1
|
Janczarek M, Adamczyk P, Gromada A, Polakowski C, Wengerska K, Bieganowski A. Adaptation of Rhizobium leguminosarum sv. trifolii strains to low temperature stress in both free-living stage and during symbiosis with clover. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 951:175554. [PMID: 39151610 DOI: 10.1016/j.scitotenv.2024.175554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2024] [Revised: 08/12/2024] [Accepted: 08/13/2024] [Indexed: 08/19/2024]
Abstract
Legume-rhizobial symbiosis plays an important role in agriculture and ecological restoration. This process occurs within special new structures, called nodules, formed mainly on legume roots. Soil bacteria, commonly known as rhizobia, fix atmospheric dinitrogen, converting it into a form that can be assimilated by plants. Various environmental factors, including a low temperature, have an impact on the symbiotic efficiency. Nevertheless, the effect of temperature on the phenotypic and symbiotic traits of rhizobia has not been determined in detail to date. Therefore, in this study, the influence of temperature on different cell surface and symbiotic properties of rhizobia was estimated. In total, 31 Rhizobium leguminosarum sv. trifolii strains isolated from root nodules of red clover plants growing in the subpolar and temperate climate regions, which essentially differ in year and day temperature profiles, were chosen for this analysis. Our results showed that temperature has a significant effect on several surface properties of rhizobial cells, such as hydrophobicity, aggregation, and motility. Low temperature also stimulated EPS synthesis and biofilm formation in R. leguminosarum sv. trifolii. This extracellular polysaccharide is known to play an important protective role against different environmental stresses. The strains produced large amounts of EPS under tested temperature conditions that facilitated adherence of rhizobial cells to different surfaces. The high adaptability of these strains to cold stress was also confirmed during symbiosis. Irrespective of their climatic origin, the strains proved to be highly effective in attachment to legume roots and were efficient microsymbionts of clover plants. However, some diversity in the response to low temperature stress was found among the strains. Among them, M16 and R137 proved to be highly competitive and efficient in nodule occupancy and biomass production; thus, they can be potential yield-enhancing inoculants of legumes.
Collapse
Affiliation(s)
- Monika Janczarek
- Department of Industrial and Environmental Microbiology, Institute of Biological Sciences, Maria Curie-Skłodowska University, 19 Akademicka, 20-033 Lublin, Poland.
| | - Paulina Adamczyk
- Department of Industrial and Environmental Microbiology, Institute of Biological Sciences, Maria Curie-Skłodowska University, 19 Akademicka, 20-033 Lublin, Poland.
| | - Anna Gromada
- Department of Industrial and Environmental Microbiology, Institute of Biological Sciences, Maria Curie-Skłodowska University, 19 Akademicka, 20-033 Lublin, Poland.
| | - Cezary Polakowski
- Department of Natural Environment Biogeochemistry, Institute of Agrophysics, Polish Academy of Sciences, 4 Doświadczalna, 20-290 Lublin, Poland.
| | - Karolina Wengerska
- Institute of Biological Basis of Animal Production, University of Life Sciences in Lublin, 13 Akademicka Street, 20-950 Lublin, Poland.
| | - Andrzej Bieganowski
- Department of Natural Environment Biogeochemistry, Institute of Agrophysics, Polish Academy of Sciences, 4 Doświadczalna, 20-290 Lublin, Poland.
| |
Collapse
|
2
|
Gan L, Huang X, He Z, He T. Exopolysaccharide production by salt-tolerant bacteria: Recent advances, current challenges, and future prospects. Int J Biol Macromol 2024; 264:130731. [PMID: 38471615 DOI: 10.1016/j.ijbiomac.2024.130731] [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: 12/26/2023] [Revised: 01/27/2024] [Accepted: 03/06/2024] [Indexed: 03/14/2024]
Abstract
Natural biopolymers derived from exopolysaccharides (EPSs) are considered eco-friendly and sustainable alternatives to available traditional synthetic counterparts. Salt-tolerant bacteria inhabiting harsh ecological niches have evolved a number of unique adaptation strategies allowing them to maintain cellular integrity and assuring their long-term survival; among these, producing EPSs can be adopted as an effective strategy to thrive under high-salt conditions. A great diversity of EPSs from salt-tolerant bacteria have attracted widespread attention recently. Because of factors such as their unique structural, physicochemical, and functional characteristics, EPSs are commercially valuable for the global market and their application potential in various sectors is promising. However, large-scale production and industrial development of these biopolymers are hindered by their low yields and high costs. Consequently, the research progress and future prospects of salt-tolerant bacterial EPSs must be systematically reviewed to further promote their application and commercialization. In this review, the structure and properties of EPSs produced by a variety of salt-tolerant bacterial strains isolated from different sources are summarized. Further, feasible strategies for solving production bottlenecks are discussed, which provides a scientific basis and direct reference for more scientific and rational EPS development.
Collapse
Affiliation(s)
- Longzhan Gan
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Life Sciences, Guizhou University, Guiyang 550025, Guizhou Province, China.
| | - Xin Huang
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Life Sciences, Guizhou University, Guiyang 550025, Guizhou Province, China
| | - Zhicheng He
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Life Sciences, Guizhou University, Guiyang 550025, Guizhou Province, China
| | - Tengxia He
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Life Sciences, Guizhou University, Guiyang 550025, Guizhou Province, China.
| |
Collapse
|
3
|
Alabssawy AN, Hashem AH. Bioremediation of hazardous heavy metals by marine microorganisms: a recent review. Arch Microbiol 2024; 206:103. [PMID: 38358529 PMCID: PMC10869373 DOI: 10.1007/s00203-023-03793-5] [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: 10/22/2023] [Revised: 12/09/2023] [Accepted: 12/11/2023] [Indexed: 02/16/2024]
Abstract
Heavy metals (HMs) like Zn, Cu, Pb, Ni, Cd, and Hg, among others, play a role in several environmental problems. The marine environment is polluted by several contaminants, such as HMs. A variety of physico-chemical methods usually available for sanitation HMs remediation suffer from either limitation. Bioremediation is a promising way of dealing with HMs pollution. Microbes have the ability with various potencies to resist HMs tension. The current review discusses the main sources and influences of HMs, the role of marine microorganisms in HMs bioremediation, as well as the microbial mechanisms for HMs detoxification and transformation. This review paper aims to provide an overview of the bioremediation technologies that are currently available for the removal of HMs ions from industrial and urban effluent by aquatic organisms such as bacteria, fungi, and microalgae, particularly those that are isolated from marine areas. The primary goals are to outline various studies and offer helpful information about the most important aspects of the bioelimination techniques. The biotreatment practices have been primarily divided into three techniques based on this topic. They are biosorption, bioaccumulation, bioleaching, and biotransformation. This article gives the brief view on the research studies about bioremediation of HMs using marine microorganisms. The current review also deals with the critical issues and recent studies based on the HMs biodetoxification using aquatic microorganisms.
Collapse
Affiliation(s)
- Ahmed N Alabssawy
- Marine Science and Fishes Branch, Zoology Department, Faculty of Science, Al-Azhar University, Cairo, 11884, Egypt.
| | - Amr H Hashem
- Botany and Microbiology Department, Faculty of Science, Al-Azhar University, Nasr City, Cairo, 11884, Egypt.
| |
Collapse
|
4
|
Ben Gaied R, Sbissi I, Tarhouni M, Brígido C. Bacterial Endophytes from Legumes Native to Arid Environments Are Promising Tools to Improve Mesorhizobium-Chickpea Symbiosis under Salinity. BIOLOGY 2024; 13:96. [PMID: 38392314 PMCID: PMC10886315 DOI: 10.3390/biology13020096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 01/26/2024] [Accepted: 02/01/2024] [Indexed: 02/24/2024]
Abstract
Symbiotic nitrogen fixation is a major contributor of N in agricultural ecosystems, but the establishment of legume-rhizobium symbiosis is highly affected by soil salinity. Our interest is focused on the use of non-rhizobial endophytes to assist the symbiosis between chickpea and its microsymbiont under salinity to avoid loss of production and fertility. Our aims were (1) to investigate the impact of salinity on both symbiotic partners; including on early events of the Mesorhizobium-chickpea symbiosis, and (2) to evaluate the potential of four non-rhizobial endophytes isolated from legumes native to arid regions (Phyllobacterium salinisoli, P. ifriqiyense, Xanthomonas translucens, and Cupriavidus respiraculi) to promote chickpea growth and nodulation under salinity. Our results show a significant reduction in chickpea seed germination rate and in the microsymbiont Mesorhizobium ciceri LMS-1 growth under different levels of salinity. The composition of phenolic compounds in chickpea root exudates significantly changed when the plants were subjected to salinity, which in turn affected the nod genes expression in LMS-1. Furthermore, the LMS-1 response to root exudate stimuli was suppressed by the presence of salinity (250 mM NaCl). On the contrary, a significant upregulation of exoY and otsA genes, which are involved in exopolysaccharide and trehalose biosynthesis, respectively, was registered in salt-stressed LMS-1 cells. In addition, chickpea co-inoculation with LMS-1 along with the consortium containing two non-rhizobial bacterial endophytes, P. salinisoli and X. translucens, resulted in significant improvement of the chickpea growth and the symbiotic performance of LMS-1 under salinity. These results indicate that this non-rhizobial endophytic consortium may be an appropriate ecological and safe tool to improve chickpea growth and its adaptation to salt-degraded soils.
