, a combined configuration is energy positive.
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Affiliation(s)
- Y Segura
- Department of Chemical and Environmental Technology, Rey Juan Carlos University, ESCET, Madrid 28933, Spain.
| | - R Molina
- Department of Chemical and Environmental Technology, Rey Juan Carlos University, ESCET, Madrid 28933, Spain
| | - I Rodríguez
- Department of Chemical and Environmental Technology, Rey Juan Carlos University, ESCET, Madrid 28933, Spain
| | - T Hülsen
- Advanced Water Management Centre, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - D Batstone
- Advanced Water Management Centre, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - V Monsalvo
- Department of Innovation and Technology, FCC AQUALIA, Madrid 28050, Spain
| | - F Martínez
- Department of Chemical and Environmental Technology, Rey Juan Carlos University, ESCET, Madrid 28933, Spain
| | - J A Melero
- Department of Chemical and Environmental Technology, Rey Juan Carlos University, ESCET, Madrid 28933, Spain
| | - D Puyol
- Department of Chemical and Environmental Technology, Rey Juan Carlos University, ESCET, Madrid 28933, Spain
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3
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Schwartz DA, Lehmkuhl BK, Lennon JT. Phage-Encoded Sigma Factors Alter Bacterial Dormancy. mSphere 2022; 7:e0029722. [PMID: 35856690 PMCID: PMC9429907 DOI: 10.1128/msphere.00297-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 06/24/2022] [Indexed: 11/20/2022] Open
Abstract
By entering a reversible state of reduced metabolic activity, dormant microorganisms are able to tolerate suboptimal conditions that would otherwise reduce their fitness. Dormancy may also benefit bacteria by serving as a refuge from parasitic infections. Here, we focus on dormancy in the Bacillota, where endospore development is transcriptionally regulated by the expression of sigma factors. A disruption of this process could influence the survivorship or reproduction of phages that infect spore-forming hosts with implications for coevolutionary dynamics. We characterized the distribution of sigma factors in over 4,000 genomes of diverse phages capable of infecting hosts that span the bacterial domain. From this, we identified homologs of sporulation-specific sigma factors in phages that infect spore-forming hosts. Unlike sigma factors required for phage reproduction, we provide evidence that sporulation-like sigma factors are nonessential for lytic infection. However, when expressed in the spore-forming Bacillus subtilis, some of these phage-derived sigma factors can activate the bacterial sporulation gene network and lead to a reduction in spore yield. Our findings suggest that the acquisition of host-like transcriptional regulators may allow phages to manipulate a complex and ancient trait in one of the most abundant cell types on Earth. IMPORTANCE As obligate parasites, phages exert strong top-down pressure on host populations with eco-evolutionary implications for community dynamics and ecosystem functioning. The process of phage infection, however, is constrained by bottom-up processes that influence the energetic and nutritional status of susceptible hosts. Many phages have acquired auxiliary genes from bacteria, which can be used to exploit host metabolism with consequences for phage fitness. In this study, we demonstrate that phages infecting spore-forming bacteria carry homologs of sigma factors, which their hosts use to orchestrate gene expression during spore development. By tapping into regulatory gene networks, phages may manipulate the physiology and survival strategies of nongrowing bacteria in ways that influence host-parasite coevolution.
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Affiliation(s)
- D. A. Schwartz
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - B. K. Lehmkuhl
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - J. T. Lennon
- Department of Biology, Indiana University, Bloomington, Indiana, USA
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4
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Ashok N, He K, Bauer CE. No Light, No Germination: Excitation of the Rhodospirillum centenum Photosynthetic Apparatus Is Necessary and Sufficient for Cyst Germination. mBio 2021; 12:e03619-20. [PMID: 33727361 PMCID: PMC8092318 DOI: 10.1128/mbio.03619-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 01/05/2023] Open
Abstract
Rhodospirillum centenum is a Gram-negative alphaproteobacterium that is capable of differentiating into dormant cysts that are metabolically inactive and desiccation resistant. Like spores synthesized by many Gram-positive species, dormant R. centenum cysts germinate in response to an environmental signal, indicating that conditions favor survival and proliferation. Factors that induce germination are called germinants and are often both niche and species specific. In this study, we have identified photosynthesis as a niche-specific germinant for R. centenum cyst germination. Specifically, excitation of wild-type cysts suspended in a nutrient-free buffer with far-red light at >750 nm results in rapid germination. This is in stark contrast to mutant strains deficient in photosynthesis that fail to germinate upon exposure to far-red light under all assayed conditions. We also show that photosynthesis-induced germination occurs in a carbon- and nitrogen-free buffer even in strains that are deficient in carbon or nitrogen fixation. These results demonstrate that photosynthesis not only is necessary for germination but is itself sufficient for the germination of R. centenum cysts.IMPORTANCE Environmental cues that signal Gram-positive spores to germinate (termed germinants) have been identified for several Bacillus and Clostridium species. These studies showed that germinants are niche and species specific. For example, Clostridium difficile spores sense bile salts as a germinant as their presence informs these cells of an intestinal environment. Bacillus fastidiosus spores use uric acid as a germinant that is present in soil and poultry litter as this species inhabits poultry litter. It is evident from these studies that dormant cells sample their environment to assess whether conditions are advantageous for the propagation and survival of vegetative cells. To date, a limited number of germinants have been defined for only a few Gram-positive spore-forming species. Beyond that group, there is scant information on what cues signal dormant cells to exit dormancy. In our study, we show that the versatile Gram-negative photosynthetic bacterium Rhodospirillum centenum uses light-driven photosynthesis, and not the availability of nutrients, to trigger the germination of dormant cysts. This use of light-driven photosynthesis as a germinant is surprising as this species is also capable of growing under dark conditions using exogenous carbon sources for energy. Consequently, photosynthetic growth appears to be the preferred growth mechanism by this species.
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Affiliation(s)
- Nandhini Ashok
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Kuang He
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, USA
| | - Carl E Bauer
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, USA
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5
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Hülsen T, Lu Y, Rodríguez I, Segura Y, Martínez F, Puyol D, Batstone DJ. Anaerobic digestion of purple phototrophic bacteria - The release step of the partition-release-recover concept. BIORESOURCE TECHNOLOGY 2020; 306:123125. [PMID: 32197190 DOI: 10.1016/j.biortech.2020.123125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 03/01/2020] [Accepted: 03/01/2020] [Indexed: 06/10/2023]
Abstract
Purple phototrophic bacteria (PPB) have been proposed as a high-growth, assimilative option for wastewater treatment. The original partition-release-recover concept proposal requires their near complete digestion and release (and subsequent recovery) of energy and nutrients in an anaerobic digester. While the growth (partition) step has been extensively assessed, no work has been done on their anaerobic digestion characteristics (release). Continuous mesophilic (20d) and thermophilic (10d) digestion could achieve around 55% volatile solids degradation (VSD), with 35% (mesophilic) and 20% (thermophilic) nitrogen solubilisation. Post digestion (with/without pretreatment) could increase the VSD to 70% and nitrogen solubilisation to 43%. A number of pretreatment options were tested, with high temperature and sonication being relatively effective, and chemical treatment, and temperature phased digestion being relatively ineffective vs controls. Overall, anaerobic digestion of PPB results in substantial residual particulate material, with an increased nitrogen content, and avenues to effectively utilise this residue should be identified.
