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Xie CJ, Yao L, Tang R, Han S, Yang S, Alwathnani H, Rensing C, Liu GH, Zhou SG. Azotosporobacter soli gen. nov., sp. nov., a novel nitrogen-fixing bacterium isolated from paddy soil. Antonie Van Leeuwenhoek 2024; 117:79. [PMID: 38755437 DOI: 10.1007/s10482-024-01978-6] [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: 02/26/2024] [Accepted: 05/07/2024] [Indexed: 05/18/2024]
Abstract
A nitrogen-fixing strain designated SG130T was isolated from paddy soil in Fujian Province, China. Strain SG130T was Gram-staining-negative, rod-shaped, and strictly anaerobic. Strain SG130T showed the highest 16S rRNA gene sequence similarities with the type strains Dendrosporobacter quercicolus DSM 1736T (91.7%), Anaeroarcus burkinensis DSM 6283T (91.0%) and Anaerospora hongkongensis HKU 15T (90.9%). Furthermore, the phylogenetic and phylogenomic analysis also suggested strain SG130T clustered with members of the family Sporomusaceae and was distinguished from other genera within this family. Growth of strain SG130T was observed at 25-45 °C (optimum 30 °C), pH 6.0-9.5 (optimum 7.0) and 0-1% (w/v) NaCl (optimum 0.1%). The quinones were Q-8 and Q-9. The polar lipids were phosphatidylserine (PS), phosphatidylethanolamine (PE), glycolipid (GL), phospholipid (PL) and an unidentified lipid (UL). The major fatty acids (> 10%) were iso-C13:0 3OH (26.6%), iso-C17:1 (15.6%) and iso-C15:1 F (11.4%). The genomic DNA G + C content was 50.7%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain SG130T and the most closely related type strain D. quercicolus DSM 1736T (ANI 68.0% and dDDH 20.3%) were both below the cut-off level for species delineation. The average amino acid identity (AAI) between strain SG130T and the most closely related type strain D. quercicolus DSM 1736T was 63.2%, which was below the cut-off value for bacterial genus delineation (65%). Strain SG130T possessed core genes (nifHDK) involved in nitrogen fixation, and nitrogenase activity (106.38 μmol C2H4 g-1 protein h-1) was examined using the acetylene reduction assay. Based on the above results, strain SG130T is confirmed to represent a novel genus of the family Sporomusaceae, for which the name Azotosporobacter soli gen. nov., sp. nov. is proposed. The type strain is SG130T (= GDMCC 1.3312T = JCM 35641T).
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Affiliation(s)
- Cheng-Jie Xie
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, Fujian Province, 350002, People's Republic of China
| | - Ling Yao
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, Fujian Province, 350002, People's Republic of China
| | - Rong Tang
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou City, Guangdong Province, 510006, People's Republic of China
| | - Shuang Han
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, Fujian Province, 350002, People's Republic of China
| | - Shang Yang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, Fujian Province, 350002, People's Republic of China
| | - Hend Alwathnani
- Department of Botany and Microbiology, King Saud University, Riyadh, Saudi Arabia
| | - Christopher Rensing
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, Fujian Province, 350002, People's Republic of China
| | - Guo-Hong Liu
- Institute of Resources, Environment and Soil Fertilizer, Fujian Academy of Agricultural Sciences, Fuzhou City, Fujian Province, 350003, People's Republic of China.
| | - Shun-Gui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, Fujian Province, 350002, People's Republic of China.
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Tang R, Yang S, Narsing Rao MP, Xie CJ, Han S, Yang QE, Rensing C, Liu GH, Yuan Y, Zhou SG. Three Fe(III)-reducing and nitrogen-fixing bacteria, Anaeromyxobacter terrae sp. nov., Anaeromyxobacter oryzisoli sp. nov. and Anaeromyxobacter soli sp. nov., isolated from paddy soil. Int J Syst Evol Microbiol 2024; 74. [PMID: 38323900 DOI: 10.1099/ijsem.0.006268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2024] Open
Abstract
Three microaerophilic bacterial strains, designated SG22T, SG63T and SG29T were isolated from paddy soils in PR China. Cells of these strains were Gram-staining-negative and long rod-shaped. SG22T, SG63T and SG29T showed the highest 16S rRNA gene sequence similarities with the members of the genus Anaeromyxobacter. The results of phylogenetic and phylogenomic analysis also indicated that these strains clustered with members of the genus Anaeromyxobacter. The main respiratory menaquinone of SG22T, SG63T and SG29T was MK-8 and the major fatty acids were iso-C15 : 0, iso-C17 : 0 and C16 : 0. SG22T, SG29T and SG63T not only possessed iron reduction ability but also harboured genes (nifHDK) encoding nitrogenase. The genomic DNA G+C contents of SG22T, SG63T and SG29T ranged from 73.3 to 73.5 %. The average nucleotide identity (ANI) and digital DNA-DNA hybridisation (dDDH) values between SG22T, SG63T and SG29T and the closely related species of the genus Anaeromyxobacter were lower than the cut-off values (dDDH 70 % and ANI 95-96 %) for prokaryotic species delineation. On the basis of these results, strains SG22T, SG63T and SG29T represent three novel species within the genus Anaeromyxobacter, for which the names Anaeromyxobacter terrae sp. nov., Anaeromyxobacter oryzisoli sp. nov. and Anaeromyxobacter soli sp. nov., are proposed. The type strains are SG22T (= GDMCC 1.3185T = JCM 35581T), SG63T (= GDMCC 1.2914T = JCM 35124T) and SG29T (= GDMCC 1.2911T = JCM 35123T).
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Affiliation(s)
- Rong Tang
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, PR China
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
| | - Shang Yang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
| | - Manik Prabhu Narsing Rao
- Instituto de Ciencias Aplicadas, Facultad de Ingeniería, Universidad Autónoma de Chile, Sede Talca, Talca 3460000, Chile
| | - Cheng-Jie Xie
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
| | - Shuang Han
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
| | - Qiu-E Yang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
| | - Christopher Rensing
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
| | - Guo-Hong Liu
- Agricultural Bio-resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, Fujian 350003, PR China
| | - Yong Yuan
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, PR China
| | - Shun-Gui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, PR China
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Ikeda T, Ogawa T, Aono T. Dethiobiotin uptake and utilization by bacteria possessing bioYB operon. Res Microbiol 2023; 174:104131. [PMID: 37640259 DOI: 10.1016/j.resmic.2023.104131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 08/21/2023] [Accepted: 08/23/2023] [Indexed: 08/31/2023]
Abstract
Biotin is an essential vitamin for all organisms. Some bacteria cannot synthesize biotin and live by acquiring biotin from the environment. Bacterial biotin transporters (BioY) are classified into three mechanistic types. The first forms the BioMNY complex with ATPase (BioM) and transmembrane protein (BioN). The second relies on a promiscuous energy coupling module. The third functions independently. One-third of bioY genes spread in bacteria cluster with bioM and bioN on the genomes, and the rest does not. Interestingly, some bacteria have the bioY gene clustering with bioB gene, which encodes biotin synthase, an enzyme that converts dethiobiotin to biotin, on their genome. This bioY-bioB cluster is observed even though these bacteria cannot synthesize biotin. Azorhizobium caulinodans ORS571, a rhizobium of tropical legume Sesbania rostrata, is one of such bacteria. In this study using this bacterium, we demonstrated that the BioY linked to BioB could transport not only biotin but also dethiobiotin, and the combination of BioY and BioB contributed to the growth of A. caulinodans ORS571 in a biotin-deficient but dethiobiotin-sufficient environment. We propose that such environment universally exists in the natural world, and the identification of such environment will be a new subject in the field of microbial ecology.