Collapse
Affiliation(s)
- Roukaya Ben Gaied
- Laboratory of Pastoral Ecosystems and Promotion of Spontaneous Plants and Associated Micro-Organisms, Institute of Arid Lands, University of Gabes, Medenine 4119, Tunisia
- MED-Mediterranean Institute for Agriculture, Environment and Development, Universidade de Évora, Pólo da Mitra, Ap. 94, 7006-554 Évora, Portugal
| | - Imed Sbissi
- Laboratory of Pastoral Ecosystems and Promotion of Spontaneous Plants and Associated Micro-Organisms, Institute of Arid Lands, University of Gabes, Medenine 4119, Tunisia
| | - Mohamed Tarhouni
- Laboratory of Pastoral Ecosystems and Promotion of Spontaneous Plants and Associated Micro-Organisms, Institute of Arid Lands, University of Gabes, Medenine 4119, Tunisia
| | - Clarisse Brígido
- MED-Mediterranean Institute for Agriculture, Environment and Development & CHANGE-Global Change and Sustainability Institute, Institute for Advanced Studies and Research, Universidade de Évora, Pólo da Mitra, Ap. 94, 7006-554 Évora, Portugal
| |
Collapse
|
5
|
Kim J, Jeong JP, Kim Y, Jung S. Physicochemical and Rheological Properties of Succinoglycan Overproduced by Sinorhizobium meliloti 1021 Mutant. Polymers (Basel) 2024; 16:244. [PMID: 38257044 PMCID: PMC10819756 DOI: 10.3390/polym16020244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 01/24/2024] Open
Abstract
Commercial bacterial exopolysaccharide (EPS) applications have been gaining interest; therefore, strains that provide higher yields are required for industrial-scale processes. Succinoglycan (SG) is a type of bacterial anionic exopolysaccharide produced by Rhizobium, Agrobacterium, and other soil bacterial species. SG has been widely used as a pharmaceutical, cosmetic, and food additive based on its properties as a thickener, texture enhancer, emulsifier, stabilizer, and gelling agent. An SG-overproducing mutant strain (SMC1) was developed from Sinorhizobium meliloti 1021 through N-methyl-N'-nitro-N-nitrosoguanidine (NTG) mutation, and the physicochemical and rheological properties of SMC1-SG were analyzed. SMC1 produced (22.3 g/L) 3.65-fold more SG than did the wild type. Succinoglycan (SMC1-SG) overproduced by SMC1 was structurally characterized by FT-IR and 1H NMR spectroscopy. The molecular weights of SG and SMC1-SG were 4.20 × 105 and 4.80 × 105 Da, respectively, as determined by GPC. Based on DSC and TGA, SMC1-SG exhibited a higher endothermic peak (90.9 °C) than that of SG (77.2 °C). Storage modulus (G') and loss modulus (G″) measurements during heating and cooling showed that SMC1-SG had improved thermal behavior compared to that of SG, with intersections at 74.9 °C and 72.0 °C, respectively. The SMC1-SG's viscosity reduction pattern was maintained even at high temperatures (65 °C). Gelation by metal cations was observed in Fe3+ and Cr3+ solutions for both SG and SMC1-SG. Antibacterial activities of SG and SMC1-SG against Escherichia coli and Staphylococcus aureus were also observed. Therefore, like SG, SMC1-SG may be a potential biomaterial for pharmaceutical, cosmetic, and food industries.
Collapse
Affiliation(s)
- Jaeyul Kim
- Department of Bioscience and Biotechnology, Microbial Carbohydrate Resource Bank (MCRB), Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea; (J.K.); (J.-p.J.); (Y.K.)
| | - Jae-pil Jeong
- Department of Bioscience and Biotechnology, Microbial Carbohydrate Resource Bank (MCRB), Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea; (J.K.); (J.-p.J.); (Y.K.)
| | - Yohan Kim
- Department of Bioscience and Biotechnology, Microbial Carbohydrate Resource Bank (MCRB), Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea; (J.K.); (J.-p.J.); (Y.K.)
| | - Seunho Jung
- Department of System Biotechnology, Microbial Carbohydrate Resource Bank (MCRB), Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea
| |
Collapse
|
6
|
Wei X, Chen Z, Liu A, Yang L, Xu Y, Cao M, He N. Advanced strategies for metabolic engineering of Bacillus to produce extracellular polymeric substances. Biotechnol Adv 2023; 67:108199. [PMID: 37330153 DOI: 10.1016/j.biotechadv.2023.108199] [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: 03/05/2023] [Revised: 05/24/2023] [Accepted: 06/11/2023] [Indexed: 06/19/2023]
Abstract
Extracellular polymeric substances are mainly synthesized via a variety of biosynthetic pathways in bacteria. Bacilli-sourced extracellular polymeric substances, such as exopolysaccharides (EPS) and poly-γ-glutamic acid (γ-PGA), can serve as active ingredients and hydrogels, and have other important industrial applications. However, the functional diversity and widespread applications of these extracellular polymeric substances, are hampered by their low yields and high costs. Biosynthesis of extracellular polymeric substances is very complex in Bacillus, and there is no detailed elucidation of the reactions and regulations among various metabolic pathways. Therefore, a better understanding of the metabolic mechanisms is required to broaden the functions and increase the yield of extracellular polymeric substances. This review systematically summarizes the biosynthesis and metabolic mechanisms of extracellular polymeric substances in Bacillus, providing an in-depth understanding of the relationships between EPS and γ-PGA synthesis. This review provides a better clarification of Bacillus metabolic mechanisms during extracellular polymeric substance secretion and thus benefits their application and commercialization.
Collapse
Affiliation(s)
- Xiaoyu Wei
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China; The Key Lab for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen 361005, China
| | - Zhen Chen
- College of Life Science, Xinyang Normal University, Xinyang 464000, China.
| | - Ailing Liu
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China; The Key Lab for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen 361005, China
| | - Lijie Yang
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China; The Key Lab for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen 361005, China
| | - Yiyuan Xu
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China; The Key Lab for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen 361005, China
| | - Mingfeng Cao
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China; The Key Lab for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen 361005, China; Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen 361005, China.
| | - Ning He
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China; The Key Lab for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen 361005, China.
| |
Collapse
|
7
|
Bustamante JA, Ceron JS, Gao IT, Ramirez HA, Aviles MV, Bet Adam D, Brice JR, Cuellar RA, Dockery E, Jabagat MK, Karp DG, Lau JKO, Li S, Lopez-Magaña R, Moore RR, Morin BKR, Nzongo J, Rezaeihaghighi Y, Sapienza-Martinez J, Tran TTK, Huang Z, Duthoy AJ, Barnett MJ, Long SR, Chen JC. A protease and a lipoprotein jointly modulate the conserved ExoR-ExoS-ChvI signaling pathway critical in Sinorhizobium meliloti for symbiosis with legume hosts. PLoS Genet 2023; 19:e1010776. [PMID: 37871041 PMCID: PMC10659215 DOI: 10.1371/journal.pgen.1010776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 11/20/2023] [Accepted: 10/11/2023] [Indexed: 10/25/2023] Open
Abstract
Sinorhizobium meliloti is a model alpha-proteobacterium for investigating microbe-host interactions, in particular nitrogen-fixing rhizobium-legume symbioses. Successful infection requires complex coordination between compatible host and endosymbiont, including bacterial production of succinoglycan, also known as exopolysaccharide-I (EPS-I). In S. meliloti EPS-I production is controlled by the conserved ExoS-ChvI two-component system. Periplasmic ExoR associates with the ExoS histidine kinase and negatively regulates ChvI-dependent expression of exo genes, necessary for EPS-I synthesis. We show that two extracytoplasmic proteins, LppA (a lipoprotein) and JspA (a lipoprotein and a metalloprotease), jointly influence EPS-I synthesis by modulating the ExoR-ExoS-ChvI pathway and expression of genes in the ChvI regulon. Deletions of jspA and lppA led to lower EPS-I production and competitive disadvantage during host colonization, for both S. meliloti with Medicago sativa and S. medicae with M. truncatula. Overexpression of jspA reduced steady-state levels of ExoR, suggesting that the JspA protease participates in ExoR degradation. This reduction in ExoR levels is dependent on LppA and can be replicated with ExoR, JspA, and LppA expressed exogenously in Caulobacter crescentus and Escherichia coli. Akin to signaling pathways that sense extracytoplasmic stress in other bacteria, JspA and LppA may monitor periplasmic conditions during interaction with the plant host to adjust accordingly expression of genes that contribute to efficient symbiosis. The molecular mechanisms underlying host colonization in our model system may have parallels in related alpha-proteobacteria.