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Affiliation(s)
- Tim Hülsen
- Advanced Water Management Centre, Gehrmann Building, The University of Queensland, Brisbane, Queensland 4072, Australia; CRC for Water Sensitive Cities, PO Box 8000, Clayton, Victoria 3800, Australia.
| | - Yang Lu
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore
| | - Iván Rodríguez
- Group of Chemical and Environmental Engineering (GIQA), University Rey Juan Carlos, C/Tulipán, s/n, 28933 Móstoles, Madrid, Spain
| | - Yolanda Segura
- Group of Chemical and Environmental Engineering (GIQA), University Rey Juan Carlos, C/Tulipán, s/n, 28933 Móstoles, Madrid, Spain
| | - Fernando Martínez
- Group of Chemical and Environmental Engineering (GIQA), University Rey Juan Carlos, C/Tulipán, s/n, 28933 Móstoles, Madrid, Spain
| | - Daniel Puyol
- Group of Chemical and Environmental Engineering (GIQA), University Rey Juan Carlos, C/Tulipán, s/n, 28933 Móstoles, Madrid, Spain
| | - Damien J Batstone
- Advanced Water Management Centre, Gehrmann Building, The University of Queensland, Brisbane, Queensland 4072, Australia; CRC for Water Sensitive Cities, PO Box 8000, Clayton, Victoria 3800, Australia
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6
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Ashok N, Bauer CE. Evidence of defined temporal expression patterns that lead a gram-negative cell out of dormancy. PLoS Genet 2020; 16:e1008660. [PMID: 32203501 PMCID: PMC7117780 DOI: 10.1371/journal.pgen.1008660] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 04/02/2020] [Accepted: 02/07/2020] [Indexed: 01/02/2023] Open
Abstract
Many bacterial species are capable of forming long-lived dormant cells. The best characterized are heat and desiccation resistant spores produced by many Gram-positive species. Less characterized are dormant cysts produced by several Gram-negative species that are somewhat tolerant to increased temperature and very resistant to desiccation. While there is progress in understanding regulatory circuits that control spore germination, there is scarce information on how Gram-negative organisms emerges from dormancy. In this study, we show that R. centenum cysts germinate by emerging a pair of motile vegetative cells from a thick cyst cell wall coat ~ 6 hrs post induction of germination. Time-lapse transcriptomic analysis reveals that there is a defined temporal pattern of gene expression changes during R. centenum cyst germination. The first observable changes are increases in expression of genes for protein synthesis, an increase in expression of genes involved in the generation of a membrane potential and the use of this potential for ATP synthesis via ATPase expression. These early events are followed by expression changes that affect the cell wall and membrane composition, followed by expression changes that promote chromosome replication. Midway through germination, expression changes occur that promote the flow of carbon through the TCA cycle to generate reducing power and parallel synthesis of electron transfer components involved in oxidative phosphorylation. Finally, late expression changes promote the synthesis of a photosystem as well as flagellar and chemotaxis components for motility.
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Affiliation(s)
- Nandhini Ashok
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Carl E. Bauer
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, United States of America
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7
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De Luca G, Fochesato S, Lavergne J, Forest KT, Barakat M, Ortet P, Achouak W, Heulin T, Verméglio A. Light on the cell cycle of the non-photosynthetic bacterium Ramlibacter tataouinensis. Sci Rep 2019; 9:16505. [PMID: 31712689 PMCID: PMC6848086 DOI: 10.1038/s41598-019-52927-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 10/22/2019] [Indexed: 12/27/2022] Open
Abstract
Ramlibacter tataouinensis TTB310, a non-photosynthetic betaproteobacterium isolated from a semi-arid region of southern Tunisia, forms both rods and cysts. Cysts are resistant to desiccation and divide when water and nutrients are available. Rods are motile and capable of dissemination. Due to the strong correlation between sunlight and desiccation, light is probably an important external signal for anticipating desiccating conditions. Six genes encoding potential light sensors were identified in strain TTB310. Two genes encode for bacteriophytochromes, while the four remaining genes encode for putative blue light receptors. We determined the spectral and photochemical properties of the two recombinant bacteriophytochromes RtBphP1 and RtBphP2. In both cases, they act as sensitive red light detectors. Cyst divisions and a complete cyst-rod-cyst cycle are the main processes in darkness, whereas rod divisions predominate in red or far-red light. Mutant phenotypes caused by the inactivation of genes encoding bacteriophytochromes or heme oxygenase clearly show that both bacteriophytochromes are involved in regulating the rod-rod division. This process could favor rapid rod divisions at sunrise, after dew formation but before the progressive onset of desiccation. Our study provides the first evidence of a light-based strategy evolved in a non-photosynthetic bacterium to exploit scarse water in a desert environment.
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Affiliation(s)
- Gilles De Luca
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMiRE, Saint Paul-Lez-Durance, F-13108, France
| | - Sylvain Fochesato
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMiRE, Saint Paul-Lez-Durance, F-13108, France
| | - Jérôme Lavergne
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMiRE, Saint Paul-Lez-Durance, F-13108, France
| | - Katrina T Forest
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Mohamed Barakat
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMiRE, Saint Paul-Lez-Durance, F-13108, France
| | - Philippe Ortet
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMiRE, Saint Paul-Lez-Durance, F-13108, France
| | - Wafa Achouak
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMiRE, Saint Paul-Lez-Durance, F-13108, France
| | - Thierry Heulin
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMiRE, Saint Paul-Lez-Durance, F-13108, France.
| | - André Verméglio
- Aix Marseille Univ, CEA, CNRS, BIAM, LEMiRE, Saint Paul-Lez-Durance, F-13108, France
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8
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Farrow JM, Wells G, Pesci EC. Desiccation tolerance in Acinetobacter baumannii is mediated by the two-component response regulator BfmR. PLoS One 2018; 13:e0205638. [PMID: 30308034 PMCID: PMC6181384 DOI: 10.1371/journal.pone.0205638] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 09/28/2018] [Indexed: 12/03/2022] Open
Abstract
For the opportunistic pathogen Acinetobacter baumannii, desiccation tolerance is thought to contribute significantly to the persistence of these bacteria in the healthcare environment. We investigated the ability of A. baumannii to survive rapid drying, and found that some strains exhibited a profoundly desiccation-resistant phenotype, characterized by the ability of a large proportion of cells to survive on a dry surface for an extended period of time. However, this phenotype was only displayed during the stationary phase of growth. Most interestingly, we found that drying resistance could be lost after extended cultivation in liquid medium. Genome sequencing of isolates that became drying-sensitive identified mutations in bfmR, which encodes a two-component response regulator that is important for A. baumannii virulence. Additionally, BfmR was necessary for the expression of stress-related proteins during stationary phase, and one of these, KatE, was important for long-term drying survival. These results suggested that BfmR may control stress responses, and we demonstrated that the ΔbfmR mutant was more sensitive to hydrogen peroxide, nutrient starvation, and increased osmolarity. We also found that cross-protection against drying could be stimulated by either starvation, which required BfmR, or increased osmolarity. These results imply that BfmR plays a role in controlling stress responses in A. baumannii which help protect cells during desiccation, and they provide a regulatory link between this organism’s ability to persist in the environment and pathogenicity.