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Affiliation(s)
- Tomoki Ikeda
- Biotechnology Research Center, The University of Tokyo. 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Tetsuhiro Ogawa
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo. 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan; Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
| | - Toshihiro Aono
- Biotechnology Research Center, The University of Tokyo. 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan.
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Xie CJ, Yang S, Tang R, Han S, Liu GH, Zhou SG. Sulfurospirillum oryzae sp. nov., A Novel Nitrogen-Fixing Bacterium Isolated from Paddy Soil. Curr Microbiol 2023; 80:207. [PMID: 37165205 DOI: 10.1007/s00284-023-03312-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 04/24/2023] [Indexed: 05/12/2023]
Abstract
An anaerobic, Gram-staining-negative, rod shaped, nitrogen-fixing strain designed SG202T, was isolated from paddy soil collected from Fujian Province in China. Strain SG202T showed the highest 16S rRNA gene sequence similarity with the type strain Sulfurospirillum multivorans DSM 12446T (98.5%). Phylogenetic trees based on 16S rRNA gene sequences and conserved core genes from genomes indicated that strain SG202T branched with members of the genus Sulfurospirillum. Growth was observed at 25-37 °C (optimum 30 °C), pH 6.0-10.5 (optimum 7.5), and 0-0.6% (w/v) NaCl (optimum 0.2%). Strain SG202T contained MK-6 as the menaquinone and C16:1ω7c (40.6%), C16:0 (33.3%), C18:1ω7c (13.6%) and C14:0 (9.0%) as the major fatty acids. The genomic DNA G+C content was 39.0%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain SG202T and its closely related species S. multivorans DSM 12446T, Sulfurospirillum halorespirans DSM 13726T, Sulfurospirillum arsenophilum DSM 10659T and Sulfurospirillum diekertiae ACSDCET were 81.3, 81.5, 84.4, 82.2% and 24.5, 24.5, 27.9, 25.2%, respectively. All these values were lower than the recommended species delineation thresholds of ANI (95-96%) and dDDH (70%). Strain SG202T possessed core genes (nifHDK) of nitrogen fixation, and nitrogenase activities (3470.45 μmol C2H4 g-1 protein h-1) was examined using the acetylene reduction assay. Based on the observed physiological properties, chemotaxonomic characteristics and genome analysis, strain SG202T is recognized as a novel species of the genus Sulfurospirillum, for which the name Sulfurospirillum oryzae sp. nov. is proposed. The type strain is SG202T (= GDMCC 1.3379T= JCM 35596T).
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Affiliation(s)
- Cheng-Jie Xie
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, Fujian Province, People's Republic of China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou City, 510642, Guangdong Province, People's Republic of China
| | - Shang Yang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, Fujian Province, People's Republic of China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou City, 510642, Guangdong Province, People's Republic of China
| | - Rong Tang
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Guangdong Province, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou City, 510006, People's Republic of China
| | - Shuang Han
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, Fujian Province, People's Republic of China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou City, 510642, Guangdong Province, People's Republic of China
| | - Guo-Hong Liu
- Agricultural Bio-resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou City, 350003, Fujian Province, People's Republic of China.
| | - Shun-Gui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, Fujian Province, People's Republic of China.
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou City, 510642, Guangdong Province, People's Republic of China.
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Yang S, Tang R, Han S, Xie CJ, Liu GH, Zhou SG. A novel strictly anaerobic sulfate-reducing diazotrophic bacterium Fundidesulfovibrio terrae sp. nov., isolated from paddy soil. Int J Syst Evol Microbiol 2023; 73. [PMID: 37185059 DOI: 10.1099/ijsem.0.005880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023] Open
Abstract
A strictly anaerobic sulfate-reducing strain, designated SG127T, was isolated from paddy soil. SG127T showed the highest 16S rRNA gene sequence similarity to the type strain of Fundidesulfovibrio magnetotacticus (98.2 %). A phylogenetic tree based on 16S rRNA gene sequences indicated that SG127T clustered with members of the genus Fundidesulfovibrio. Growth of SG127T was observed at 20-37 °C (optimum, 30 °C), pH 5.5-9.0 (optimum, 7.0-8.0) and with 0-0.2 % (w/v) NaCl (optimally without NaCl). SG127T contained MK-7 as the only menaquinone and anteiso-C15 : 0, anteiso-C17 : 1ω9c, C18 : 0, iso-C14 : 0, iso-C15 : 0, iso-C16:0, iso-C16 : 1H, iso-C18 : 1H and summed feature nine as the major fatty acids. The genomic DNA G+C content of SG127T was 64.6 %. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between SG127T and the closely related Fundidesulfovibrio magnetotacticus were 78.5% and 23.2 %, respectively, which were lower than the cut-off values (ANI 95-96% and dDDH 70 %) for prokaryotic species delineation. SG127T had desulfoviridin, possessed nitrogen fixation genes (nifHDK) and actively fixed nitrogen according to the acetylene reduction assay. On the basis of these results, strain SG127T represents a novel species of the genus Fundidesulfovibrio, for which the name Fundidesulfovibrio terrae sp. nov. is proposed. The type strain is SG127T (= GDMCC 1.3137T = JCM 35589T).
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Affiliation(s)
- Shang Yang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, PR China
| | - Rong Tang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, PR China
| | - Shuang Han
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, PR China
| | - Cheng-Jie Xie
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, PR China
| | - Guo-Hong Liu
- Agricultural Bio-resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou City, 350003, PR China
| | - Shun-Gui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, PR China
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Liu Y, Liu X, Dong X, Yin Z, Xie Z, Luo Y. Systematic Analysis of Lysine Acetylation Reveals Diverse Functions in Azorhizobium caulinodans Strain ORS571. Microbiol Spectr 2023; 11:e0353922. [PMID: 36475778 PMCID: PMC9927263 DOI: 10.1128/spectrum.03539-22] [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: 09/04/2022] [Accepted: 11/11/2022] [Indexed: 12/13/2022] Open
Abstract
Protein acetylation can quickly modify the physiology of bacteria to respond to changes in environmental or nutritional conditions, but little information on these modifications is available in rhizobia. In this study, we report the lysine acetylome of Azorhizobium caulinodans strain ORS571, a model rhizobium isolated from stem nodules of the tropical legume Sesbania rostrata that is capable of fixing nitrogen in the free-living state and during symbiosis. Antibody enrichment and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis were used to characterize the acetylome. There are 2,302 acetylation sites from 982 proteins, accounting for 20.8% of the total proteins. Analysis of the acetylated motifs showed the preferences for the amino acid residues around acetylated lysines. The response regulator CheY1, previously characterized to be involved in chemotaxis in strain ORS571, was identified as an acetylated protein, and a mutation of the acetylated site of CheY1 significantly impaired the strain's motility. In addition, a Zn+-dependent deacetylase (AZC_0414) was characterized, and the construction of a deletion mutant strain showed that it played a role in chemotaxis. Our study provides the first global analysis of lysine acetylation in ORS571, suggesting that acetylation plays a role in various physiological processes. In addition, we demonstrate its involvement in the chemotaxis process. The acetylome of ORS571 provides insights to investigate the regulation mechanism of rhizobial physiology. IMPORTANCE Acetylation is an important modification that regulates protein function and has been found to regulate physiological processes in various bacteria. The physiology of rhizobium A. caulinodans ORS571 is regulated by multiple mechanisms both when free living and in symbiosis with the host; however, the regulatory role of acetylation is not yet known. Here, we took an acetylome-wide approach to identify acetylated proteins in A. caulinodans ORS571 and performed clustering analyses. Acetylation of chemotaxis proteins was preliminarily investigated, and the upstream acetylation-regulating enzyme involved in chemotaxis was characterized. These findings provide new insights to explore the physiological mechanisms of rhizobia.