Collapse
Affiliation(s)
- Julian A. Bustamante
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Josue S. Ceron
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Ivan Thomas Gao
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Hector A. Ramirez
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Milo V. Aviles
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Demsin Bet Adam
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Jason R. Brice
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Rodrigo A. Cuellar
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Eva Dockery
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Miguel Karlo Jabagat
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Donna Grace Karp
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Joseph Kin-On Lau
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Suling Li
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Raymondo Lopez-Magaña
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Rebecca R. Moore
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Bethany Kristi R. Morin
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Juliana Nzongo
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Yasha Rezaeihaghighi
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Joseph Sapienza-Martinez
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Tuyet Thi Kim Tran
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Zhenzhong Huang
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Aaron J. Duthoy
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Melanie J. Barnett
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Sharon R. Long
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Joseph C. Chen
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| |
Collapse
|
8
|
Yang J, Zhang Q, Zhang G, Shang G. Recombineering-Mediated Sinorhizobium meliloti Rm1021 Gene Deletion. Curr Microbiol 2023; 80:76. [PMID: 36650293 DOI: 10.1007/s00284-023-03188-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 01/09/2023] [Indexed: 01/19/2023]
Abstract
Sinorhizobium meliloti Rm1021 (S. meliloti Rm1021) is a Gram-negative, soil-dwelling α-proteobacterium which serves as a model microorganism for the studies of symbiotic nitrogen fixation. The S. meliloti Rm1021 genome consists of one chromosome and two megaplasmids, pSymA and pSymB. Gene deletion is an essential tool for the elucidation of gene function and generation of mutants with improved properties. However, only two gene deletion methods, counterselectable marker sacB-based and FLP/FRT, Cre/loxP site-specific recombination, have been reported for S. meliloti Rm1021 gene deletion. Both methods require time-consuming and tedious gene cloning and conjugation steps. Herein, a λ Red recombineering-mediated gene deletion strategy is reported. The mutant was obtained via electroporating overlap-extension PCR-generated linear targeting DNA into Red-proficient cells. One gene each from the S. meliloti Rm1021 chromosome, megaplasmid SymA and pSymB was deleted, with deletion efficiency up to 100%. The straightforward and highly efficient recombineering procedure holds the promise to be a general gene manipulation method for S. meliloti Rm1021.
Collapse
Affiliation(s)
- Jun Yang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, No. 1 Wenyuan Rd., Xixia District, Nanjing, 210023, Jiangsu, People's Republic of China
| | - Qiong Zhang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, No. 1 Wenyuan Rd., Xixia District, Nanjing, 210023, Jiangsu, People's Republic of China
| | - Guoyi Zhang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, No. 1 Wenyuan Rd., Xixia District, Nanjing, 210023, Jiangsu, People's Republic of China
| | - Guangdong Shang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, No. 1 Wenyuan Rd., Xixia District, Nanjing, 210023, Jiangsu, People's Republic of China.
| |
Collapse
|
9
|
Zhang Y, Gallant É, Park JD, Seyedsayamdost MR. The Small-Molecule Language of Dynamic Microbial Interactions. Annu Rev Microbiol 2022; 76:641-660. [PMID: 35679616 PMCID: PMC10171915 DOI: 10.1146/annurev-micro-042722-091052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Although microbes are routinely grown in monocultures in the laboratory, they are almost never encountered as single species in the wild. Our ability to detect and identify new microorganisms has advanced significantly in recent years, but our understanding of the mechanisms that mediate microbial interactions has lagged behind. What makes this task more challenging is that microbial alliances can be dynamic, consisting of multiple phases. The transitions between phases, and the interactions in general, are often mediated by a chemical language consisting of small molecules, also referred to as secondary metabolites or natural products. In this microbial lexicon, the molecules are like words and through their effects on recipient cells they convey meaning. The current review highlights three dynamic microbial interactions in which some of the words and their meanings have been characterized, especially those that mediate transitions in selected multiphasic associations. These systems provide insights into the principles that govern microbial symbioses and a playbook for interrogating similar associations in diverse ecological niches. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Collapse
Affiliation(s)
- Yifan Zhang
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA; ,
| | - Étienne Gallant
- Department of Chemistry, Princeton University, Princeton, New Jersey, USA; ,
| | - Jong-Duk Park
- Department of Chemistry, Princeton University, Princeton, New Jersey, USA; ,
| | - Mohammad R Seyedsayamdost
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA; , .,Department of Chemistry, Princeton University, Princeton, New Jersey, USA; ,
| |
Collapse
|
10
|
Eardly B, Meor Osman WA, Ardley J, Zandberg J, Gollagher M, van Berkum P, Elia P, Marinova D, Seshadri R, Reddy TBK, Ivanova N, Pati A, Woyke T, Kyrpides N, Loedolff M, Laird DW, Reeve W. The Genome of the Acid Soil-Adapted Strain Rhizobium favelukesii OR191 Encodes Determinants for Effective Symbiotic Interaction With Both an Inverted Repeat Lacking Clade and a Phaseoloid Legume Host. Front Microbiol 2022; 13:735911. [PMID: 35495676 PMCID: PMC9048898 DOI: 10.3389/fmicb.2022.735911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Accepted: 02/10/2022] [Indexed: 11/15/2022] Open
Abstract
Although Medicago sativa forms highly effective symbioses with the comparatively acid-sensitive genus Ensifer, its introduction into acid soils appears to have selected for symbiotic interactions with acid-tolerant R. favelukesii strains. Rhizobium favelukesii has the unusual ability of being able to nodulate and fix nitrogen, albeit sub-optimally, not only with M. sativa but also with the promiscuous host Phaseolus vulgaris. Here we describe the genome of R. favelukesii OR191 and genomic features important for the symbiotic interaction with both of these hosts. The OR191 draft genome contained acid adaptation loci, including the highly acid-inducible lpiA/acvB operon and olsC, required for production of lysine- and ornithine-containing membrane lipids, respectively. The olsC gene was also present in other acid-tolerant Rhizobium strains but absent from the more acid-sensitive Ensifer microsymbionts. The OR191 symbiotic genes were in general more closely related to those found in Medicago microsymbionts. OR191 contained the nodA, nodEF, nodHPQ, and nodL genes for synthesis of polyunsaturated, sulfated and acetylated Nod factors that are important for symbiosis with Medicago, but contained a truncated nodG, which may decrease nodulation efficiency with M. sativa. OR191 contained an E. meliloti type BacA, which has been shown to specifically protect Ensifer microsymbionts from Medicago nodule-specific cysteine-rich peptides. The nitrogen fixation genes nifQWZS were present in OR191 and P. vulgaris microsymbionts but absent from E. meliloti-Medicago microsymbionts. The ability of OR191 to nodulate and fix nitrogen symbiotically with P. vulgaris indicates that this host has less stringent requirements for nodulation than M. sativa but may need rhizobial strains that possess nifQWZS for N2-fixation to occur. OR191 possessed the exo genes required for the biosynthesis of succinoglycan, which is required for the Ensifer-Medicago symbiosis. However, 1H-NMR spectra revealed that, in the conditions tested, OR191 exopolysaccharide did not contain a succinyl substituent but instead contained a 3-hydroxybutyrate moiety, which may affect its symbiotic performance with Medicago hosts. These findings provide a foundation for the genetic basis of nodulation requirements and symbiotic effectiveness with different hosts.
Collapse
Affiliation(s)
- Bertrand Eardly
- Berks College, Penn State University, Reading, PA, United States
| | - Wan Adnawani Meor Osman
- Centre for Crop and Food Innovation, College of Science, Health, Engineering and Education, Food Futures Institute, Murdoch University, Murdoch, WA, Australia
| | - Julie Ardley
- Centre for Crop and Food Innovation, College of Science, Health, Engineering and Education, Food Futures Institute, Murdoch University, Murdoch, WA, Australia
| | - Jaco Zandberg
- Centre for Crop and Food Innovation, College of Science, Health, Engineering and Education, Food Futures Institute, Murdoch University, Murdoch, WA, Australia
| | - Margaret Gollagher
- Murdoch University Associate, Murdoch, WA, Australia.,Sustainability and Biosecurity, Department of Primary Industries and Regional Development, South Perth, WA, Australia
| | - Peter van Berkum
- Soybean Genomics and Improvement Laboratory, United States Department of Agriculture, Beltsville, MD, United States
| | - Patrick Elia
- Soybean Genomics and Improvement Laboratory, United States Department of Agriculture, Beltsville, MD, United States
| | - Dora Marinova
- Curtin University Sustainability Policy Institute, Curtin University, Bentley, WA, Australia
| | - Rekha Seshadri
- Department of Energy (DOE) Joint Genome Institute, Berkeley, CA, United States
| | - T B K Reddy
- Department of Energy (DOE) Joint Genome Institute, Berkeley, CA, United States
| | - Natalia Ivanova
- Department of Energy (DOE) Joint Genome Institute, Berkeley, CA, United States
| | - Amrita Pati
- Department of Energy (DOE) Joint Genome Institute, Berkeley, CA, United States
| | - Tanja Woyke
- Department of Energy (DOE) Joint Genome Institute, Berkeley, CA, United States
| | - Nikos Kyrpides
- Department of Energy (DOE) Joint Genome Institute, Berkeley, CA, United States
| | - Matthys Loedolff
- Centre for Crop and Food Innovation, College of Science, Health, Engineering and Education, Food Futures Institute, Murdoch University, Murdoch, WA, Australia
| | - Damian W Laird
- Centre for Water Energy and Waste, Harry Butler Institute, Murdoch University, Murdoch, WA, Australia
| | - Wayne Reeve
- Centre for Crop and Food Innovation, College of Science, Health, Engineering and Education, Food Futures Institute, Murdoch University, Murdoch, WA, Australia
| |
Collapse
|
11
|
Pirhanov GG. Sinorhizobium meliloti AS A PERSPECTIVE OBJECT FOR MODERN BIOTECHNOLOGY. BIOTECHNOLOGIA ACTA 2021. [DOI: 10.15407/biotech14.06.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Sinorhizobium meliloti is a Gram-negative soil nitrogen-fixing bacterium that increases the yield of legumes. There is information in the literature about the complete genome sequence of this bacterium, in addition, the polysaccharide composition of the biofilm, which is actively involved in nitrogen fixation, has been studied. The well-known nucleotide sequence, as well as the genetic and biochemical features of S. meliloti make this organism an ideal model for biotechnological research. The purpose of this work was to analyze the current data provided in the literature on the symbiotic interaction of Sinorhizobium meliloti with the host plant, and to characterize the main directions of the use of this bacterium in agriculture, bioremediation and medicine.