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Affiliation(s)
- John M. Farrow
- Department of Microbiology and Immunology, The Brody School of Medicine at East Carolina University, Greenville, North Carolina, United States of America
| | - Greg Wells
- Department of Microbiology and Immunology, The Brody School of Medicine at East Carolina University, Greenville, North Carolina, United States of America
| | - Everett C. Pesci
- Department of Microbiology and Immunology, The Brody School of Medicine at East Carolina University, Greenville, North Carolina, United States of America
- * E-mail:
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Chowdhury-Paul S, Pando-Robles V, Jiménez-Jacinto V, Segura D, Espín G, Núñez C. Proteomic analysis revealed proteins induced upon Azotobacter vinelandii encystment. J Proteomics 2018; 181:47-59. [PMID: 29605291 DOI: 10.1016/j.jprot.2018.03.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 03/09/2018] [Accepted: 03/27/2018] [Indexed: 01/22/2023]
Affiliation(s)
- Sangita Chowdhury-Paul
- Departamento de Microbiología Molecular, Instituto de Biotecnología, UNAM, Av. Universidad, 2001, Col Chamilpa, C.P. 62210 Cuernavaca, Morelos, México
| | - Victoria Pando-Robles
- Instituto Nacional de Salud Pública, Centro de Investigación Sobre Enfermedades Infecciosas (CISEI), Universidad No. 655 Colonia Santa María Ahuacatitlán, Cerrada Los Pinos y Caminera, C.P. 62100 Cuernavaca, Morelos, México
| | - Verónica Jiménez-Jacinto
- Unidad Universitaria de Secuenciación Masiva y Bioinformática, Instituto de Biotecnologia, UNAM, Av. Universidad, 2001, Col Chamilpa, C.P. 62210 Cuernavaca, Morelos, México
| | - Daniel Segura
- Departamento de Microbiología Molecular, Instituto de Biotecnología, UNAM, Av. Universidad, 2001, Col Chamilpa, C.P. 62210 Cuernavaca, Morelos, México
| | - Guadalupe Espín
- Departamento de Microbiología Molecular, Instituto de Biotecnología, UNAM, Av. Universidad, 2001, Col Chamilpa, C.P. 62210 Cuernavaca, Morelos, México
| | - Cinthia Núñez
- Departamento de Microbiología Molecular, Instituto de Biotecnología, UNAM, Av. Universidad, 2001, Col Chamilpa, C.P. 62210 Cuernavaca, Morelos, México.
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10
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Zhang J, Yuan J, Zhang WX, Tu F, Jiang Y, Sun CZ. Anaerobic detoxification fermentation by Rhodospirillum rubrum for rice straw as feed with moderate pretreatment. Prep Biochem Biotechnol 2018; 48:75-83. [PMID: 29194020 DOI: 10.1080/10826068.2017.1405023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A novel and effective process was put forward for converting rice straw into feed by combining diluted acid hydrolysis and ammonization with Rhodospirillum rubrum fermentation. After pretreatment with dilute sulfuric or phosphoric acid (1%, w/w) at 100°C, materials were subjected to fermentation under several gases (N2, CO2, and air) and different light intensities in a 2-L fermentor. The key indexes of feed for fermented materials were estimated and several toxic substances were investigated during the fermentation. Following sulfuric acid treatment, the true protein of rice straw increased from 29 to 143 g kg-1 and the crude fiber decreased from 359 to 136 g kg-1 after fermentation at 0.3 L min-1 L-1 of N2 flow and a light intensity of 3400 lux; and following phosphoric acid treatment, the true protein increased by 286% and the crude fiber decreased by 52% after fermentation at 0.4 L min-1 L-1 of N2 flow and a light intensity of 3000 lux. Other key contents were also improved for use as feed, and some toxic substances (i.e., furfural, hydroxymethylfurfural, acetic acid, phenol, cresol) produced by the pretreatments could be removed at low levels during the fermentations.
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Affiliation(s)
- Jian Zhang
- a Department of Life Science and Food Engineering/Key Laboratory of Fermentation Resource and Application in Sichuan/Department of Library , Yibin University , Yibin , Sichuan , China
| | - Jie Yuan
- a Department of Life Science and Food Engineering/Key Laboratory of Fermentation Resource and Application in Sichuan/Department of Library , Yibin University , Yibin , Sichuan , China
| | - Wen-Xue Zhang
- b Food microbiology laboratory, College of Light Industry, Textile and Food Engineering , Sichuan University , Chengdu , Sichuan , China
| | - Fang Tu
- a Department of Life Science and Food Engineering/Key Laboratory of Fermentation Resource and Application in Sichuan/Department of Library , Yibin University , Yibin , Sichuan , China
| | - Ya Jiang
- a Department of Life Science and Food Engineering/Key Laboratory of Fermentation Resource and Application in Sichuan/Department of Library , Yibin University , Yibin , Sichuan , China
| | - Chuan-Ze Sun
- c Production Department , Xu Fu Liquor Company , Yibin , Sichuan , China
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11
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Zhang J, Yuan J, Zhang WX, Zhu WY, Tu F, Jiang Y, Sun CZ. An aerobic detoxification photofermentation by Rhodospirillum rubrum for converting soy sauce residue into feed with moderate pretreatment. World J Microbiol Biotechnol 2017; 33:184. [DOI: 10.1007/s11274-017-2344-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 09/16/2017] [Indexed: 10/18/2022]
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12
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Wang D, Xu A, Elmerich C, Ma LZ. Biofilm formation enables free-living nitrogen-fixing rhizobacteria to fix nitrogen under aerobic conditions. ISME JOURNAL 2017; 11:1602-1613. [PMID: 28338674 DOI: 10.1038/ismej.2017.30] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Revised: 12/26/2016] [Accepted: 01/22/2017] [Indexed: 12/14/2022]
Abstract
The multicellular communities of microorganisms known as biofilms are of high significance in agricultural setting, yet it is largely unknown about the biofilm formed by nitrogen-fixing bacteria. Here we report the biofilm formation by Pseudomonas stutzeri A1501, a free-living rhizospheric bacterium, capable of fixing nitrogen under microaerobic and nitrogen-limiting conditions. P. stutzeri A1501 tended to form biofilm in minimal media, especially under nitrogen depletion condition. Under such growth condition, the biofilms formed at the air-liquid interface (termed as pellicles) and the colony biofilms on agar plates exhibited nitrogenase activity in air. The two kinds of biofilms both contained large ovoid shape 'cells' that were multiple living bacteria embedded in a sac of extracellular polymeric substances (EPSs). We proposed to name such large 'cells' as A1501 cyst. Our results suggest that the EPS, especially exopolysaccharides enabled the encased bacteria to fix nitrogen while grown under aerobic condition. The formation of A1501 cysts was reversible in response to the changes of carbon or nitrogen source status. A1501 cyst formation depended on nitrogen-limiting signaling and the presence of sufficient carbon sources, yet was independent of an active nitrogenase. The pellicles formed by Azospirillum brasilense, another free-living nitrogen-fixing rhizobacterium, which also exhibited nitrogenase activity and contained the large EPS-encapsuled A1501 cyst-like 'cells'. Our data imply that free-living nitrogen-fixing bacteria could convert the easy-used carbon sources to exopolysaccharides in order to enable nitrogen fixation in a natural aerobic environment.