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Affiliation(s)
- Yanan Liu
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiaolin Liu
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Xiaoyan Dong
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Zhiqiu Yin
- National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment of Shandong Agricultural University, Taian, China
| | - Zhihong Xie
- National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment of Shandong Agricultural University, Taian, China
| | - Yongming Luo
- CAS Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
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Yang S, Tang R, Xie CJ, Han S, Rensing C, Liu GH, Zhou SG. A novel sulfate-reducing and nitrogen-fixing bacterium Fundidesulfovibrio soli sp. nov., isolated from paddy soils. Arch Microbiol 2023; 205:80. [PMID: 36735086 DOI: 10.1007/s00203-023-03412-3] [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: 12/13/2022] [Accepted: 01/10/2023] [Indexed: 02/04/2023]
Abstract
A strictly anaerobic sulfate-reducing strain, designated SG60T, was isolated from paddy soil collected in Fujian Province, China. Growth of strain SG60T was observed at 20-37 °C, pH 5.5-10.0 and 0-0.7% (w/v) NaCl. Strain SG60T showed the highest 16S rRNA sequence similarities to the type strains of Fundidesulfovibrio magnetotacticus FSS-1T (97.2%) and Fundidesulfovibrio putealis DSM 16056T (96.4%). Phylogenetic trees based on the16S rRNA sequence and genome-based phylogenomic tree constructed using 120 core genes showed that strain SG60T clustered with members of the genus Fundidesulfovibrio. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain SG60T and the most closely related type strain F. magnetotacticus were 78.2% and 21.6%, respectively. Strain SG60T contained MK-7 as the main respiratory quinone and anteiso-C15:0, anteiso-C17:1 ω9c, iso-C16:0 and iso-C16:1 H as the major fatty acids. Strain SG60T produced desulfoviridin and possessed genes (nifHDK) encoding functions involved in nitrogen fixation. The genomic DNA G + C content was 65.5%. Based on the observed physiological properties, chemotaxonomic characteristics and ANI and dDDH values, strain SG60T represents a novel species of the genus Fundidesulfovibrio, for which the name Fundidesulfovibrio soli sp. nov. is proposed. The type strain is SG60T (= GDMCC 1.3310T = JCM 35676T).
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Affiliation(s)
- Shang Yang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, Fujian Province, People's Republic of China
| | - Rong Tang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, Fujian Province, People's Republic of China
| | - Cheng-Jie Xie
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, Fujian Province, People's Republic of China
| | - Shuang Han
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, Fujian Province, People's Republic of China
| | - Christopher Rensing
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, Fujian Province, People's Republic of China
| | - Guo-Hong Liu
- Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou City, 350003, Fujian Province, People's Republic of China.
| | - Shun-Gui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, Fujian Province, People's Republic of China.
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A novel nitrogen-fixing bacterium, Propionivibrio soli sp. nov. isolated from paddy soil. Arch Microbiol 2023; 205:68. [PMID: 36662302 DOI: 10.1007/s00203-023-03413-2] [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: 11/14/2022] [Revised: 01/04/2023] [Accepted: 01/10/2023] [Indexed: 01/21/2023]
Abstract
A facultative anaerobic nitrogen-fixing bacterium, designated SG131T, was isolated from paddy soil. Strain SG131T showed high 16S rRNA gene sequence similarities with type strains Propionivibrio limicola DSM 6832T (96.9%), Propionivibrio pelophilus asp 66T (96.0%) and Propionivibrio dicarboxylicus DSM 5885T (95.7%). The phylogenetic trees (based on 16S rRNA gene sequences and 120 conserved genes from genomes, respectively) indicated that strain SG131T clustered with members of the genus Propionivibrio. Growth of strain SG131T was observed at 25-40 °C, pH 5.5-10.5 and 0-0.5% (w/v) NaCl. The quinone was Q-7, and the main fatty acids were C16:1 ω6c and/or C16:1 ω7c (25.9%), C16:0 (23.3%), C17:0-cyclo (11.7%), C12:0 (6.0%) and C17:0 (5.9%). The genomic DNA G + C content of strain SG131T was 60.3%. The average nucleotide identity (ANI) values between strain SG131T and its most closely related species P. limicola DSM 6832T, P. pelophilus DSM 12018T and P. dicarboxylicus DSM 5885T were 74.4%, 74.9% and 75.6%, respectively. The digital DNA-DNA hybridization (dDDH) values between strain SG131T and its most closely related species P. limicola DSM 6832T, P. pelophilus DSM 12018T and P. dicarboxylicus DSM 5885T were 19.9%, 20.6% and 20.5%, respectively. All these values were lower than the recommended species delineation thresholds of ANI (95-96%) and dDDH (70%). Strain SG131T possessed core genes (nifHDK) of nitrogen fixation and was confirmed its nitrogen-fixing ability by the ARA method. According to the above-described analysis, strain SG131T represents a novel species of the genus Propionivibrio, for which the name Propionivibrio soli sp. nov. is proposed. The type strain is SG131T (= GDMCC 1.3313T = JCM 35595T).
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Yang S, Tang R, Han S, Xie CJ, Narsing Rao MP, Liu GH, Zhou SG. Fundidesulfovibrio agrisoli sp. nov., A Nitrogen-Fixing Bacterium Isolated from Rice Field. Curr Microbiol 2023; 80:68. [PMID: 36609736 DOI: 10.1007/s00284-022-03140-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 12/02/2022] [Indexed: 01/09/2023]
Abstract
A strictly anaerobic nitrogen-fixing strain, designated SG106T, was isolated from rice field. The 16S rRNA gene sequence analysis showed that strain SG106T was closely related to the type strain of Fundidesulfovibrio magnetotacticus (97.3%). In phylogenetic (based on 16S rRNA gene sequences) and phylogenomic (constructed using a concatenated alignment of 117 conserved bacterial single-copy genes with GTDB-Tk) trees, strain SG106T clustered with members of the genus Fundidesulfovibrio. Strain SG106T grew at 20-40 °C and 0-0.4% (w/v) NaCl. Desulfoviridin was found in the strain SG106T. The genomic DNA G + C content of strain SG106T was 66.0%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain SG106T and the closely related F. magnetotacticus were 78.4% and 21.7%, respectively. Genome analysis showed that strain SG106T encodes genes for nitrogen fixation (nifHDK). Acetylene reduction experiments showed that the nitrogenase activity of strain SG106T could reach 224.7 μmol C2H4 g-1 protein h-1. Based on the above results, strain SG106T represents a novel species of the genus Fundidesulfovibrio, for which the name Fundidesulfovibrio agrisoli sp. nov. is proposed. The type strain is SG106T (= GDMCC 1.3136T = JCM 35588T).