Collapse
|
12
|
Li C, Yu Y, Fang A, Feng D, Du M, Tang A, Chen S, Li A. Insight into biosorption of heavy metals by extracellular polymer substances and the improvement of the efficacy: a review. Lett Appl Microbiol 2021; 75:1064-1073. [PMID: 34562275 DOI: 10.1111/lam.13563] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 08/26/2021] [Accepted: 09/01/2021] [Indexed: 01/21/2023]
Abstract
Heavy metals are continuously released into aquatic environments in which they accumulate. This phenomenon endangers public health because heavy metals accumulate along the food chain. However, conventional remediation methods are inefficient, expensive and yield toxic intermediate products, which adversely affect the environment. The discovery of green bio-adsorbents such as microbial extracellular polymer substance (EPS) has quickly attracted considerable worldwide attention because of their low cost, high removal efficiency of heavy metals and industrial availability. Hence, this review considers the sources, hazards and treatment methods of heavy metals pollution, particularly the biosorption mechanism of EPS to heavy metals and the influencing factors of the bio-adsorption process, which are significant in the efficient removal of heavy metals-containing wastewater treatment. This review also focuses on strengthening the process of EPS adsorption of heavy metals, which can further contribute to heavy metals removal. Finally, it has been proposed that improving the yield, stability, selectivity and recoverability of EPS is the key direction of further research.
Collapse
Affiliation(s)
- C Li
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, People's Republic of China
| | - Y Yu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, People's Republic of China
| | - A Fang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, People's Republic of China
| | - D Feng
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, People's Republic of China
| | - M Du
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, People's Republic of China
| | - A Tang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, People's Republic of China
| | - S Chen
- School of Municipal and Environmental Engineering, Jilin University of Architecture and Technology, Changchun, People's Republic of China
| | - A Li
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, People's Republic of China.,School of Municipal and Environmental Engineering, Jilin University of Architecture and Technology, Changchun, People's Republic of China
| |
Collapse
|
13
|
Qiu X, Gao T, Yang J, Wang E, Liu L, Yuan H. Water-Soluble Humic Materials Modulating Metabolism and Triggering Stress Defense in Sinorhizobium fredii. Microbiol Spectr 2021; 9:e0029321. [PMID: 34479412 PMCID: PMC8552645 DOI: 10.1128/spectrum.00293-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 07/29/2021] [Indexed: 11/23/2022] Open
Abstract
Bacteria have evolved a series of mechanisms to maintain their survival and reproduction in changeable and stressful environments. In-depth understanding of these mechanisms can allow for better developing and utilizing of bacteria with various biological functions. In this study, we found that water-soluble humic materials (WSHM), a well-known environment-friendly plant growth biostimulant, significantly promoted the free-living growth and survival of Sinorhizobium fredii CCBAU45436 in a bell-shaped, dose-dependent manner, along with more-efficient carbon source consumption and relief of medium acidification. By using RNA-Seq analysis, a total of 1,136 genes significantly up-/downregulated by external addition of WSHM were identified under test conditions. These differentially expressed genes (DEGs) were enriched in functional categories related to carbon/nitrogen metabolism, cellular stress response, and genetic information processing. Further protein-protein interaction (PPI) network analysis and reverse genetic engineering indicated that WSHM might reprogram the transcriptome through inhibiting the expression of key hub gene rsh, which encodes a bifunctional enzyme catalyzing synthesis and hydrolysis of the "magic spot" (p)ppGpp. In addition, the root colonization and viability in soil of S. fredii CCBAU45436 were increased by WSHM. These findings provide us with new insights into how WSHM benefit bacterial adaptations and demonstrate great application value to be a unique inoculant additive. IMPORTANCE Sinorhizobium fredii CCBAU45436 is a highly effective, fast-growing rhizobium that can establish symbiosis with multiple soybean cultivars. However, it is difficult to maintain the high-density effective viable cells in the rhizobial inoculant for the stressful conditions during production, storage, transport, and application. Here, we showed that WSHM greatly increased the viable cells of S. fredii CCBAU45436 in culture, modulating metabolism and triggering stress defense. The root colonization and viability in soil of S. fredii CCBAU45436 were also increased by WSHM. Our results shed new insights into the effects of WSHM on bacteria and the importance of metabolism and stress defense during the bacteria's whole life. In addition, the functional mechanism of WSHM may provide candidate genes for improving environmental adaptability and application potential of bacteria through genetic engineering.
Collapse
Affiliation(s)
- Xiaoqian Qiu
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbiology, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Tongguo Gao
- College of Life Sciences, Hebei Agricultural University, Baoding, China
| | - Jinshui Yang
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbiology, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Entao Wang
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Liang Liu
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbiology, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Hongli Yuan
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbiology, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| |
Collapse
|
14
|
Mendoza-Suárez M, Andersen SU, Poole PS, Sánchez-Cañizares C. Competition, Nodule Occupancy, and Persistence of Inoculant Strains: Key Factors in the Rhizobium-Legume Symbioses. FRONTIERS IN PLANT SCIENCE 2021; 12:690567. [PMID: 34489993 PMCID: PMC8416774 DOI: 10.3389/fpls.2021.690567] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 07/19/2021] [Indexed: 05/06/2023]
Abstract
Biological nitrogen fixation by Rhizobium-legume symbioses represents an environmentally friendly and inexpensive alternative to the use of chemical nitrogen fertilizers in legume crops. Rhizobial inoculants, applied frequently as biofertilizers, play an important role in sustainable agriculture. However, inoculants often fail to compete for nodule occupancy against native rhizobia with inferior nitrogen-fixing abilities, resulting in low yields. Strains with excellent performance under controlled conditions are typically selected as inoculants, but the rates of nodule occupancy compared to native strains are rarely investigated. Lack of persistence in the field after agricultural cycles, usually due to the transfer of symbiotic genes from the inoculant strain to naturalized populations, also limits the suitability of commercial inoculants. When rhizobial inoculants are based on native strains with a high nitrogen fixation ability, they often have superior performance in the field due to their genetic adaptations to the local environment. Therefore, knowledge from laboratory studies assessing competition and understanding how diverse strains of rhizobia behave, together with assays done under field conditions, may allow us to exploit the effectiveness of native populations selected as elite strains and to breed specific host cultivar-rhizobial strain combinations. Here, we review current knowledge at the molecular level on competition for nodulation and the advances in molecular tools for assessing competitiveness. We then describe ongoing approaches for inoculant development based on native strains and emphasize future perspectives and applications using a multidisciplinary approach to ensure optimal performance of both symbiotic partners.
Collapse
Affiliation(s)
| | - Stig U. Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Philip S. Poole
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | | |
Collapse
|
15
|
A conserved rhizobial peptidase that interacts with host-derived symbiotic peptides. Sci Rep 2021; 11:11779. [PMID: 34083727 PMCID: PMC8175422 DOI: 10.1038/s41598-021-91394-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 05/24/2021] [Indexed: 02/07/2023] Open
Abstract
In the Medicago truncatula-Sinorhizobium meliloti symbiosis, chemical signaling initiates rhizobial infection of root nodule tissue, where a large portion of the bacteria are endocytosed into root nodule cells to function in nitrogen-fixing organelles. These intracellular bacteria are subjected to an arsenal of plant-derived nodule-specific cysteine-rich (NCR) peptides, which induce the physiological changes that accompany nitrogen fixation. NCR peptides drive these intracellular bacteria toward terminal differentiation. The bacterial peptidase HrrP was previously shown to degrade host-derived NCR peptides and give the bacterial symbionts greater fitness at the expense of host fitness. The hrrP gene is found in roughly 10% of Sinorhizobium isolates, as it is carried on an accessory plasmid. The objective of the present study is to identify peptidase genes in the core genome of S. meliloti that modulate symbiotic outcome in a manner similar to the accessory hrrP gene. In an overexpression screen of annotated peptidase genes, we identified one such symbiosis-associated peptidase (sap) gene, sapA (SMc00451). When overexpressed, sapA leads to a significant decrease in plant fitness. Its promoter is active in root nodules, with only weak expression evident under free-living conditions. The SapA enzyme can degrade a broad range of NCR peptides in vitro.
Collapse
|
16
|
Castellani LG, Luchetti A, Nilsson JF, Pérez-Giménez J, Wegener C, Schlüter A, Pühler A, Lagares A, Brom S, Pistorio M, Niehaus K, Torres Tejerizo GA. Exopolysaccharide Characterization of Rhizobium favelukesii LPU83 and Its Role in the Symbiosis With Alfalfa. FRONTIERS IN PLANT SCIENCE 2021; 12:642576. [PMID: 33643369 PMCID: PMC7902896 DOI: 10.3389/fpls.2021.642576] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 01/20/2021] [Indexed: 05/03/2023]
Abstract
One of the greatest inputs of available nitrogen into the biosphere occurs through the biological N2-fixation to ammonium as result of the symbiosis between rhizobia and leguminous plants. These interactions allow increased crop yields on nitrogen-poor soils. Exopolysaccharides (EPS) are key components for the establishment of an effective symbiosis between alfalfa and Ensifer meliloti, as bacteria that lack EPS are unable to infect the host plants. Rhizobium favelukesii LPU83 is an acid-tolerant rhizobia strain capable of nodulating alfalfa but inefficient to fix nitrogen. Aiming to identify the molecular determinants that allow R. favelukesii to infect plants, we studied its EPS biosynthesis. LPU83 produces an EPS I identical to the one present in E. meliloti, but the organization of the genes involved in its synthesis is different. The main gene cluster needed for the synthesis of EPS I in E. meliloti, is split into three different sections in R. favelukesii, which probably arose by a recent event of horizontal gene transfer. A R. favelukesii strain devoided of all the genes needed for the synthesis of EPS I is still able to infect and nodulate alfalfa, suggesting that attention should be directed to other molecules involved in the development of the symbiosis.