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Affiliation(s)
- Di Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Anming Xu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | | | - Luyan Z Ma
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
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13
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Keane R, Berleman J. The predatory life cycle of Myxococcus xanthus. Microbiology (Reading) 2016; 162:1-11. [DOI: 10.1099/mic.0.000208] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Ryan Keane
- Department of Biology, Saint Mary's College, Moraga, CA 94556, USA
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - James Berleman
- Department of Biology, Saint Mary's College, Moraga, CA 94556, USA
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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Dong Q, Fang M, Roychowdhury S, Bauer CE. Mapping the CgrA regulon of Rhodospirillum centenum reveals a hierarchal network controlling Gram-negative cyst development. BMC Genomics 2015; 16:1066. [PMID: 26673205 PMCID: PMC4681086 DOI: 10.1186/s12864-015-2248-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 11/27/2015] [Indexed: 01/24/2023] Open
Abstract
Background Several Gram-negative species undergo development leading to the formation of metabolically dormant desiccation resistant cysts. Recent analysis of cyst development has revealed that ~20 % of the Rhodospirillum centenum transcriptome undergo temporal changes in expression as cells transition from vegetative to cyst forms. It has also been established that one trigger for cyst formation is the synthesis of the signaling nucleotide 3‘, 5‘- cyclic guanosine monophosphate (cGMP) that is sensed by a homolog of the catabolite repressor protein called CgrA. CgrA in the presence of cGMP initiate a cascade of gene expression leading to the development of cysts. Results In this study, we have used RNA-seq and chromatin immunoprecipitation (ChIP-Seq) techniques to define the CgrA-cGMP regulon. Our results indicate that disruption of CgrA leads to altered expression of 258 genes, 131 of which have been previously reported to be involved in cyst development. ChIP-seq analysis combined with transcriptome data also demonstrates that CgrA directly regulates the expression of numerous sigma factors and transcription factors several of which are known to be involved in cyst cell development. Conclusions This analysis reveals the presence of CgrA binding sites upstream of many developmentally regulated genes including many transcription factors and signal transduction components. CgrA thus functions as master controller of the cyst development by initiating a hierarchal cascade of downstream transcription factors that induces temporal expression of encystment genes. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-2248-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Qian Dong
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN, 47405, USA.
| | - Mingxu Fang
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN, 47405, USA.
| | - Sugata Roychowdhury
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN, 47405, USA. .,Present address: Owensboro Cancer Research Program, University of Louisville James Graham Brown Cancer Center, Owensboro, KY, 42303, USA.
| | - Carl E Bauer
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN, 47405, USA. .,Department of Molecular and Cellular Biochemistry, Indiana University, Simon Hall MSB, 212 S. Hawthorne Drive, Bloomington, IN, 47405-7003, USA.
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15
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Roychowdhury S, Dong Q, Bauer CE. DNA-binding properties of a cGMP-binding CRP homologue that controls development of metabolically dormant cysts of Rhodospirillum centenum. MICROBIOLOGY-SGM 2015; 161:2256-64. [PMID: 26362215 DOI: 10.1099/mic.0.000172] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Rhodospirillum centenum utilizes 3',5'-cyclic guanosine monophosphate (cGMP) as a messenger to regulate development of desiccation-resistant cysts. In this study, we demonstrated that gcyA, gcyB and gcyC, coding for putative subunits of a guanylyl cyclase, increase expression from 8- to 500-fold when cells transition from vegetative to cyst phases of growth. This induction did not occur in a strain that is defective in cGMP synthesis or in a strain that contains a deletion of cgrA that codes for a cGMP-binding homologue of Escherichia coli catabolite repressor protein (CRP). We also demonstrated that cgrA auto-induces its own expression in the presence of cGMP, indicating that a feed-forward loop is used to ramp up cGMP production as cells undergo encystment. Inspection of an intragenic region upstream of gcyB revealed a sequence that is identical to the CRP consensus sequence from E. coli. DNase I and fluorescence anisotropy analyses demonstrated that CgrA bound to this target sequence at a protein : cGMP ratio of 1 : 2 with Kd ∼61 nM. This was in contrast to CgrA in the presence of cAMP, which exhibited Kd ∼1795 nM. CgrA thus constitutes a novel variant of CRP that utilizes cGMP to regulate production of cGMP synthase for the control of cyst development.
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Affiliation(s)
- Sugata Roychowdhury
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA
| | - Qian Dong
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA
| | - Carl E Bauer
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA
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16
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Zheng H, Dietrich C, Radek R, Brune A. Endomicrobium proavitum, the first isolate of Endomicrobia class. nov. (phylum Elusimicrobia)--an ultramicrobacterium with an unusual cell cycle that fixes nitrogen with a Group IV nitrogenase. Environ Microbiol 2015; 18:191-204. [PMID: 26119974 DOI: 10.1111/1462-2920.12960] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 06/16/2015] [Accepted: 06/16/2015] [Indexed: 11/28/2022]
Abstract
The bacterial tree contains many deep-rooting clades without any cultured representatives. One such clade is 'Endomicrobia', a class-level lineage in the phylum Elusimicrobia represented so far only by intracellular symbionts of termite gut flagellates. Here, we report the isolation and characterization of the first free-living member of this clade from sterile-filtered gut homogenate of defaunated (starch-fed) Reticulitermes santonensis. Strain Rsa215 is a strictly anaerobic ultramicrobacterium that grows exclusively on glucose, which is fermented to lactate, acetate, hydrogen and CO2. Ultrastructural analysis revealed a Gram-negative cell envelope and a peculiar cell cycle. The genome contains a single set of nif genes that encode homologues of Group IV nitrogenases, which were so far considered to have functions other than nitrogen fixation. We documented nitrogenase activity and diazotrophic growth by measuring acetylene reduction activity and (15)N2 incorporation into cell mass, and demonstrated that transcription of nifH and nitrogenase activity occur only in the absence of ammonium. Based on the ancestral relationship to 'Candidatus Endomicrobium trichonymphae' and other obligate endosymbionts, we propose the name 'Endomicrobium proavitum' gen. nov., sp. nov. for the first isolate of this lineage and the name 'Endomicrobia' class. nov. for the entire clade.
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Affiliation(s)
- Hao Zheng
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
| | - Carsten Dietrich
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
| | - Renate Radek
- Institute of Biology/Zoology, Free University of Berlin, Königin-Luise-Strasse 1-3, 14195, Berlin, Germany
| | - Andreas Brune
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany.,LOEWE Center for Synthetic Microbiology, SYNMIKRO, Philipps-Universität Marburg, 35043, Marburg, Germany
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17
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He K, Dragnea V, Bauer CE. Adenylate Charge Regulates Sensor Kinase CheS3 To Control Cyst Formation in Rhodospirillum centenum. mBio 2015; 6:e00546-15. [PMID: 25944862 PMCID: PMC4436063 DOI: 10.1128/mbio.00546-15] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 04/06/2015] [Indexed: 12/02/2022] Open
Abstract
UNLABELLED Rhodospirillum centenum forms metabolically dormant cysts under unfavorable growth conditions such as desiccation or nutrient starvation. The development of cysts is tightly regulated and involves a cyst-repressing chemotaxis-like signal transduction pathway called the Che3 signaling cascade. The Che3 cascade is comprised of a methyl chemoreceptor (MCP3), receptor-methylating/demethylating proteins CheB3 and CheR3, two CheW3 linker proteins, a CheA3-CheY hybrid histidine kinase, and a single-domain response regulator, CheY3. In addition to Che-like components, the Che3 cascade also contains a second hybrid histidine kinase, CheS3. Recent biochemical and genetic studies show that CheA3 does not serve as a phosphor donor for CheY3; instead, CheA3 inhibits a CheS3→CheY3 two-component system by phosphorylating an inhibitory receiver domain of CheS3. In this study, we show that in addition to phosphorylation by CheA3, the phosphorylation state of CheS3 is also regulated by the cellular energy level as quantified by the molar ratio of ATP/(ATP + ADP). A 35% decrease in cellular energy is shown to occur in vivo upon a nutrient downshift that gives rise to cyst formation. When this energy decline is replicated in vitro, the phosphorylation level of CheS3 is reduced by ~75%. Finally, we also show that ADP-mediated reduction of CheS3 phosphorylation is a consequence of ADP enhancing autodephosphorylation of CheS3. IMPORTANCE Upon starvation, Rhodospirillum centenum undergoes a developmental process that forms metabolically dormant cysts, which withstand desiccation and nutritional limitation. This study explores the role of the cellular energy state as measured by the ratio of ATP to ADP as an important regulator of cyst formation in Rhodospirillum centenum. We show that R. centenum cells experience a significant reduction in ATP during cyst formation using ATP/(ATP + ADP) as a measurement. When this in vivo level of energy starvation is simulated in vitro, CheS3 phosphorylation is reduced by 75%. This profound reduction in CheS3 autophosphorylation is contrasted with a much lower 25% decrease in CheA3 phosphorylation in response to a similar downward shift in ATP/(ATP + ADP). We argue that even though adenylate energy affects all ATP-dependent enzymes to an extent, the enhanced inhibition of CheS3 activity in response to a reduction in the ATP/(ATP + ADP) ratio likely functions as an important input signal to regulate cyst development.