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Affiliation(s)
- Shang Yang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, Fujian Province, 350002, People's Republic of China
| | - Rong Tang
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou, 510006, People's Republic of China
| | - Shuang Han
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, Fujian Province, 350002, People's Republic of China
| | - Cheng-Jie Xie
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, Fujian Province, 350002, People's Republic of China
| | - Manik Prabhu Narsing Rao
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, Fujian Province, 350002, People's Republic of China
| | - Guo-Hong Liu
- Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou City, Fujian Province, 350003, People's Republic of China.
| | - Shun-Gui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, Fujian Province, 350002, People's Republic of China.
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10
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Yang S, Liu GH, Tang R, Han S, Xie CJ, Zhou SG. Description of two nitrogen-fixing bacteria, Geomonas fuzhouensis sp. nov. and Geomonas agri sp. nov., isolated from paddy soils. Antonie Van Leeuwenhoek 2022; 115:435-444. [PMID: 35094155 DOI: 10.1007/s10482-021-01704-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 12/21/2021] [Indexed: 12/16/2022]
Abstract
Two strictly anaerobic nitrogen-fixing strains, designated RG17T and RG53T, were isolated from paddy soils in China. Strains RG17T and RG53T showed the highest 16S rRNA gene sequence similarities to the type strain Geomonas paludis (97.9-98.4%). Phylogenetic tree based on 16S rRNA gene sequences showed that two strains clustered with members of the genus Geomonas. Growth of strain RG17T was observed at 20-42 °C, pH 5.5-8.5 and 0-0.3% (w/v) NaCl while strain RG53T growth was observed at 20-42 °C, pH 5.5-9.5 and 0-0.7% (w/v) NaCl. Strains RG17T and RG53T contained MK-8 as main menaquinone and C15:1 ω6c, iso-C15:0, and Summed Feature 3 as the major fatty acids. The genomic DNA G + C content of strains RG17T and RG53T were 61.6 and 60.7%, respectively. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between the isolated strains and the closely related Geomonas species were lower than the cut-off value (dDDH 70% and ANI 95-96%) for prokaryotic species delineation. Both strains possessed nif genes nifHDK and nitrogenase activities. Based on the above results, the two strains represent two novel species of the genus Geomonas, for which the names Geomonas fuzhouensis sp. nov. and Geomonas agri sp. nov., are proposed. The type strains are RG17T (= GDMCC 1.2687T = KTCC 25332T) and RG53T (= GDMCC 1.2630T = KCTC 25331T), respectively.
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Affiliation(s)
- Shang Yang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, Fujian Province, People's Republic of China.,Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou City, 350003, Fujian Province, People's Republic of China
| | - Guo-Hong Liu
- Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou City, 350003, Fujian Province, People's Republic of China
| | - Rong Tang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, Fujian Province, People's Republic of China.,Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou City, 350003, Fujian Province, People's Republic of China
| | - Shuang Han
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, Fujian Province, People's Republic of China.,Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou City, 350003, Fujian Province, People's Republic of China
| | - Cheng-Jie Xie
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, Fujian Province, People's Republic of China.,Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou City, 350003, Fujian Province, People's Republic of China
| | - Shun-Gui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou City, 350002, Fujian Province, People's Republic of China.
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Liu GH, Yang S, Tang R, Xie CJ, Zhou SG. Genome Analysis and Description of Three Novel Diazotrophs Geomonas Species Isolated From Paddy Soils. Front Microbiol 2022; 12:801462. [PMID: 35197944 PMCID: PMC8859169 DOI: 10.3389/fmicb.2021.801462] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 12/14/2021] [Indexed: 12/05/2022] Open
Abstract
Five strictly anaerobic strains, designated RG2T, RG3, RG10T, RF4T, and RG29, were isolated from paddy soils in China. Strains RG2T, RF4T, RG10T, RG3, and RG29 grew at temperatures ranging 5–42°C and pH ranging 5.5–8.5. Strains RG2T, RF4T, RG3, and RG29 could tolerate NaCl up to 0–0.7% (w/v) while strain RG10T could tolerate NaCl up to 0–0.8% (w/v). The isolated strains showed the highest 16S rRNA gene sequence similarities to the type strains of Geomonas terrae Red111T and Geomonas paludis Red736T. In phylogenetic (based on 16S rRNA gene sequence) and phylogenomic trees, strains clustered with the members of the genus Geomonas. Menaquinone-8 was the predominant quinone present in all strains. The major fatty acid profiles of all strains were C15:1 ω6c, C16:0, iso-C15:0, and Summed Feature 3. The digital DNA–DNA hybridization (dDDH) and average nucleotide identity (ANI) values between the isolated strains and the closely related Geomonas species were lower than the cutoff value (ANI 95–96% and dDDH 70%) for prokaryotic species delineation. Based on physiological, biochemical, and chemotaxonomic properties, strains RG2T, RG10T, and RF4T could easily be differentiated with the members of the genus Geomonas. Additionally, all the isolated strains possessed nifHDK clusters and catalytic compartments of nitrogenase. Based on the above results, the isolated five strains represent three novel species of the genus Geomonas, for which the names Geomonas oryzisoli sp. nov., Geomonas subterranea sp. nov., and Geomonas nitrogeniifigens sp. nov. are proposed. The type strains are RG10T (= GDMCC1.2537T = KCTC 26318T), RG2T (= GDMCC1.2536T = KCTC 25317T), and RF4T (= GDMCC 1.2547T = KCTC 25316T).
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Affiliation(s)
- Guo-Hong Liu
- Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, China
| | - Shang Yang
- Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, China
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Rong Tang
- Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, China
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Cheng-Jie Xie
- Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, China
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Shun-Gui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
- *Correspondence: Shun-Gui Zhou,
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12
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Diazotrophic Anaeromyxobacter Isolates from Soils. Appl Environ Microbiol 2020; 86:AEM.00956-20. [PMID: 32532868 DOI: 10.1128/aem.00956-20] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/04/2020] [Indexed: 11/20/2022] Open
Abstract
Biological nitrogen fixation is an essential reaction in a major pathway for supplying nitrogen to terrestrial environments. Previous culture-independent analyses based on soil DNA/RNA/protein sequencing could globally detect the nitrogenase genes/proteins of Anaeromyxobacter (in the class Deltaproteobacteria), commonly distributed in soil environments and predominant in paddy soils; this suggests the importance of Anaeromyxobacter in nitrogen fixation in soil environments. However, direct experimental evidence is lacking; there has been no research on the genetic background and ability of Anaeromyxobacter to fix nitrogen. Therefore, we verified the diazotrophy of Anaeromyxobacter based on both genomic and culture-dependent analyses using Anaeromyxobacter sp. strains PSR-1 and Red267 isolated from soils. Based on the comparison of nif gene clusters, strains PSR-1 and Red267 as well as strains Fw109-5, K, and diazotrophic Geobacter and Pelobacter in the class Deltaproteobacteria contain the minimum set of genes for nitrogenase (nifBHDKEN). These results imply that Anaeromyxobacter species have the ability to fix nitrogen. In fact, Anaeromyxobacter PSR-1 and Red267 exhibited N2-dependent growth and acetylene reduction activity (ARA) in vitro Transcriptional activity of the nif gene was also detected when both strains were cultured with N2 gas as a sole nitrogen source, indicating that Anaeromyxobacter can fix and assimilate N2 gas by nitrogenase. In addition, PSR-1- or Red267-inoculated soil showed ARA activity and the growth of the inoculated strains on the basis of RNA-based analysis, demonstrating that Anaeromyxobacter can fix nitrogen in the paddy soil environment. Our study provides novel insights into the pivotal environmental function, i.e., nitrogen fixation, of Anaeromyxobacter, which is a common soil bacterium.IMPORTANCE Anaeromyxobacter is globally distributed in soil environments, especially predominant in paddy soils. Current studies based on environmental DNA/RNA analyses frequently detect gene fragments encoding nitrogenase of Anaeromyxobacter from various soil environments. Although the importance of Anaeromyxobacter as a diazotroph in nature has been suggested by culture-independent studies, there has been no solid evidence and validation from genomic and culture-based analyses that Anaeromyxobacter fixes nitrogen. This study demonstrates that Anaeromyxobacter harboring nitrogenase genes exhibits diazotrophic ability; moreover, N2-dependent growth was demonstrated in vitro and in the soil environment. Our findings indicate that nitrogen fixation is important for Anaeromyxobacter to survive under nitrogen-deficient environments and provide a novel insight into the environmental function of Anaeromyxobacter, which is a common bacterium in soils.