Collapse
Affiliation(s)
- Lucas G. Castellani
- Instituto de Biotecnología y Biología Molecular (IBBM), CCT-La Plata, CONICET, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Abril Luchetti
- Instituto de Biotecnología y Biología Molecular (IBBM), CCT-La Plata, CONICET, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Juliet F. Nilsson
- Instituto de Biotecnología y Biología Molecular (IBBM), CCT-La Plata, CONICET, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Julieta Pérez-Giménez
- Instituto de Biotecnología y Biología Molecular (IBBM), CCT-La Plata, CONICET, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | | | | | | | - Antonio Lagares
- Instituto de Biotecnología y Biología Molecular (IBBM), CCT-La Plata, CONICET, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Susana Brom
- Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Mariano Pistorio
- Instituto de Biotecnología y Biología Molecular (IBBM), CCT-La Plata, CONICET, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | | | - Gonzalo A. Torres Tejerizo
- Instituto de Biotecnología y Biología Molecular (IBBM), CCT-La Plata, CONICET, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| |
Collapse
|
17
|
Sun X, Zhang J. Bacterial exopolysaccharides: Chemical structures, gene clusters and genetic engineering. Int J Biol Macromol 2021; 173:481-490. [PMID: 33493567 DOI: 10.1016/j.ijbiomac.2021.01.139] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/18/2021] [Accepted: 01/19/2021] [Indexed: 11/25/2022]
Abstract
In recent decades, the composition, structure, biosynthesis, and function of bacterial extracellular polysaccharides (EPS) have been extensively studied. EPS are synthesized through different biosynthetic pathways. The genes responsible for EPS synthesis are usually clustered on the genome or large plasmids of bacteria. Generally, different EPS synthesis gene clusters direct the synthesis of EPS with different chemical structures and biological activities. A better understanding of the gene functions involved in EPS biosynthesis is critical for the production of EPS with special biological activities. Genetic engineering methods are usually used to study EPS synthesis related genes. This review organizes the available information on EPS, including their structures, synthesis of related genes, and highlights the research progress of modifying EPS gene clusters through gene-editing methods.
Collapse
Affiliation(s)
- Xiaqing Sun
- Center for Molecular Metabolism, Nanjing University of Science & Technology, Nanjing, China
| | - Jianfa Zhang
- Center for Molecular Metabolism, Nanjing University of Science & Technology, Nanjing, China.
| |
Collapse
|
18
|
Goyal RK, Schmidt MA, Hynes MF. Molecular Biology in the Improvement of Biological Nitrogen Fixation by Rhizobia and Extending the Scope to Cereals. Microorganisms 2021; 9:microorganisms9010125. [PMID: 33430332 PMCID: PMC7825764 DOI: 10.3390/microorganisms9010125] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 12/29/2020] [Accepted: 01/06/2021] [Indexed: 11/16/2022] Open
Abstract
The contribution of biological nitrogen fixation to the total N requirement of food and feed crops diminished in importance with the advent of synthetic N fertilizers, which fueled the “green revolution”. Despite being environmentally unfriendly, the synthetic versions gained prominence primarily due to their low cost, and the fact that most important staple crops never evolved symbiotic associations with bacteria. In the recent past, advances in our knowledge of symbiosis and nitrogen fixation and the development and application of recombinant DNA technology have created opportunities that could help increase the share of symbiotically-driven nitrogen in global consumption. With the availability of molecular biology tools, rapid improvements in symbiotic characteristics of rhizobial strains became possible. Further, the technology allowed probing the possibility of establishing a symbiotic dialogue between rhizobia and cereals. Because the evolutionary process did not forge a symbiotic relationship with the latter, the potential of molecular manipulations has been tested to incorporate a functional mechanism of nitrogen reduction independent of microbes. In this review, we discuss various strategies applied to improve rhizobial strains for higher nitrogen fixation efficiency, more competitiveness and enhanced fitness under unfavorable environments. The challenges and progress made towards nitrogen self-sufficiency of cereals are also reviewed. An approach to integrate the genetically modified elite rhizobia strains in crop production systems is highlighted.
Collapse
Affiliation(s)
- Ravinder K. Goyal
- Lacombe Research and Development Centre, Agriculture and Agri-Food Canada, Lacombe, AB T4L 1W1, Canada;
- Correspondence:
| | - Maria Augusta Schmidt
- Lacombe Research and Development Centre, Agriculture and Agri-Food Canada, Lacombe, AB T4L 1W1, Canada;
- Department of Biological Sciences, University of Calgary, 2500 University Dr NW, Calgary, AB T2N 1N4, Canada;
| | - Michael F. Hynes
- Department of Biological Sciences, University of Calgary, 2500 University Dr NW, Calgary, AB T2N 1N4, Canada;
| |
Collapse
|
19
|
Primo E, Bogino P, Cossovich S, Foresto E, Nievas F, Giordano W. Exopolysaccharide II Is Relevant for the Survival of Sinorhizobium meliloti under Water Deficiency and Salinity Stress. Molecules 2020; 25:E4876. [PMID: 33105680 PMCID: PMC7659973 DOI: 10.3390/molecules25214876] [Citation(s) in RCA: 4] [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: 08/29/2020] [Revised: 10/12/2020] [Accepted: 10/20/2020] [Indexed: 11/16/2022] Open
Abstract
Sinorhizobium meliloti is a soil bacterium of great agricultural importance because of its ability to fix atmospheric nitrogen in symbiotic association with alfalfa (Medicago sativa) roots. We looked into the involvement of exopolysaccharides (EPS) in its survival when exposed to different environmental stressors, as well as in bacteria-bacteria and bacteria-substrate interactions. The strains used were wild-type Rm8530 and two strains that are defective in the biosynthesis of EPS II: wild-type Rm1021, which has a non-functional expR locus, and mutant Rm8530 expA. Under stress by water deficiency, Rm8530 remained viable and increased in number, whereas Rm1021 and Rm8530 expA did not. These differences could be due to Rm8530's ability to produce EPS II. Survival experiments under saline stress showed that viability was reduced for Rm1021 but not for Rm8530 or Rm8530 expA, which suggests the existence of some regulating mechanism dependent on a functional expR that is absent in Rm1021. The results of salinity-induced stress assays regarding biofilm-forming capacity (BFC) and autoaggregation indicated the protective role of EPS II. As a whole, our observations demonstrate that EPS play major roles in rhizobacterial survival.
Collapse
Affiliation(s)
| | | | | | | | | | - Walter Giordano
- Instituto de Biotecnología Ambiental y Salud (INBIAS), CONICET, Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto (UNRC), Río Cuarto X5804BYA, Córdoba, Argentina; (E.P.); (P.B.); (S.C.); (E.F.); (F.N.)
| |
Collapse
|
20
|
Gene expression abundance dictated exopolysaccharide modification in Rhizobium radiobacter SZ4S7S14 as the cell's response to salt stress. Int J Biol Macromol 2020; 164:4339-4347. [PMID: 32931833 DOI: 10.1016/j.ijbiomac.2020.09.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 08/25/2020] [Accepted: 09/07/2020] [Indexed: 12/24/2022]
Abstract
A molecular and metabolic behaviour of EPS-producing and salt-tolerant bacterium Rhizobium radiobacter SZ4S7S14 along with its practical application in salt-stress was investigated. The research target was identification and expression profiles of a large EPS biosynthesis gene cluster, possible structural modification of EPS under salt-stress effect and analysis of the gene(s) relative expression and structural modification correlation. As expected, transposons insertions were identified within or near the coding regions of exoK and exoM, previously known large gene cluster that is required for EPS I synthesis. Different expression levels of exoK and exoM in different salt-stress models resulted in structural modification of EPS, which was seen basically in monomers molar ratio. As a result of downregulation of the genes the strain produced EPS samples with monomers ratio: (1) Glu:Man:Gal:Xyl:Ara:Rha:Rib = 31.21:3.02:2.77:1:0.91:0.64:0.41 (in 0.25% NaCl); (2) Glu:Man:Gal:Xyl:Ara:Rha:Rib = 7.65:1:0.69:0.22:0.2:0.16:0.1 (in 0.5% NaCl); (3) Glu:Man:Gal:Ara:Xyl:Rha:Rib = 9.39:1.89:1:0.58:0.52:0.46:0.26 (in 1% NaCl); and (4) Glu:Man:Ara:Xyl:Rib:Gal = 7.9:2:2:1.58:1.1:1 (in 2.0% NaCl), whereas in control (without NaCl): Glc:Man:Gal:Xyl:Ara:Rha:Rib = 11.66:1:0.90:0.37:0.37:0.15:0.14. It was found that, salt-stress not only leads to downregulation of a large EPS biosynthesis gene cluster, including exoK and exoM genes, but also impacting on their relative expression degree, re-groups of the monomers within the EPS matrix and dictates molar ratio of the monosaccharides in the final metabolite.