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Affiliation(s)
- Kuang He
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, Indiana, USA
| | - Vladimira Dragnea
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, Indiana, USA
| | - Carl E Bauer
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, Indiana, USA
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18
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Francez-Charlot A, Kaczmarczyk A, Vorholt JA. The branched CcsA/CckA-ChpT-CtrA phosphorelay of Sphingomonas melonis controls motility and biofilm formation. Mol Microbiol 2015; 97:47-63. [PMID: 25825287 DOI: 10.1111/mmi.13011] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/28/2015] [Indexed: 11/29/2022]
Abstract
The CckA-ChpT-CtrA phosphorelay is central to the regulation of the cell cycle in Caulobacter crescentus. The three proteins are conserved in Alphaproteobacteria, but little is known about their roles in most members of this class. Here, we characterized the system in Sphingomonas melonis. We found that the transcription factor CtrA is the master regulator of flagella synthesis genes, the hierarchical transcriptional organization of which is herein described. CtrA also regulates genes involved in exopolysaccharide synthesis and cyclic-di-GMP signaling, and is important for biofilm formation. In addition, the ctrA mutant exhibits an aberrant morphology, suggesting a role for CtrA in cell division. An analysis of the regulation of CtrA indicates that the phosphorelay composed of CckA and ChpT is conserved and that the absence of the bifunctional kinase/phosphatase CckA apparently results in overactivation of CtrA through ChpT. Suppressors of this phenotype identified the hybrid histidine kinase CcsA. Phosphorelays initiated by CckA or CcsA were reconstituted in vitro, suggesting that in S. melonis, CtrA phosphorylation is controlled by a branched pathway upstream of ChpT. This study thus suggests that signals can directly converge at the level of ChpT phosphorylation through multiple hybrid kinases to coordinate a number of important physiological processes.
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Affiliation(s)
| | | | - Julia A Vorholt
- Institute of Microbiology, ETH Zurich, 8093, Zurich, Switzerland
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19
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Dong Q, Bauer CE. Transcriptome analysis of cyst formation in Rhodospirillum centenum reveals large global changes in expression during cyst development. BMC Genomics 2015; 16:68. [PMID: 25758168 PMCID: PMC4340629 DOI: 10.1186/s12864-015-1250-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 01/15/2015] [Indexed: 01/11/2023] Open
Abstract
Background Rhodospirillum centenum is a photosynthetic member of the Gram-negative Azospirillum clade members of which exhibit a complex developmental life-cycle featuring morphologically distinct cell types. Under periods of nutrient deprivation, replicative vegetative cells differentiate into metabolically dormant cysts that survive harsh environmental stresses such as desiccation. Encystment involves a multi-stage developmental process that includes the rounding of cells, production of large intracellular storage granules of poly-hydroxybutyrate (PHB) and the excretion of a protective exopolysaccharide coating that envelops dormant cysts. Results To study the process of cyst development, we performed RNA-seq studies on cells that were induced to undergo cyst development. To assay for temporal changes in gene expression, RNA was extracted at 4, 24, 48, 72, 96 hours during development and subjected to deep sequence analysis. These results show that 812 genes exhibit log2 ≥ 1.5-fold changes in expression over a 96 hour cyst induction period demonstrating large global changes in gene expression during cyst development. Conclusions Notable changes in expression occurred in numerous genes involved in cell wall and lipid biosynthesis, metabolic enzymes, and numerous regulatory genes such as histidine kinases and transcription factors. Many genes involved in protein synthesis and DNA replication were also significantly reduced during late stages of cyst development. Genes previously identified by genetic screens as being critical for cyst development also exhibited changes of expression during cyst induction. This study provides the first transcriptome profile of global changes in gene expression that occur during development of cysts in a Gram-negative species. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1250-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Qian Dong
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN, 47405, USA.
| | - Carl E Bauer
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN, 47405, USA.
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20
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He K, Bauer CE. Chemosensory signaling systems that control bacterial survival. Trends Microbiol 2014; 22:389-98. [PMID: 24794732 DOI: 10.1016/j.tim.2014.04.004] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 03/28/2014] [Accepted: 04/08/2014] [Indexed: 11/28/2022]
Abstract
Recent studies have revealed that several Gram-negative species utilize variations of the well-known chemotaxis signaling cascade to switch lifestyles in order to survive environmental stress. The two survival strategies covered in this review are the development of dormant cyst cells and biofilm formation. Each of these structures involves exopolysaccharide-mediated cell-cell interactions, which result in multicellular communities that confer resistance to stress conditions such as desiccation and antibiotics. This review is centered on recent advances in the understanding of phosphate flow and novel output signals in chemosensory signaling pathways that are involved in cyst formation and biofilms.
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Affiliation(s)
- Kuang He
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - Carl E Bauer
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA.
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21
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Global analysis of cell cycle gene expression of the legume symbiont Sinorhizobium meliloti. Proc Natl Acad Sci U S A 2014; 111:3217-24. [PMID: 24501121 DOI: 10.1073/pnas.1400421111] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In α-proteobacteria, strict regulation of cell cycle progression is necessary for the specific cellular differentiation required for adaptation to diverse environmental niches. The symbiotic lifestyle of Sinorhizobium meliloti requires a drastic cellular differentiation that includes genome amplification. To achieve polyploidy, the S. meliloti cell cycle program must be altered to uncouple DNA replication from cell division. In the α-proteobacterium Caulobacter crescentus, cell cycle-regulated transcription plays an important role in the control of cell cycle progression but this has not been demonstrated in other α-proteobacteria. Here we describe a robust method for synchronizing cell growth that enabled global analysis of S. meliloti cell cycle-regulated gene expression. This analysis identified 462 genes with cell cycle-regulated transcripts, including several key cell cycle regulators, and genes involved in motility, attachment, and cell division. Only 28% of the 462 S. meliloti cell cycle-regulated genes were also transcriptionally cell cycle-regulated in C. crescentus. Furthermore, CtrA- and DnaA-binding motif analysis revealed little overlap between the cell cycle-dependent regulons of CtrA and DnaA in S. meliloti and C. crescentus. The predicted S. meliloti cell cycle regulon of CtrA, but not that of DnaA, was strongly conserved in more closely related α-proteobacteria with similar ecological niches as S. meliloti, suggesting that the CtrA cell cycle regulatory network may control functions of central importance to the specific lifestyles of α-proteobacteria.