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CheY1 and CheY2 of Azorhizobium caulinodans ORS571 Regulate Chemotaxis and Competitive Colonization with the Host Plant. Appl Environ Microbiol 2020; 86:AEM.00599-20. [PMID: 32471918 DOI: 10.1128/aem.00599-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 05/21/2020] [Indexed: 02/06/2023] Open
Abstract
The genome of Azorhizobium caulinodans ORS571 encodes two chemotaxis response regulators: CheY1 and CheY2. cheY1 is located in a chemotaxis cluster (cheAWY1BR), while cheY2 is located 37 kb upstream of the cheAWY1BR cluster. To determine the contributions of CheY1 and CheY2, we compared the wild type (WT) and mutants in the free-living state and in symbiosis with the host Sesbania rostrata Swim plate tests and capillary assays revealed that both CheY1 and CheY2 play roles in chemotaxis, with CheY2 having a more prominent role than CheY1. In an analysis of the swimming paths of free-swimming cells, the ΔcheY1 mutant exhibited decreased frequency of direction reversal, whereas the ΔcheY2 mutant appeared to change direction much more frequently than the WT. Exopolysaccharide (EPS) production in the ΔcheY1 and ΔcheY2 mutants was lower than that in the WT, but the ΔcheY2 mutant had more obvious EPS defects that were similar to those of the ΔcheY1 ΔcheY2 and Δeps1 mutants. During symbiosis, the levels of competitiveness for root colonization and nodule occupation of ΔcheY1 and ΔcheY2 mutants were impaired compared to those of the WT. Moreover, the competitive colonization ability of the ΔcheY2 mutant was severely impaired compared to that of the ΔcheY1 mutant. Taken together, the ΔcheY2 phenotypes are more severe than the ΔcheY1 phenotype in free-living and symbiotic states, and that of the double mutant resembles the ΔcheY2 single-mutant phenotype. These defects of ΔcheY1 and ΔcheY2 mutants were restored to the WT phenotype by complementation. These results suggest that there are different regulatory mechanisms of CheY1 and CheY2 and that CheY2 is a key chemotaxis regulator under free-living and symbiosis conditions.IMPORTANCE Azorhizobium caulinodans ORS571 is a motile soil bacterium that has the dual capacity to fix nitrogen both under free-living conditions and in symbiosis with Sesbania rostrata, forming nitrogen-fixing root and stem nodules. Bacterial chemotaxis to chemoattractants derived from host roots promotes infection and subsequent nodule formation by directing rhizobia to appropriate sites of infection. In this work, we identified and demonstrated that CheY2, a chemotactic response regulator encoded by a gene outside the chemotaxis cluster, is required for chemotaxis and multiple other cell phenotypes. CheY1, encoded by a gene in the chemotaxis cluster, also plays a role in chemotaxis. Two response regulators mediate bacterial chemotaxis and motility in different ways. This work extends the understanding of the role of multiple response regulators in Gram-negative bacteria.
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Liu W, Li Y, Bai X, Wu H, Bian L, Hu X. LuxR-Type Regulator AclR1 of Azorhizobium caulinodans Regulates Cyclic di-GMP and Numerous Phenotypes in Free-Living and Symbiotic States. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:528-538. [PMID: 31789101 DOI: 10.1094/mpmi-10-19-0306-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
LuxR-type regulators play important roles in transcriptional regulation in bacteria and control various biological processes. A genome sequence analysis showed the existence of seven LuxR-type regulators in Azorhizobium caulinodans ORS571, an important nitrogen-fixing bacterium in both its free-living state and in symbiosis with its host, Sesbania rostrata. However, the functional mechanisms of these regulators remain unclear. In this study, we identified a LuxR-type regulator that contains a cheY-homologous receiver (REC) domain in its N terminus and designated it AclR1. Interestingly, phylogenetic analysis revealed that AclR1 exhibited relatively close evolutionary relationships with MalT/GerE/FixJ/NarL family proteins. Functional analysis of an aclR1 deletion mutant (ΔaclR1) in the free-living state showed that AclR1 positively regulated cell motility and flocculation but negatively regulated exopolysaccharide production, biofilm formation, and second messenger cyclic diguanylate (c-di-GMP)-related gene expression. In the symbiotic state, the ΔaclR1 mutant was defective in competitive colonization and nodulation on host plants. These results suggested that AclR1 could provide bacteria with the ability to compete effectively for symbiotic nodulation. Overall, our results show that the REC-LuxR-type regulator AclR1 regulates numerous phenotypes both in the free-living state and during host plant symbiosis.
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Affiliation(s)
- Wei Liu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Yan Li
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Xue Bai
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- College of Life Sciences, Yantai University, Yantai, China
| | - Haiguang Wu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- College of Life Sciences, Yantai University, Yantai, China
| | - Lanxing Bian
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- College of Life Sciences, Yantai University, Yantai, China
| | - Xiaoke Hu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
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15
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Sun Y, Liu Y, Liu X, Dang X, Dong X, Xie Z. Azorhizobium caulinodans c-di-GMP phosphodiesterase Chp1 involved in motility, EPS production, and nodulation of the host plant. Appl Microbiol Biotechnol 2020; 104:2715-2729. [PMID: 32002604 DOI: 10.1007/s00253-020-10404-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 01/06/2020] [Accepted: 01/23/2020] [Indexed: 12/18/2022]
Abstract
Establishment of the rhizobia-legume symbiosis is usually accompanied by hydrogen peroxide (H2O2) production by the legume host at the site of infection, a process detrimental to rhizobia. In Azorhizobium caulinodans ORS571, deletion of chp1, a gene encoding c-di-GMP phosphodiesterase, led to increased resistance against H2O2 and to elevated nodulation efficiency on its legume host Sesbania rostrata. Three domains were identified in the Chp1: a PAS domain, a degenerate GGDEF domain, and an EAL domain. An in vitro enzymatic activity assay showed that the degenerate GGDEF domain of Chp1 did not have diguanylate cyclase activity. The phosphodiesterase activity of Chp1 was attributed to its EAL domain which could hydrolyse c-di-GMP into pGpG. The PAS domain functioned as a regulatory domain by sensing oxygen. Deletion of Chp1 resulted in increased intracellular c-di-GMP level, decreased motility, increased aggregation, and increased EPS (extracellular polysaccharide) production. H2O2-sensitivity assay showed that increased EPS production could provide ORS571 with resistance against H2O2. Thus, the elevated nodulation efficiency of the ∆chp1 mutant could be correlated with a protective role of EPS in the nodulation process. These data suggest that c-di-GMP may modulate the A. caulinodans-S. rostrata nodulation process by regulating the production of EPS which could protect rhizobia against H2O2.