Collapse
|
21
|
Maillet F, Fournier J, Mendis HC, Tadege M, Wen J, Ratet P, Mysore KS, Gough C, Jones KM. Sinorhizobium meliloti succinylated high-molecular-weight succinoglycan and the Medicago truncatula LysM receptor-like kinase MtLYK10 participate independently in symbiotic infection. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 102:311-326. [PMID: 31782853 PMCID: PMC9327734 DOI: 10.1111/tpj.14625] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 11/08/2019] [Accepted: 11/19/2019] [Indexed: 05/12/2023]
Abstract
The formation of nitrogen-fixing nodules on legume hosts is a finely tuned process involving many components of both symbiotic partners. Production of the exopolysaccharide succinoglycan by the nitrogen-fixing bacterium Sinorhizobium meliloti 1021 is needed for an effective symbiosis with Medicago spp., and the succinyl modification to this polysaccharide is critical. However, it is not known when succinoglycan intervenes in the symbiotic process, and it is not known whether the plant lysin-motif receptor-like kinase MtLYK10 intervenes in recognition of succinoglycan, as might be inferred from work on the Lotus japonicus MtLYK10 ortholog, LjEPR3. We studied the symbiotic infection phenotypes of S. meliloti mutants deficient in succinoglycan production or producing modified succinoglycan, in wild-type Medicago truncatula plants and in Mtlyk10 mutant plants. On wild-type plants, S. meliloti strains producing no succinoglycan or only unsuccinylated succinoglycan still induced nodule primordia and epidermal infections, but further progression of the symbiotic process was blocked. These S. meliloti mutants induced a more severe infection phenotype on Mtlyk10 mutant plants. Nodulation by succinoglycan-defective strains was achieved by in trans rescue with a Nod factor-deficient S. meliloti mutant. While the Nod factor-deficient strain was always more abundant inside nodules, the succinoglycan-deficient strain was more efficient than the strain producing only unsuccinylated succinoglycan. Together, these data show that succinylated succinoglycan is essential for infection thread formation in M. truncatula, and that MtLYK10 plays an important, but different role in this symbiotic process. These data also suggest that succinoglycan is more important than Nod factors for bacterial survival inside nodules.
Collapse
Affiliation(s)
- Fabienne Maillet
- LIPMUniversité de Toulouse, INRA, CNRSCastanet‐TolosanCS 52627France
| | - Joëlle Fournier
- LIPMUniversité de Toulouse, INRA, CNRSCastanet‐TolosanCS 52627France
| | - Hajeewaka C. Mendis
- Department of Biological ScienceFlorida State UniversityTallahasseeFL32306USA
| | - Million Tadege
- Department of Plant and Soil SciencesInstitute for Agricultural BiosciencesOklahoma State UniversityArdmoreOK73401USA
| | - Jiangqi Wen
- Noble Research InstituteLLC.2510 Sam Noble ParkwayArdmoreOK73401USA
| | - Pascal Ratet
- IPS2Institute of Plant Sciences Paris-Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université Evry, Université Paris-SaclayBâtiment 63091405OrsayFrance
- Institute of Plant Sciences Paris-Saclay IPS2, Paris Diderot, Sorbonne Paris-CitéBâtiment 63091405OrsayFrance
| | | | - Clare Gough
- LIPMUniversité de Toulouse, INRA, CNRSCastanet‐TolosanCS 52627France
| | - Kathryn M. Jones
- Department of Biological ScienceFlorida State UniversityTallahasseeFL32306USA
| |
Collapse
|
22
|
Phylogenetics and antibacterial properties of exopolysaccharides from marine bacteria isolated from Mauritius seawater. ANN MICROBIOL 2019. [DOI: 10.1007/s13213-019-01487-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
|
23
|
Wippel K, Long SR. Symbiotic Performance of Sinorhizobium meliloti Lacking ppGpp Depends on the Medicago Host Species. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:717-728. [PMID: 30576265 DOI: 10.1094/mpmi-11-18-0306-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Host specificity in the root-nodule symbiosis between legumes and rhizobia is crucial for the establishment of a successful interaction and ammonia provision to the plant. The specificity is mediated by plant-bacterial signal exchange during early stages of interaction. We observed that a Sinorhizobium meliloti mutant ∆relA, which is deficient in initiating the bacterial stringent response, fails to nodulate Medicago sativa (alfalfa) but successfully infects Medicago truncatula. We used biochemical, histological, transcriptomic, and imaging approaches to compare the behavior of the S. meliloti ∆relA mutant and wild type (WT) on the two plant hosts. ∆relA performed almost WT-like on M. truncatula, except for reduced nitrogen-fixation capacity and a disorganized positioning of bacteroids within nodule cells. In contrast, ∆relA showed impaired root colonization on alfalfa and failed to infect nodule primordia. Global transcriptome analyses of ∆relA cells treated with the alfalfa flavonoid luteolin and of mature nodules induced by the mutant on M. truncatula revealed normal nod gene expression but overexpression of exopolysaccharide biosynthesis genes and a slight suppression of plant defense-like reactions. Many RelA-dependent transcripts overlap with the hypo-osmolarity-related FeuP regulon or are characteristic of stress responses. Based on our findings, we suggest that RelA is not essential until the late stages of symbiosis with M. truncatula, in which it may be involved in processes that optimize nitrogen fixation.
Collapse
Affiliation(s)
- Kathrin Wippel
- Department of Biology, Stanford University, Stanford, CA 94305, U.S.A
| | - Sharon R Long
- Department of Biology, Stanford University, Stanford, CA 94305, U.S.A
| |
Collapse
|
24
|
Wang J, Goh KM, Salem DR, Sani RK. Genome analysis of a thermophilic exopolysaccharide-producing bacterium - Geobacillus sp. WSUCF1. Sci Rep 2019; 9:1608. [PMID: 30733471 PMCID: PMC6367360 DOI: 10.1038/s41598-018-36983-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 11/16/2018] [Indexed: 11/23/2022] Open
Abstract
Geobacillus sp. WSUCF1 is a Gram-positive, spore-forming, aerobic and thermophilic bacterium, isolated from a soil sample obtained from a compost facility. Strain WSUCF1 demonstrated EPS producing capability using different sugars as the carbon source. The whole-genome analysis of WSUCF1 was performed to disclose the essential genes correlated with nucleotide sugar precursor biosynthesis, assembly of monosaccharide units, export of the polysaccharide chain, and regulation of EPS production. Both the biosynthesis pathway and export mechanism of EPS were proposed based on functional annotation. Additionally, the genome description of strain WSUCF1 suggests sophisticated systems for its adaptation under thermophilic conditions. The presence of genes associated with CRISPR-Cas system, quorum quenching lactonase, polyketide synthesis and arsenic resistance makes this strain a potential candidate for various applications in biotechnology and biomedicine. The present study indicates that strain WSUCF1 has promise as a thermophilic EPS producer for a broad range of industrial applications. To the best of our knowledge, this is the first report on genome analysis of a thermophilic Geobacillus species focusing on its EPS biosynthesis and transportation, which will likely pave the way for both enhanced yield and tailor-made EPS production by thermophilic bacteria.
Collapse
Affiliation(s)
- Jia Wang
- Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, SD, 57701, USA
- BuG ReMeDEE Consortium, South Dakota School of Mines and Technology, Rapid City, SD, 57701, USA
| | - Kian Mau Goh
- Faculty of Science, Universiti Teknologi Malaysia, Skudai, Johor, 81300, Malaysia
| | - David R Salem
- Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, SD, 57701, USA.
- Department of Materials and Metallurgical Engineering, South Dakota School of Mines and Technology, Rapid City, SD, 57701, USA.
- Composite and Nanocomposite Advanced Manufacturing - Biomaterials Center (CNAM-Bio Center), Rapid City, SD, 57701, USA.
| | - Rajesh K Sani
- Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, SD, 57701, USA.
- Composite and Nanocomposite Advanced Manufacturing - Biomaterials Center (CNAM-Bio Center), Rapid City, SD, 57701, USA.
- BuG ReMeDEE Consortium, South Dakota School of Mines and Technology, Rapid City, SD, 57701, USA.
| |
Collapse
|
25
|
Extremophilic exopolysaccharides: A review and new perspectives on engineering strategies and applications. Carbohydr Polym 2019; 205:8-26. [DOI: 10.1016/j.carbpol.2018.10.011] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 09/20/2018] [Accepted: 10/04/2018] [Indexed: 12/16/2022]
|
26
|
Stambulska UY, Bayliak MM. Legume-Rhizobium Symbiosis: Secondary Metabolites, Free Radical Processes, and Effects of Heavy Metals. BIOACTIVE MOLECULES IN FOOD 2019. [DOI: 10.1007/978-3-319-76887-8_43-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
27
|
Xu YY, Yang JS, Liu C, Wang ET, Wang RN, Qiu XQ, Li BZ, Chen WF, Yuan HL. Water-Soluble Humic Materials Regulate Quorum Sensing in Sinorhizobium meliloti Through a Novel Repressor of expR. Front Microbiol 2018; 9:3194. [PMID: 30627123 PMCID: PMC6309736 DOI: 10.3389/fmicb.2018.03194] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 12/10/2018] [Indexed: 11/23/2022] Open
Abstract
Quorum sensing (QS) plays an important role in the growth, nodulation, and nitrogen fixation of rhizobia. In this study, we show that water-soluble humic materials (WSHM) repress the expression of the QS related genes sinI, sinR, and expR in Sinorhizobium meliloti. This decreased the production of N-acetyl homoserine lactones (AHL) and exopolysaccharides (EPS), and ultimately increased S. meliloti cell density. We also identified a novel regulator, SMc03890 (renamed QsrR), which binds directly to the expR promoter. Deletion of qsrR increased expR expression. WSHM repressed the expression of expR by augmenting the interaction between QsrR and the expR promoter; this was determined by a bacterial-one-hybrid assay. These effects of WSHM on the QS system in S. meliloti may be the underlying mechanism by which WSHM increase the symbiotic nitrogen fixation of Medicago sativa inoculated with S. meliloti. This study provides the first evidence that humic acids regulate the QS of rhizobia and suggests that WSHM could be used as fertilizers to improve the efficiency of symbiotic nitrogen fixation.