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22
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He K, Marden JN, Quardokus EM, Bauer CE. Phosphate flow between hybrid histidine kinases CheA₃ and CheS₃ controls Rhodospirillum centenum cyst formation. PLoS Genet 2013; 9:e1004002. [PMID: 24367276 PMCID: PMC3868531 DOI: 10.1371/journal.pgen.1004002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 10/21/2013] [Indexed: 01/21/2023] Open
Abstract
Genomic and genetic analyses have demonstrated that many species contain multiple chemotaxis-like signal transduction cascades that likely control processes other than chemotaxis. The Che3 signal transduction cascade from Rhodospirillum centenum is one such example that regulates development of dormant cysts. This Che-like cascade contains two hybrid response regulator-histidine kinases, CheA3 and CheS3, and a single-domain response regulator CheY3. We demonstrate that cheS3 is epistatic to cheA3 and that only CheS3∼P can phosphorylate CheY3. We further show that CheA3 derepresses cyst formation by phosphorylating a CheS3 receiver domain. These results demonstrate that the flow of phosphate as defined by the paradigm E. coli chemotaxis cascade does not necessarily hold true for non-chemotactic Che-like signal transduction cascades. Bacteria use chemotaxis and chemotaxis-like signal transduction pathways to quickly sense and adapt to a constantly changing environment. The purple photosynthetic bacterium Rhodospirillum centenum is able to withstand long periods of desiccation by forming metabolically dormant cyst cells, the development of which is regulated by the Che3 chemotaxis-like pathway. Using a combination of genetic and biochemical approaches, we demonstrate that hybrid histidine kinase (HHK) CheA3 encoded in the che3 gene cluster is essential for cyst formation while another HHK CheS3 inhibits cyst formation. We further show that the appended receiver domains of these kinases regulate their respective histidine kinase domains and are critical in controlling the timing of cyst formation. Finally, we demonstrate that CheA3 functions upstream of CheS3 and promotes cyst formation by phosphorylating CheS3.
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Affiliation(s)
- Kuang He
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, Indiana, United States of America
| | - Jeremiah N. Marden
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, Indiana, United States of America
| | - Ellen M. Quardokus
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Carl E. Bauer
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, Indiana, United States of America
- * E-mail:
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Awakawa T, Sugai Y, Otsutomo K, Ren S, Masuda S, Katsuyama Y, Horinouchi S, Ohnishi Y. 4-Hydroxy-3-methyl-6-(1-methyl-2-oxoalkyl)pyran-2-one synthesis by a type III polyketide synthase from Rhodospirillum centenum. Chembiochem 2013; 14:1006-13. [PMID: 23609937 DOI: 10.1002/cbic.201300066] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Indexed: 11/12/2022]
Abstract
The purple photosynthetic bacterium Rhodospirillum centenum has a putative type III polyketide synthase gene (rpsA). Although rpsA was known to be transcribed during the formation of dormant cells, the reaction catalyzed by RpsA was unknown. Thus we examined the RpsA reaction in vitro, using various fatty acyl-CoAs with even numbers of carbons as starter substrates. RpsA produced tetraketide pyranones as major compounds from one C(10-14) fatty acyl-CoA unit, one malonyl-CoA unit and two methylmalonyl-CoA units. We identified these products as 4-hydroxy-3-methyl-6-(1-methyl-2-oxoalkyl)pyran-2-ones by NMR analysis. RpsA is the first bacterial type III PKS that prefers to incorporate two molecules of methylmalonyl-CoA as the extender substrate. In addition, in vitro reactions with (13)C-labeled malonyl-CoA revealed that RpsA produced tetraketide 6-alkyl-4-hydroxy-1,5-dimethyl-2-oxocyclohexa-3,5-diene-1-carboxylic acids from C(14-20) fatty acyl-CoAs. This class of compounds is likely synthesized through aldol condensation induced by methine proton abstraction. No type III polyketide synthase that catalyzes this reaction has been reported so far. These two unusual features of RpsA extend the catalytic functions of the type III polyketide synthase family.
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Affiliation(s)
- Takayoshi Awakawa
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
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Parro V, de Diego-Castilla G, Moreno-Paz M, Blanco Y, Cruz-Gil P, Rodríguez-Manfredi JA, Fernández-Remolar D, Gómez F, Gómez MJ, Rivas LA, Demergasso C, Echeverría A, Urtuvia VN, Ruiz-Bermejo M, García-Villadangos M, Postigo M, Sánchez-Román M, Chong-Díaz G, Gómez-Elvira J. A microbial oasis in the hypersaline Atacama subsurface discovered by a life detector chip: implications for the search for life on Mars. ASTROBIOLOGY 2011; 11:969-96. [PMID: 22149750 PMCID: PMC3242637 DOI: 10.1089/ast.2011.0654] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 09/01/2011] [Indexed: 05/04/2023]
Abstract
The Atacama Desert has long been considered a good Mars analogue for testing instrumentation for planetary exploration, but very few data (if any) have been reported about the geomicrobiology of its salt-rich subsurface. We performed a Mars analogue drilling campaign next to the Salar Grande (Atacama, Chile) in July 2009, and several cores and powder samples from up to 5 m deep were analyzed in situ with LDChip300 (a Life Detector Chip containing 300 antibodies). Here, we show the discovery of a hypersaline subsurface microbial habitat associated with halite-, nitrate-, and perchlorate-containing salts at 2 m deep. LDChip300 detected bacteria, archaea, and other biological material (DNA, exopolysaccharides, some peptides) from the analysis of less than 0.5 g of ground core sample. The results were supported by oligonucleotide microarray hybridization in the field and finally confirmed by molecular phylogenetic analysis and direct visualization of microbial cells bound to halite crystals in the laboratory. Geochemical analyses revealed a habitat with abundant hygroscopic salts like halite (up to 260 g kg(-1)) and perchlorate (41.13 μg g(-1) maximum), which allow deliquescence events at low relative humidity. Thin liquid water films would permit microbes to proliferate by using detected organic acids like acetate (19.14 μg g(-1)) or formate (76.06 μg g(-1)) as electron donors, and sulfate (15875 μg g(-1)), nitrate (13490 μg g(-1)), or perchlorate as acceptors. Our results correlate with the discovery of similar hygroscopic salts and possible deliquescence processes on Mars, and open new search strategies for subsurface martian biota. The performance demonstrated by our LDChip300 validates this technology for planetary exploration, particularly for the search for life on Mars.
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Affiliation(s)
- Victor Parro
- Department of Molecular Evolution, Centro de Astrobiología (INTA-CSIC), Madrid, Spain.
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Bird TH, MacKrell A. A CtrA homolog affects swarming motility and encystment in Rhodospirillum centenum. Arch Microbiol 2011; 193:451-9. [PMID: 21243338 DOI: 10.1007/s00203-011-0676-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 12/19/2010] [Accepted: 12/23/2010] [Indexed: 11/29/2022]
Abstract
The α-proteobacterium, Rhodospirillum centenum, has a complex life cycle that allows adaptation to different environments. Transitions between vegetative swim cell and swarmer cell types depend on whether the organism is growing in liquid surroundings or on a solid substrate. Moreover, starvation can induce vegetative cells to differentiate into quiescent cysts. This paper describes the results of our investigation into the role of a putative DNA-binding response regulator that is homologous to CtrA, the cell cycle regulator from Caulobacter crescentus. Deletion of ctrA from the R. centenum genome resulted in a viable strain with impaired swarming motility coupled with an increased tendency to form cysts. Conversely, overexpression of wild type CtrA or a phosphomimetic allele, CtrAD51E, suppressed cyst cell formation, whereas overexpression of a CtrAD51A allele failed to suppress encystment but did prevent swarming motility. Thus, we propose that CtrA participates within a two-component signal transduction pathway that promotes swarming motility while contributing to the suppression of cyst cell formation.
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Affiliation(s)
- Terry H Bird
- Biology Department, University of San Diego, San Diego, CA 92110, USA.