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Affiliation(s)
- Yu Sun
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, People's Republic of China
| | - Yanan Liu
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Xiaolin Liu
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Xiaoxiao Dang
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Xiaoyan Dong
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- Center for Ocean Mag-Science, Chinese Academy of Sciences, Qingdao, People's Republic of China
| | - Zhihong Xie
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China.
- Center for Ocean Mag-Science, Chinese Academy of Sciences, Qingdao, People's Republic of China.
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Liu X, Xie Z. Inactivation of the Phosphatase CheZ Alters Cell-Surface Properties of Azorhizobium caulinodans ORS571 and Symbiotic Association with Sesbania rostrata. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:1547-1556. [PMID: 31287368 DOI: 10.1094/mpmi-05-19-0143-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Azorhizobium caulinodans can form root and stem nodules with the host plant Sesbania rostrata. The role of the CheZ phosphatase in the A. caulinodans chemotaxis pathway was previously explored using the nonchemotactic cheZ mutant strain (AC601). This mutant displayed stronger attachment to the root surface, enhancing early colonization; however, this did not result in increased nodulation efficiency. In this study, we further investigated the role of CheZ in the interaction between strain ORS571 and the roots of its host plant. By tracking long-term colonization dynamic of cheZ mutant marked with LacZ, we found a decrease of colonization of the cheZ mutant during this process. Furthermore, the cheZ mutant could not spread on the root surface freely and was gradually outcompeted by the wild type in original colonization sites. Quantitative reverse-transcription PCR analyses showed that exp genes encoding exopolysaccharides synthesis, including oac3, were highly expressed in the cheZ mutant. Construction of a strain carrying a deletion of both cheZ and oac3 resulted in a mutant strain defective in the colonization process to the same extent as found with the oac3 single-mutant strain. This result suggested that the enhanced colonization of the cheZ mutant may be achieved through regulating the formation of exopolysaccharides. This shows the importance of the chemotactic proteins in the interaction between rhizobia and host plants, and expands our understanding of the symbiosis interaction between rhizobium and host plant.
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Affiliation(s)
- Xiaolin Liu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
- Center for Ocean Mag-Science, Chinese Academy of Sciences, Qingdao, People's Republic of China
| | - Zhihong Xie
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- Center for Ocean Mag-Science, Chinese Academy of Sciences, Qingdao, People's Republic of China
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17
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Matsuoka JI, Ishizuna F, Ogawa T, Hidaka M, Siarot L, Aono T. Localization of the reb operon expression is inconsistent with that of the R-body production in the stem nodules formed by Azorhizobium caulinodans mutants having a deletion of praR. J GEN APPL MICROBIOL 2019; 65:209-213. [PMID: 30726794 DOI: 10.2323/jgam.2018.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Azorhizobium caulinodans, a kind of rhizobia, has a reb operon encoding pathogenic R-body components, whose expression is usually repressed by a transcription factor PraR. Mutation on praR induced a high expression of reb operon and the formation of aberrant nodules, in which both morphologically normal and shrunken host cells were observed. Histochemical GUS analyses of praR mutant expressing reb operon-uidA fusion revealed that the bacterial cells within the normal host cells highly expressed the reb operon, but rarely produced R-bodies. On the other hand, the bacterial cells within the shrunken host cells frequently produced R-bodies but rarely expressed the reb operon. This suggests that R-body production is not only regulated at the transcriptional level, but by other regulatory mechanisms as well.
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Affiliation(s)
| | - Fumiko Ishizuna
- Faculty of Contemporary Human Life Science, Tokyo Kasei Gakuin University
| | - Tetsuhiro Ogawa
- Graduate School of Agricultural and Life Sciences, The University of Tokyo.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo
| | - Makoto Hidaka
- Graduate School of Agricultural and Life Sciences, The University of Tokyo.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo
| | - Lowela Siarot
- Biotechnology Research Center, The University of Tokyo
| | - Toshihiro Aono
- Biotechnology Research Center, The University of Tokyo.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo
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18
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Liu X, Xie Z, Wang Y, Sun Y, Dang X, Sun H. A Dual Role of Amino Acids from Sesbania rostrata Seed Exudates in the Chemotaxis Response of Azorhizobium caulinodans ORS571. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:1134-1147. [PMID: 30920344 DOI: 10.1094/mpmi-03-19-0059-r] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Azorhizobium caulinodans ORS571 can induce nodule formation on the roots and the stems of its host legume, Sesbania rostrata. Plant exudates are essential in the dialogue between microbes and their host plant and, in particular, amino acids can play an important role in the chemotactic response of bacteria. Histidine, arginine, and aspartate, which are the three most abundant amino acids present in S. rostrata seed exudates, behave as chemoattractants toward A. caulinodans. A position-specific-iterated BLAST analysis of the methyl-accepting chemotaxis proteins (MCPs) (chemoreceptors) in the genome of A. caulinodans was performed. Among the 43 MCP homologs, two MCPs harboring a dCache domain were selected as possible cognate amino acid MCPs. After analysis of relative gene expression levels and construction of a gene-deleted mutant strain, one of them, AZC_0821 designed as TlpH, was confirmed to be responsible for the chemotactic response to the three amino acids. In addition, it was found that these three amino acids can also influence chemotaxis of A. caulinodans independently of the chemosensory receptors, by being involved in the increase of the expression level of several che and fla genes involved in the chemotaxis pathway and flagella synthesis. Thus, the contribution of amino acids present in seed exudates is directly related to the role as chemoattractants and indirectly related to the role in the regulation of expression of key genes involved in chemotaxis and motility. This "dual role" is likely to influence the formation of biofilms by A. caulinodans and the host root colonization properties of this bacterium.
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Affiliation(s)
- Xiaolin Liu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Zhihong Xie
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
| | - Yixuan Wang
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Yu Sun
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Xiaoxiao Dang
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Haishuan Sun
- Shandong Huibang Bohai Agriculture Development Limited Company, Dongying, People's Republic of China
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Sun Y, Xie Z, Sui F, Liu X, Cheng W. Identification of Cbp1, a c-di-GMP Binding Chemoreceptor in Azorhizobium caulinodans ORS571 Involved in Chemotaxis and Nodulation of the Host Plant. Front Microbiol 2019; 10:638. [PMID: 31001223 PMCID: PMC6454048 DOI: 10.3389/fmicb.2019.00638] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 03/13/2019] [Indexed: 01/10/2023] Open
Abstract
Cbp1, a chemoreceptor containing a PilZ domain was identified in Azorhizobium caulinodans ORS571, a nitrogen-fixing free-living soil bacterium that induces nodule formation in both the roots and stems of the host legume Sesbania rostrata. Chemoreceptors are responsible for sensing signals in the chemotaxis pathway, which guides motile bacteria to beneficial niches and plays an important role in the establishment of rhizobia-legume symbiosis. PilZ domain proteins are known to bind the second messenger c-di-GMP, an important regulator of motility, biofilm formation and virulence. Cbp1 was shown to bind c-di-GMP through the conserved RxxxR motif of its PilZ domain. A mutant strain carrying a cbp1 deletion was impaired in chemotaxis, a feature that could be restored by genetic complementation. Compared with the wild type strain, the Δcbp1 mutant displayed enhanced aggregation and biofilm formation. The Δcbp1 mutant induced functional nodules when inoculated individually. However, the Δcbp1 mutant was less competitive than the wild type in competitive root colonization and nodulation. These data are in agreement with the hypothesis that the c-di-GMP binding chemoreceptor Cbp1 in A. caulinodans is involved in chemotaxis and nodulation.