Collapse
Affiliation(s)
- Yuan-Yuan Xu
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Jin-Shui Yang
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Cong Liu
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - En-Tao Wang
- Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Ruo-Nan Wang
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xiao-Qian Qiu
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Bao-Zhen Li
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Wen-Feng Chen
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Hong-Li Yuan
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| |
Collapse
|
28
|
Ratib NR, Sabio EY, Mendoza C, Barnett MJ, Clover SB, Ortega JA, Dela Cruz FM, Balderas D, White H, Long SR, Chen EJ. Genome-wide identification of genes directly regulated by ChvI and a consensus sequence for ChvI binding in Sinorhizobium meliloti. Mol Microbiol 2018; 110:596-615. [PMID: 30192418 DOI: 10.1111/mmi.14119] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Revised: 08/16/2018] [Accepted: 09/04/2018] [Indexed: 12/11/2022]
Abstract
ExoS/ChvI two-component signaling in the nitrogen-fixing α-proteobacterium Sinorhizobium meliloti is required for symbiosis and regulates exopolysaccharide production, motility, cell envelope integrity and nutrient utilization in free-living bacteria. However, identification of many ExoS/ChvI direct transcriptional target genes has remained elusive. Here, we performed chromatin immunoprecipitation followed by microarray analysis (chIP-chip) to globally identify DNA regions bound by ChvI protein in S. meliloti. We then performed qRT-PCR with chvI mutant strains to test ChvI-dependent expression of genes downstream of the ChvI-bound DNA regions. We identified 64 direct target genes of ChvI, including exoY, rem and chvI itself. We also identified ChvI direct target candidates, like exoR, that are likely controlled by additional regulators. Analysis of upstream sequences from the 64 ChvI direct target genes identified a 15 bp-long consensus sequence. Using electrophoretic mobility shift assays and transcriptional fusions with exoY, SMb21440, SMc00084, SMc01580, chvI, and ropB1, we demonstrated this consensus sequence is important for ChvI binding to DNA and transcription of ChvI direct target genes. Thus, we have comprehensively identified ChvI regulon genes and a 'ChvI box' bound by ChvI. Many ChvI direct target genes may influence the cell envelope, consistent with the critical role of ExoS/ChvI in growth and microbe-host interactions.
Collapse
Affiliation(s)
- Nicole R Ratib
- Department of Biological Science, Center for Applied Biotechnology Studies, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA, USA
| | - Erich Y Sabio
- Department of Biological Science, Center for Applied Biotechnology Studies, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA, USA
| | - Carolina Mendoza
- Department of Biological Science, Center for Applied Biotechnology Studies, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA, USA
| | | | - Sarah B Clover
- Department of Biological Science, Center for Applied Biotechnology Studies, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA, USA
| | - Jesus A Ortega
- Department of Biological Science, Center for Applied Biotechnology Studies, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA, USA
| | - Francesca M Dela Cruz
- Department of Biological Science, Center for Applied Biotechnology Studies, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA, USA
| | - David Balderas
- Department of Biological Science, Center for Applied Biotechnology Studies, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA, USA
| | - Holly White
- Department of Biological Science, Center for Applied Biotechnology Studies, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA, USA
| | - Sharon R Long
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Esther J Chen
- Department of Biological Science, Center for Applied Biotechnology Studies, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA, USA
| |
Collapse
|
29
|
Dai X, Gao G, Wu M, Wei W, Qu J, Li G, Ma T. Construction and application of a Xanthomonas campestris CGMCC15155 strain that produces white xanthan gum. Microbiologyopen 2018; 8:e00631. [PMID: 29656507 PMCID: PMC6391268 DOI: 10.1002/mbo3.631] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Revised: 01/19/2018] [Accepted: 02/28/2018] [Indexed: 11/14/2022] Open
Abstract
In the industrial production of xanthan gum using Xanthomonas campestris CGMCC15155, large amounts of ethanol are required to extract xanthan gum from the fermentation broth and remove xanthomonadin impurities. To reduce the amount of ethanol and the overall production cost of xanthan gum, a xanthomonadin‐deficient strain of CGMCC15155 was constructed by inserting the Vitreoscilla globin (vgb) gene, under the control of the LacZ promoter, into the region of the pigA gene, which is involved in xanthomonadin synthesis. The insertion of vgb inactivated pigA, resulting in the production of white xanthan gum. The lack of xanthomonadins resulted in a decreased yield of xanthan gum. However, the expression product of vgb gene, VHb, could increase the metabolism of X. campestris, which allowed the production of xanthan gum to reach wild‐type levels in the engineered strain. The yield, molecular weight, and rheological properties of the xanthan gum synthesized by the engineered and wild‐type bacteria were essentially the same. When the same volume of ethanol was used, the whiteness values of the xanthan gum extracted from engineered and wild‐type bacteria were 65.20 and 38.17, respectively. To extract xanthan gum with the same whiteness, three and seven times the fermentation volume of ethanol was required for the engineered and wild‐type strains, respectively. Thus, the engineered train reduced the requirement for ethanol in xanthan gum production by 133.3%. The results demonstrated that the engineered bacteria used less ethanol, thus reducing the downstream processing cost in xanthan gum production.
Collapse
Affiliation(s)
- Xiaohui Dai
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Ge Gao
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Mengmeng Wu
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Weiying Wei
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Jianmei Qu
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Guoqiang Li
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China.,Tianjin Engineering Technology Center of Green Manufacturing Biobased Materials, Tianjin, China
| | - Ting Ma
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China.,Tianjin Engineering Technology Center of Green Manufacturing Biobased Materials, Tianjin, China
| |
Collapse
|
30
|
Sengupta D, Datta S, Biswas D. Towards a better production of bacterial exopolysaccharides by controlling genetic as well as physico-chemical parameters. Appl Microbiol Biotechnol 2018; 102:1587-1598. [DOI: 10.1007/s00253-018-8745-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 12/22/2017] [Accepted: 12/27/2017] [Indexed: 11/28/2022]
|
31
|
Wang Q, Liu J, Zhu H. Genetic and Molecular Mechanisms Underlying Symbiotic Specificity in Legume-Rhizobium Interactions. FRONTIERS IN PLANT SCIENCE 2018; 9:313. [PMID: 29593768 PMCID: PMC5854654 DOI: 10.3389/fpls.2018.00313] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 02/23/2018] [Indexed: 05/20/2023]
Abstract
Legumes are able to form a symbiotic relationship with nitrogen-fixing soil bacteria called rhizobia. The result of this symbiosis is to form nodules on the plant root, within which the bacteria can convert atmospheric nitrogen into ammonia that can be used by the plant. Establishment of a successful symbiosis requires the two symbiotic partners to be compatible with each other throughout the process of symbiotic development. However, incompatibility frequently occurs, such that a bacterial strain is unable to nodulate a particular host plant or forms nodules that are incapable of fixing nitrogen. Genetic and molecular mechanisms that regulate symbiotic specificity are diverse, involving a wide range of host and bacterial genes/signals with various modes of action. In this review, we will provide an update on our current knowledge of how the recognition specificity has evolved in the context of symbiosis signaling and plant immunity.
Collapse
|
32
|
Marczak M, Mazur A, Koper P, Żebracki K, Skorupska A. Synthesis of Rhizobial Exopolysaccharides and Their Importance for Symbiosis with Legume Plants. Genes (Basel) 2017; 8:E360. [PMID: 29194398 PMCID: PMC5748678 DOI: 10.3390/genes8120360] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 11/26/2017] [Accepted: 11/29/2017] [Indexed: 12/25/2022] Open
Abstract
Rhizobia dwell and multiply in the soil and represent a unique group of bacteria able to enter into a symbiotic interaction with plants from the Fabaceae family and fix atmospheric nitrogen inside de novo created plant organs, called nodules. One of the key determinants of the successful interaction between these bacteria and plants are exopolysaccharides, which represent species-specific homo- and heteropolymers of different carbohydrate units frequently decorated by non-carbohydrate substituents. Exopolysaccharides are typically built from repeat units assembled by the Wzx/Wzy-dependent pathway, where individual subunits are synthesized in conjunction with the lipid anchor undecaprenylphosphate (und-PP), due to the activity of glycosyltransferases. Complete oligosaccharide repeat units are transferred to the periplasmic space by the activity of the Wzx flippase, and, while still being anchored in the membrane, they are joined by the polymerase Wzy. Here we have focused on the genetic control over the process of exopolysaccharides (EPS) biosynthesis in rhizobia, with emphasis put on the recent advancements in understanding the mode of action of the key proteins operating in the pathway. A role played by exopolysaccharide in Rhizobium-legume symbiosis, including recent data confirming the signaling function of EPS, is also discussed.