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Marden JN, Dong Q, Roychowdhury S, Berleman JE, Bauer CE. Cyclic GMP controls Rhodospirillum centenum cyst development. Mol Microbiol 2011; 79:600-15. [PMID: 21214648 DOI: 10.1111/j.1365-2958.2010.07513.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Adenylyl cyclases are widely distributed across all kingdoms whereas guanylyl cyclases are generally thought to be restricted to eukaryotes. Here we report that the α-proteobacterium Rhodospirillum centenum secretes cGMP when developing cysts and that a guanylyl cyclase deletion strain fails to synthesize cGMP and is defective in cyst formation. The R. centenum cyclase was purified and shown to effectively synthesize cGMP from GTP in vitro, demonstrating that it is a functional guanylyl cyclase. A homologue of the Escherichia coli cAMP receptor protein (CRP) is linked to the guanylyl cyclase and when deleted is deficient in cyst development. Isothermal calorimetry (ITC) and differential scanning fluorimetry (DSF) analyses demonstrate that the recombinant CRP homologue preferentially binds to, and is stabilized by cGMP, but not cAMP. This study thus provides evidence that cGMP has a crucial role in regulating prokaryotic development. The involvement of cGMP in regulating bacterial development has broader implications as several plant-interacting bacteria contain a similar cyclase coupled by the observation that Azospirillum brasilense also synthesizes cGMP when inducing cysts.
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Affiliation(s)
- Jeremiah N Marden
- Indiana University, Bloomington, IN 47405, USA University of California at Berkeley, Berkeley, CA 94720, USA
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Din N, Shoemaker CJ, Akin KL, Frederick C, Bird TH. Two putative histidine kinases are required for cyst formation in Rhodospirillum Centenum. Arch Microbiol 2010; 193:209-22. [PMID: 21184217 DOI: 10.1007/s00203-010-0664-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 11/17/2010] [Accepted: 11/22/2010] [Indexed: 10/18/2022]
Abstract
The photosynthetic bacterium, Rhodospirillum centenum, has a flexible life cycle that permits it to survive starvation as dormant cyst cells. Previous studies have identified some of the key regulators for encystment and demonstrated that the control of development is intricate. This complexity may arise from the need to integrate several environmental signals to mediate a switch from one mode of energy metabolism to another and to ensure that a transition to dormancy is initiated only when necessary. We searched for additional regulators of development by screening for encystment deficient strains after subjecting wild type R. centenum to mini-Tn5 mutagenesis. Analysis of "hypo-cyst" strains led to the identification of two genes that encode putative hybrid histidine kinases (cyd1 and cyd2). Cells with deletions of either gene fail to form cysts under conditions that normally induce development. Furthermore, the deletion strains exhibit altered swarming behavior suggesting that Cyd1 and Cyd2 affect behaviors utilized when the organism is attached to a substrate.
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Affiliation(s)
- Neena Din
- Biology Department, University of San Diego, 5998 Alcalá Park, San Diego, CA 92110, USA
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Gliding motility revisited: how do the myxobacteria move without flagella? Microbiol Mol Biol Rev 2010; 74:229-49. [PMID: 20508248 DOI: 10.1128/mmbr.00043-09] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In bacteria, motility is important for a wide variety of biological functions such as virulence, fruiting body formation, and biofilm formation. While most bacteria move by using specialized appendages, usually external or periplasmic flagella, some bacteria use other mechanisms for their movements that are less well characterized. These mechanisms do not always exhibit obvious motility structures. Myxococcus xanthus is a motile bacterium that does not produce flagella but glides slowly over solid surfaces. How M. xanthus moves has remained a puzzle that has challenged microbiologists for over 50 years. Fortunately, recent advances in the analysis of motility mutants, bioinformatics, and protein localization have revealed likely mechanisms for the two M. xanthus motility systems. These results are summarized in this review.
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Lu YK, Marden J, Han M, Swingley WD, Mastrian SD, Chowdhury SR, Hao J, Helmy T, Kim S, Kurdoglu AA, Matthies HJ, Rollo D, Stothard P, Blankenship RE, Bauer CE, Touchman JW. Metabolic flexibility revealed in the genome of the cyst-forming alpha-1 proteobacterium Rhodospirillum centenum. BMC Genomics 2010; 11:325. [PMID: 20500872 PMCID: PMC2890560 DOI: 10.1186/1471-2164-11-325] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Accepted: 05/25/2010] [Indexed: 11/23/2022] Open
Abstract
Background Rhodospirillum centenum is a photosynthetic non-sulfur purple bacterium that favors growth in an anoxygenic, photosynthetic N2-fixing environment. It is emerging as a genetically amenable model organism for molecular genetic analysis of cyst formation, photosynthesis, phototaxis, and cellular development. Here, we present an analysis of the genome of this bacterium. Results R. centenum contains a singular circular chromosome of 4,355,548 base pairs in size harboring 4,105 genes. It has an intact Calvin cycle with two forms of Rubisco, as well as a gene encoding phosphoenolpyruvate carboxylase (PEPC) for mixotrophic CO2 fixation. This dual carbon-fixation system may be required for regulating internal carbon flux to facilitate bacterial nitrogen assimilation. Enzymatic reactions associated with arsenate and mercuric detoxification are rare or unique compared to other purple bacteria. Among numerous newly identified signal transduction proteins, of particular interest is a putative bacteriophytochrome that is phylogenetically distinct from a previously characterized R. centenum phytochrome, Ppr. Genes encoding proteins involved in chemotaxis as well as a sophisticated dual flagellar system have also been mapped. Conclusions Remarkable metabolic versatility and a superior capability for photoautotrophic carbon assimilation is evident in R. centenum.
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Affiliation(s)
- Yih-Kuang Lu
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
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Kyndt JA, Fitch JC, Seibeck S, Borucki B, Heyn MP, Meyer TE, Cusanovich MA. Regulation of the Ppr Histidine Kinase by Light-Induced Interactions between Its Photoactive Yellow Protein and Bacteriophytochrome Domains. Biochemistry 2010; 49:1744-54. [DOI: 10.1021/bi901591m] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- John A. Kyndt
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721
| | - John C. Fitch
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721
| | - Sven Seibeck
- Biophysics group, Department of Physics, Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Berthold Borucki
- Biophysics group, Department of Physics, Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Maarten P. Heyn
- Biophysics group, Department of Physics, Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Terry E. Meyer
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721
| | - Michael A. Cusanovich
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721
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Kaplan-Levy RN, Hadas O, Summers ML, Rücker J, Sukenik A. Akinetes: Dormant Cells of Cyanobacteria. DORMANCY AND RESISTANCE IN HARSH ENVIRONMENTS 2010. [DOI: 10.1007/978-3-642-12422-8_2] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Girija KR, Sasikala C, Ramana CV, Spröer C, Takaichi S, Thiel V, Imhoff JF. Rhodobacter johrii sp. nov., an endospore-producing cryptic species isolated from semi-arid tropical soils. Int J Syst Evol Microbiol 2009; 60:2099-2107. [PMID: 19854875 DOI: 10.1099/ijs.0.011718-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
An oval to rod-shaped, phototrophic, purple non-sulfur bacterium, strain JA192(T), was isolated from an enrichment culture of a pasteurized rhizosphere soil sample from a field cultivated with jowar (sorghum) collected from Godumakunta village near Hyderabad, India. Strain JA192(T) is Gram-negative, motile and produces endospores. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that the strain JA192(T) is closely related to Rhodobacter sphaeroides 2.4.1(T) (99.9 % sequence similarity), Rba. megalophilus JA194(T) (99.8 %) and Rba. azotoformans KA25(T) (98.1 %) and clusters with other species of the genus Rhodobacter of the family Rhodobacteraceae. However, DNA-DNA hybridization with Rba. sphaeroides DSM 158(T), Rba. megalophilus JA194(T) and Rba. azotoformans JCM 9340(T) showed relatedness of only 38-57 % with respect to strain JA192(T). On the basis of 16S rRNA gene sequence analysis, DNA-DNA hybridization data and morphological, physiological and chemotaxonomic characters, strain JA192(T) represents a novel species of the genus Rhodobacter, for which the name Rhodobacter johrii sp. nov. is proposed. The type strain is JA192(T) (=DSM 18678(T) =JCM 14543(T) =MTCC 8172(T)).