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Affiliation(s)
- Yu Sun
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Zhihong Xie
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Fu Sui
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Xiaolin Liu
- Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.,College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Wuzeng Cheng
- Shandong Huibang Bohai Agriculture Development Limited Company, Dongying, China
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Liu W, Sun Y, Shen R, Dang X, Liu X, Sui F, Li Y, Zhang Z, Alexandre G, Elmerich C, Xie Z. A Chemotaxis-Like Pathway of Azorhizobium caulinodans Controls Flagella-Driven Motility, Which Regulates Biofilm Formation, Exopolysaccharide Biosynthesis, and Competitive Nodulation. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:737-749. [PMID: 29424664 DOI: 10.1094/mpmi-12-17-0290-r] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The genome of the Azorhizobium caulinodans ORS571 contains a unique chemotaxis gene cluster (che) including five chemotaxis genes: cheA, cheW, cheY1, cheB, and cheR. Analysis of the role of the chemotaxis cluster of A. caulinodans using deletion mutant strains revealed that CheA or the Che signaling pathway controls chemotaxis behavior and flagella-driven motility and plays important roles in formation of biofilms and production of extracellular polysaccharides (EPS). Furthermore, the deletion mutants (ΔcheA and ΔcheA-R) were defective in competitive adsorption and colonization on the root surface of host plants. In addition, a functional CheA or Che pathway promoted competitive nodulation on roots and stems. Interestingly, a nonflagellated mutant, ΔfliM, displayed a phenotype highly similar to that of the ΔcheA or ΔcheA-R mutant strains. These findings suggest that through controlling flagella-driven motility behavior, the chemotaxis signaling pathway in A. caulinodans coordinates biofilm formation, EPS, and competitive colonization and nodulation.
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Affiliation(s)
- Wei Liu
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Yu Sun
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Rimin Shen
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- 2 Shanxi Agricultural University, Taigu, Shanxi, China
| | - Xiaoxiao Dang
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Xiaolin Liu
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Fu Sui
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Yan Li
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Zhenpeng Zhang
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Gladys Alexandre
- 3 Biochemistry, Cellular and Molecular Biology Department, University of Tennessee, Knoxville, U.S.A.; and
| | | | - Zhihong Xie
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
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A cheZ-Like Gene in Azorhizobium caulinodans Is a Key Gene in the Control of Chemotaxis and Colonization of the Host Plant. Appl Environ Microbiol 2018; 84:AEM.01827-17. [PMID: 29150498 DOI: 10.1128/aem.01827-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 11/01/2017] [Indexed: 02/07/2023] Open
Abstract
Chemotaxis can provide bacteria with competitive advantages for survival in complex environments. The CheZ chemotaxis protein is a phosphatase, affecting the flagellar motor in Escherichia coli by dephosphorylating the response regulator phosphorylated CheY protein (CheY∼P) responsible for clockwise rotation. A cheZ gene has been found in Azorhizobium caulinodans ORS571, in contrast to other rhizobial species studied so far. The CheZ protein in strain ORS571 has a conserved motif similar to that corresponding to the phosphatase active site in E. coli The construction of a cheZ deletion mutant strain and of cheZ mutant strains carrying a mutation in residues of the putative phosphatase active site showed that strain ORS571 participates in chemotaxis and motility, causing a hyperreversal behavior. In addition, the properties of the cheZ deletion mutant revealed that ORS571 CheZ is involved in other physiological processes, since it displayed increased flocculation, biofilm formation, exopolysaccharide (EPS) production, and host root colonization. In particular, it was observed that the expression of several exp genes, involved in EPS synthesis, was upregulated in the cheZ mutant compared to that in the wild type, suggesting that CheZ negatively controls exp gene expression through an unknown mechanism. It is proposed that CheZ influences the Azorhizobium-plant association by negatively regulating early colonization via the regulation of EPS production. This report established that CheZ in A. caulinodans plays roles in chemotaxis and the symbiotic association with the host plant.IMPORTANCE Chemotaxis allows bacteria to swim toward plant roots and is beneficial to the establishment of various plant-microbe associations. The level of CheY phosphorylation (CheY∼P) is central to the chemotaxis signal transduction. The mechanism of the signal termination of CheY∼P remains poorly characterized among Alphaproteobacteria, except for Sinorhizobium meliloti, which does not contain CheZ but which controls CheY∼P dephosphorylation through a phosphate sink mechanism. Azorhizobium caulinodans ORS571, a microsymbiont of Sesbania rostrata, has an orphan cheZ gene besides two cheY genes similar to those in S. meliloti In addition to controlling the chemotaxis response, the CheZ-like protein in strain ORS571 is playing a role by decreasing bacterial adhesion to the host plant, in contrast to the general situation where chemotaxis-associated proteins promote adhesion. In this study, we identified a CheZ-like protein among Alphaproteobacteria functioning in chemotaxis and the A. caulinodans-S. rostrata symbiosis.
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A Novel Regulatory Pathway for K + Uptake in the Legume Symbiont Azorhizobium caulinodans in Which TrkJ Represses the kdpFABC Operon at High Extracellular K + Concentrations. Appl Environ Microbiol 2017; 83:AEM.01197-17. [PMID: 28778893 DOI: 10.1128/aem.01197-17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Accepted: 07/28/2017] [Indexed: 11/20/2022] Open
Abstract
Bacteria have multiple K+ uptake systems. Escherichia coli, for example, has three types of K+ uptake systems, which include the low-K+-inducible KdpFABC system and two constitutive systems, Trk (TrkAG and TrkAH) and Kup. Azorhizobium caulinodans ORS571, a rhizobium that forms nitrogen-fixing nodules on the stems and roots of Sesbania rostrata, also has three types of K+ uptake systems. Through phylogenetic analysis, we found that A. caulinodans has two genes homologous to trkG and trkH, designated trkI and trkJ We also found that trkI is adjacent to trkA in the genome and these two genes are transcribed as an operon; however, trkJ is present at a distinct locus. Our results demonstrated that trkAI, trkJ, and kup were expressed in the wild-type stem nodules, whereas kdpFABC was not. Interestingly, Δkup and Δkup ΔkdpA mutants formed Fix- nodules, while the Δkup ΔtrkA ΔtrkI ΔtrkJ mutant formed Fix+ nodules, suggesting that with the additional deletion of Trk system genes in the Δkup mutant, Fix+ nodule phenotypes were recovered. kdpFABC of the Δkup ΔtrkJ mutant was expressed in stem nodules, but not in the free-living state, under high-K+ conditions. However, kdpFABC of the Δkup ΔtrkA ΔtrkI ΔtrkJ mutant was highly expressed even under high-K+ conditions. The cytoplasmic K+ levels in the Δkup ΔtrkA ΔtrkI mutant, which did not express kdpFABC under high-K+ conditions, were markedly lower than those in the Δkup ΔtrkA ΔtrkI ΔtrkJ mutant. Taking all these results into consideration, we propose that TrkJ is involved in the repression of kdpFABC in response to high external K+ concentrations and that the TrkAI system is unable to function in stem nodules.IMPORTANCE K+ is a major cytoplasmic cation in prokaryotic and eukaryotic cells. Bacteria have multiple K+ uptake systems to control the cytoplasmic K+ levels. In many bacteria, the K+ uptake system KdpFABC is expressed under low-K+ conditions. For years, many researchers have argued over how bacteria sense K+ concentrations. Although KdpD of Escherichia coli is known to sense both cytoplasmic and extracellular K+ concentrations, the detailed mechanism of K+ sensing is still unclear. In this study, we propose that the transmembrane TrkJ protein of Azorhizobium caulinodans acts as a sensor for the extracellular K+ concentration and that high extracellular K+ concentrations repress the expression of KdpFABC via TrkJ.
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Stringent Expression Control of Pathogenic R-body Production in Legume Symbiont Azorhizobium caulinodans. mBio 2017; 8:mBio.00715-17. [PMID: 28743814 PMCID: PMC5527310 DOI: 10.1128/mbio.00715-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
R bodies are insoluble large polymers consisting of small proteins encoded by reb genes and are coiled into cylindrical structures in bacterial cells. They were first discovered in Caedibacter species, which are obligate endosymbionts of paramecia. Caedibacter confers a killer trait on the host paramecia. R-body-producing symbionts are released from their host paramecia and kill symbiont-free paramecia after ingestion. The roles of R bodies have not been explained in bacteria other than Caedibacter. Azorhizobium caulinodans ORS571, a microsymbiont of the legume Sesbania rostrata, carries a reb operon containing four reb genes that are regulated by the repressor PraR. Herein, deletion of the praR gene resulted in R-body formation and death of host plant cells. The rebR gene in the reb operon encodes an activator. Three PraR binding sites and a RebR binding site are present in the promoter region of the reb operon. Expression analyses using strains with mutations within the PraR binding site and/or the RebR binding site revealed that PraR and RebR directly control the expression of the reb operon and that PraR dominantly represses reb expression. Furthermore, we found that the reb operon is highly expressed at low temperatures and that 2-oxoglutarate induces the expression of the reb operon by inhibiting PraR binding to the reb promoter. We conclude that R bodies are toxic not only in paramecium symbiosis but also in relationships between other bacteria and eukaryotic cells and that R-body formation is controlled by environmental factors. Caedibacter species, which are obligate endosymbiotic bacteria of paramecia, produce R bodies, and R-body-producing endosymbionts that are released from their hosts are pathogenic to symbiont-free paramecia. Besides Caedibacter species, R bodies have also been observed in a few free-living bacteria, but the significance of R-body production in these bacteria is still unknown. Recent advances in genome sequencing technologies revealed that many Gram-negative bacteria possess reb genes encoding R-body components, and interestingly, many of them are animal and plant pathogens. Azorhizobium caulinodans, a microsymbiont of the tropical legume Sesbania rostrata, also possesses reb genes. In this study, we demonstrate that A. caulinodans has ability to kill the host plant cells by producing R bodies, suggesting that pathogenicity conferred by an R body might be universal in bacteria possessing reb genes. Furthermore, we provide the first insight into the molecular mechanism underlying the expression of R-body production in response to environmental factors, such as temperature and 2-oxoglutarate.
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A Chemotaxis Receptor Modulates Nodulation during the Azorhizobium caulinodans-Sesbania rostrata Symbiosis. Appl Environ Microbiol 2016; 82:3174-84. [PMID: 26994081 DOI: 10.1128/aem.00230-16] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 03/14/2016] [Indexed: 01/02/2023] Open
Abstract
UNLABELLED Azorhizobium caulinodans ORS571 is a free-living nitrogen-fixing bacterium which can induce nitrogen-fixing nodules both on the root and the stem of its legume host Sesbania rostrata This bacterium, which is an obligate aerobe that moves by means of a polar flagellum, possesses a single chemotaxis signal transduction pathway. The objective of this work was to examine the role that chemotaxis and aerotaxis play in the lifestyle of the bacterium in free-living and symbiotic conditions. In bacterial chemotaxis, chemoreceptors sense environmental changes and transmit this information to the chemotactic machinery to guide motile bacteria to preferred niches. Here, we characterized a chemoreceptor of A. caulinodans containing an N-terminal PAS domain, named IcpB. IcpB is a soluble heme-binding protein that localized at the cell poles. An icpB mutant strain was impaired in sensing oxygen gradients and in chemotaxis response to organic acids. Compared to the wild-type strain, the icpB mutant strain was also affected in the production of extracellular polysaccharides and impaired in flocculation. When inoculated alone, the icpB mutant induced nodules on S. rostrata, but the nodules formed were smaller and had reduced N2-fixing activity. The icpB mutant failed to nodulate its host when inoculated competitively with the wild-type strain. Together, the results identify chemotaxis and sensing of oxygen by IcpB as key regulators of the A. caulinodans-S. rostrata symbiosis. IMPORTANCE Bacterial chemotaxis has been implicated in the establishment of various plant-microbe associations, including that of rhizobial symbionts with their legume host. The exact signal(s) detected by the motile bacteria that guide them to their plant hosts remain poorly characterized. Azorhizobium caulinodans ORS571 is a diazotroph that is a motile and chemotactic rhizobial symbiont of Sesbania rostrata, where it forms nitrogen-fixing nodules on both the roots and the stems of the legume host. We identify here a chemotaxis receptor sensing oxygen in A. caulinodans that is critical for nodulation and nitrogen fixation on the stems and roots of S. rostrata These results identify oxygen sensing and chemotaxis as key regulators of the A. caulinodans-S. rostrata symbiosis.
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Nie X, Li M, Lu B, Zhang Y, Lan L, Chen L, Lu J. Down-regulating overexpressed human Lon in cervical cancer suppresses cell proliferation and bioenergetics. PLoS One 2013; 8:e81084. [PMID: 24260536 PMCID: PMC3834287 DOI: 10.1371/journal.pone.0081084] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 10/08/2013] [Indexed: 01/14/2023] Open
Abstract
The human mitochondrial ATP-dependent Lon protease functions in regulating the metabolism and quality control of proteins and mitochondrial DNA (mtDNA). However, the role of Lon in cancer is not well understood. Therefore, this study was undertaken to investigate the importance of Lon in cervical cancer cells from patients and in established cell lines. Microarray analysis from 30 cancer and 10 normal cervical tissues were analyzed by immunohistochemistry for Lon protein levels. The expression of Lon was also examined by immunoblotting 16 fresh cervical cancer tissues and their respective non-tumor cervical tissues. In all cases, Lon expression was significantly elevated in cervical carcinomas as compared to normal tissues. Augmented Lon expression in tissue microarrays did not vary between age, tumor-node-metastasis grades, or lymph node metastasis. Knocking down Lon in HeLa cervical cancer cells by lentivrial transduction resulted in a substantial decrease in both mRNA and protein levels. Such down-regulation of Lon expression significantly blocked HeLa cell proliferation. In addition, knocking down Lon resulted in decreased cellular bioenergetics as determined by measuring aerobic respiration and glycolysis using the Seahorse XF24 extracellular flux analyzer. Together, these data demonstrate that Lon plays a potential role in the oncogenesis of cervical cancer, and may be a useful biomarker and target in the treatment of cervical cancer. Lon; immunohistochemistry; cervical cancer; cell proliferation; cellular bioenergetics.
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Affiliation(s)
- Xiaobo Nie
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, Zhejiang Provincial Key Laboratory of Medical Genetics, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China ; Department of Biochemistry and Molecular Biology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
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