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Affiliation(s)
- K R Girija
- Bacterial Discovery Laboratory and Resource Centre, Centre for Environment, IST, JNT University, Kukatpally, Hyderabad 500 085, India
| | - Ch Sasikala
- Bacterial Discovery Laboratory and Resource Centre, Centre for Environment, IST, JNT University, Kukatpally, Hyderabad 500 085, India
| | - Ch V Ramana
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, PO Central University, Hyderabad 500 046, India
| | - C Spröer
- DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstraße 7B, 38124 Braunschweig, Germany
| | - S Takaichi
- Department of Biology, Nippon Medical School, Kosugi-cho, Nakahara, Kawasaki 211-0063, Japan
| | - V Thiel
- Leibniz-Institut für Meereswissenschaften IFM-GEOMAR, Marine Mikrobiologie, Düsternbrooker Weg 20, 24105 Kiel, Germany
| | - J F Imhoff
- Leibniz-Institut für Meereswissenschaften IFM-GEOMAR, Marine Mikrobiologie, Düsternbrooker Weg 20, 24105 Kiel, Germany
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Nishijima M, Takadera T, Imamura N, Kasai H, An KD, Adachi K, Nagao T, Sano H, Yamasato K. Microbulbifer variabilis sp. nov. and Microbulbifer epialgicus sp. nov., isolated from Pacific marine algae, possess a rod-coccus cell cycle in association with the growth phase. Int J Syst Evol Microbiol 2009; 59:1696-707. [DOI: 10.1099/ijs.0.006452-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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García-Esquivel G, Calva-Calva G, Ferrera-Cerrato R, Fernández-Linares LC, Vázquez RR, Esparza-García FJ. Encystment of Azotobacter nigricans grown diazotrophically on kerosene as sole carbon source. Arch Microbiol 2008; 191:275-81. [PMID: 19018516 DOI: 10.1007/s00203-008-0444-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Revised: 09/09/2008] [Accepted: 10/27/2008] [Indexed: 11/29/2022]
Abstract
Encystment of Azotobacter nigricans was induced by its diazotrophic cultivation on kerosene. Its growth and nitrogenase activity were affected by kerosene in comparison to cultures grown on sucrose. Electron microscopy of vegetative cells showed that when nitrogenase activity was higher and the poly-beta-hydroxybutyrate granules were not present to a significant extent, peripheral bodies were abundant. After 8 days of culture on kerosene, the presence of cysts with intracellular bunches of poly-beta-hydroxybutyrate granules was observed. Germination of cysts bears germinating multicelled yet unbroken capsule cysts with up to three cells inside. This is the first report of encystment induction of Azotobacter species grown on kerosene.
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Affiliation(s)
- Gabriela García-Esquivel
- Biotechnology and Bioengineering Department, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, C. P. 07360 Mexico D. F., Mexico
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Berleman JE, Bauer CE. A che-like signal transduction cascade involved in controlling flagella biosynthesis in Rhodospirillum centenum. Mol Microbiol 2005; 55:1390-402. [PMID: 15720548 DOI: 10.1111/j.1365-2958.2005.04489.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Rhodospirillum centenum is a photosynthetic bacterium capable of undergoing swim cell to swarm cell differentiation that allows this species to be motile on both liquid and solid media. Previous experiments have demonstrated that the che1 operon is required for the control of chemotactic and phototactic behaviour of both swim and swarm cells. In this report, we analyse the function of a second che-like gene cluster in R. centenum, the che2 gene cluster. In-frame deletion mutants of cheW2, cheB2, cheR2, cheY2, and of the entire che2 operon, exhibit defects in swim and swarm cell motility. Analysis of these strains demonstrates that they are non-motile, and that the non-motile phenotype is resulting from reduced polar and lateral flagella synthesis. Additionally, mutations in mcp2, ORF204, cheA2 and ORF74 remain chemotacticly and phototacticly competent at both high and low growth temperatures. Mutations in these che2 genes result in elevated levels of flagellin proteins giving rise to a hyperflagellate phenotype. We propose a model in which R. centenum utilizes a che-like signal transduction pathway (che2) for regulating flagellum synthesis in order to optimize swim cell-swarm cell differentiation in response to changing environmental conditions.
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Affiliation(s)
- James E Berleman
- School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA
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Berleman JE, Bauer CE. Involvement of a Che-like signal transduction cascade in regulating cyst cell development inRhodospirillum centenum. Mol Microbiol 2005; 56:1457-66. [PMID: 15916598 DOI: 10.1111/j.1365-2958.2005.04646.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Homologues of the E. coli chemotaxis (Che) signal transduction pathway are present in nearly all motile bacteria. Although E. coli contains only one Che cascade, many other bacteria are known to possess multiple sets of che genes. The role of multiple che-like gene clusters could potentially code for parallel Che-like signal transduction pathways that have distinctly different input and output functions. In this study, we describe a che-like gene cluster in Rhodospirillum centenum that controls a developmental cycle. In-frame deletion mutants of homologues of CheW (DeltacheW(3a)and DeltacheW(3b)), CheR (DeltacheR(3)), CheA (DeltacheA(3)) and a methyl-accepting chemotaxis protein (Deltamcp(3)) are defective in starvation-induced formation of heat and desiccation resistant cyst cells. In contrast, mutants of homologues of CheY (DeltacheY(3)), CheB (DeltacheB(3)), and a second input kinase designated as CheS (DeltacheS(3)) result in cells that are derepressed in the formation of cysts. A model of signal transduction is presented in which there are three distinct Che-like signal transduction cascades; one that is involved in chemotaxis, one that is involved in flagella biosynthesis and the third that is involved in cyst development.
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Affiliation(s)
- James E Berleman
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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Berleman JE, Hasselbring BM, Bauer CE. Hypercyst mutants in Rhodospirillum centenum identify regulatory loci involved in cyst cell differentiation. J Bacteriol 2004; 186:5834-41. [PMID: 15317789 PMCID: PMC516826 DOI: 10.1128/jb.186.17.5834-5841.2004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rhodospirillum centenum is a purple photosynthetic bacterium that forms resting cyst cells when starved for nutrients. In this study, we demonstrate that chalcone synthase gene (chsA) expression is developmentally regulated, with expression of chsA increasing up to 86-fold upon induction of the cyst developmental cycle. Screening for mini-Tn5-induced mutants that exhibit elevated chsA::lacZ expression has led to the isolation of a set of R. centenum mutants that display increased chsA gene expression concomitant with constitutive induction of the cyst developmental cycle. These "hypercyst" mutants have lost the ability to regulate cyst cell formation in response to nutrient availability. Sequence analysis indicates that the mini-Tn5-disrupted genes code for a variety of factors, including metabolic enzymes and a large set of potential regulatory factors, including four gene products with homology to histidine sensor kinases and three with homology to response regulators. Several of the disrupted genes also have sequence similarity to che-like signal transduction components.
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Affiliation(s)
- James E Berleman
- Department of Biology, Indiana University, Myers Hall, 915 E. Third St., Bloomington, IN 47405, USA
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