Collapse
Affiliation(s)
- Małgorzata Marczak
- Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
| | - Andrzej Mazur
- Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
| | - Piotr Koper
- Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
| | - Kamil Żebracki
- Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
| | - Anna Skorupska
- Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
| |
Collapse
|
33
|
Hawkins JP, Geddes BA, Oresnik IJ. Succinoglycan Production Contributes to Acidic pH Tolerance in Sinorhizobium meliloti Rm1021. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2017; 30:1009-1019. [PMID: 28871850 DOI: 10.1094/mpmi-07-17-0176-r] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this work, the hypothesis that exopolysaccharide plays a role in the survival of Sinorhizobium meliloti at low pH levels is addressed. When S. meliloti was grown at pH 5.75, synthesis of succinoglycan increased, whereas synthesis of galactoglucan decreased. Succinoglycan that was isolated from cultures grown at low pH had a lower degree of polymerization relative to that which was isolated from cultures grown at neutral pH, suggesting that low-molecular weight (LMW) succinoglycan might play a role in adaptation to low pH. Mutants unable to produce succinoglycan or only able to produce high-molecular weight polysaccharide were found to be sensitive to low pH. However, strains unable to produce LMW polysaccharide were 10-fold more sensitive. In response to low pH, transcription of genes encoding proteins for succinoglycan, glycogen, and cyclic β(1-2) glucans biosynthesis increased, while those encoding proteins necessary for the biosynthesis of galactoglucan decreased. While changes in pH did not affect the production of glycogen or cyclic β(1-2) glucan, it was found that the inability to produce cyclic β(1-2) glucan did contribute to pH tolerance in the absence of succinoglycan. Finally, in addition to being sensitive to low pH, a strain carrying mutations in exoK and exsH, which encode the glycanases responsible for the cleavage of succinoglycan to LMW succinoglycan, exhibited a delay in nodulation and was uncompetitive for nodule occupancy. Taken together, the data suggest that the role for LMW succinoglycan in nodule development may be to enhance survival in the colonized curled root hair.
Collapse
Affiliation(s)
- Justin P Hawkins
- Dept. of Microbiology, University of Manitoba, Winnipeg, R3T 2N2, Canada
| | - Barney A Geddes
- Dept. of Microbiology, University of Manitoba, Winnipeg, R3T 2N2, Canada
| | - Ivan J Oresnik
- Dept. of Microbiology, University of Manitoba, Winnipeg, R3T 2N2, Canada
| |
Collapse
|
34
|
Zou L, Gastebois A, Mathieu-Demazière C, Sorroche F, Masson-Boivin C, Batut J, Garnerone AM. Transcriptomic Insight in the Control of Legume Root Secondary Infection by the Sinorhizobium meliloti Transcriptional Regulator Clr. Front Microbiol 2017; 8:1236. [PMID: 28729859 PMCID: PMC5498481 DOI: 10.3389/fmicb.2017.01236] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 06/19/2017] [Indexed: 12/02/2022] Open
Abstract
The cAMP-dependent transcriptional regulator Clr of Sinorhizobium meliloti regulates the overall number of infection events on Medicago roots by a so-far unknown mechanism requiring smc02178, a Clr-target gene of unknown function. In order to shed light on the mode of action of Clr on infection and potentially reveal additional biological functions for Clr, we inventoried genomic Clr target genes by transcriptome profiling. We have found that Clr positively controls the synthesis of cAMP-dependent succinoglycan as well as the expression of genes involved in the synthesis of a so-far unknown polysaccharide compound. In addition, Clr activated expression of 24 genes of unknown function in addition to smc02178. Genes negatively controlled by Clr were mainly involved in swimming motility and chemotaxis. Functional characterization of two novel Clr-activated genes of unknown function, smb20495 and smc02177, showed that their expression was activated by the same plant signal as smc02178 ex planta. In planta, however, symbiotic expression of smc02177 proved independent of clr. Both smc02177 and smb20495 genes were strictly required for the control of secondary infection on M. sativa. None of the three smc02177, smc02178 and smb20495 genes were needed for plant signal perception. Altogether this work provides a refined view of the cAMP-dependent Clr regulon of S. meliloti. We specifically discuss the possible roles of smc02177, smc02178, smb20495 genes and other Clr-controlled genes in the control of secondary infection of Medicago roots.
Collapse
Affiliation(s)
- Lan Zou
- LIPM, Université de Toulouse, INRA, CNRSCastanet-Tolosan, France
| | | | | | | | | | - Jacques Batut
- LIPM, Université de Toulouse, INRA, CNRSCastanet-Tolosan, France
| | | |
Collapse
|
35
|
Kazmierczak T, Nagymihály M, Lamouche F, Barrière Q, Guefrachi I, Alunni B, Ouadghiri M, Ibijbijen J, Kondorosi É, Mergaert P, Gruber V. Specific Host-Responsive Associations Between Medicago truncatula Accessions and Sinorhizobium Strains. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2017; 30:399-409. [PMID: 28437159 DOI: 10.1094/mpmi-01-17-0009-r] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Legume plants interact with rhizobia to form nitrogen-fixing root nodules. Legume-rhizobium interactions are specific and only compatible rhizobia and plant species will lead to nodule formation. Even within compatible interactions, the genotype of both the plant and the bacterial symbiont will impact on the efficiency of nodule functioning and nitrogen-fixation activity. The model legume Medicago truncatula forms nodules with several species of the Sinorhizobium genus. However, the efficiency of these bacterial strains is highly variable. In this study, we compared the symbiotic efficiency of Sinorhizobium meliloti strains Sm1021, 102F34, and FSM-MA, and Sinorhizobium medicae strain WSM419 on the two widely used M. truncatula accessions A17 and R108. The efficiency of the interactions was determined by multiple parameters. We found a high effectiveness of the FSM-MA strain with both M. truncatula accessions. In contrast, specific highly efficient interactions were obtained for the A17-WSM419 and R108-102F34 combinations. Remarkably, the widely used Sm1021 strain performed weakly on both hosts. We showed that Sm1021 efficiently induced nodule organogenesis but cannot fully activate the differentiation of the symbiotic nodule cells, explaining its weaker performance. These results will be informative for the selection of appropriate rhizobium strains in functional studies on symbiosis using these M. truncatula accessions, particularly for research focusing on late stages of the nodulation process.
Collapse
Affiliation(s)
- Théophile Kazmierczak
- 1 Institute of Plant Sciences Paris Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université Evry, Université Paris-Saclay, Bâtiment 630, 91405 Orsay, France. Institute of Plant Sciences Paris-Saclay IPS2, Université Paris Diderot, Sorbonne Paris-Cité, Bâtiment 630, 91405, Orsay, France
| | - Marianna Nagymihály
- 2 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, 91198, Gif-sur-Yvette, France
- 3 Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, 6726 Szeged, Hungary
| | - Florian Lamouche
- 2 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, 91198, Gif-sur-Yvette, France
| | - Quentin Barrière
- 2 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, 91198, Gif-sur-Yvette, France
| | - Ibtissem Guefrachi
- 2 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, 91198, Gif-sur-Yvette, France
| | - Benoit Alunni
- 2 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, 91198, Gif-sur-Yvette, France
| | - Mouna Ouadghiri
- 4 Collections Coordonnées Marocaines de Microorganismes et Laboratoire de Microbiologie et Biologie Moléculaire, Centre National pour la Recherche Scientifique et Technique, Rabat, Maroc; and
| | - Jamal Ibijbijen
- 5 Faculté des Sciences, Université Moulay Ismail, Meknès, Maroc, Faculté des Sciences, Université Moulay Ismail, BP 11201 Zitoune, Meknès, Maroc
| | - Éva Kondorosi
- 2 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, 91198, Gif-sur-Yvette, France
- 3 Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, 6726 Szeged, Hungary
| | - Peter Mergaert
- 2 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, 91198, Gif-sur-Yvette, France
| | - Véronique Gruber
- 1 Institute of Plant Sciences Paris Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université Evry, Université Paris-Saclay, Bâtiment 630, 91405 Orsay, France. Institute of Plant Sciences Paris-Saclay IPS2, Université Paris Diderot, Sorbonne Paris-Cité, Bâtiment 630, 91405, Orsay, France
| |
Collapse
|
36
|
Hawkins JP, Oresnik IJ. Characterisation of a gene encoding a membrane protein that affects exopolysaccharide production and intracellular Mg2+ concentrations in Ensifer meliloti. FEMS Microbiol Lett 2017; 364:3072829. [DOI: 10.1093/femsle/fnx061] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 03/15/2017] [Indexed: 12/30/2022] Open
|
37
|
Firsova YE, Torgonskaya ML, Trotsenko YA. Functionality of Metdi5511gene in Methylobacterium dichloromethanicum DM4. APPL BIOCHEM MICRO+ 2017. [DOI: 10.1134/s0003683817020089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
38
|
Nett RS, Montanares M, Marcassa A, Lu X, Nagel R, Charles TC, Hedden P, Rojas MC, Peters RJ. Elucidation of gibberellin biosynthesis in bacteria reveals convergent evolution. Nat Chem Biol 2016; 13:69-74. [PMID: 27842068 DOI: 10.1038/nchembio.2232] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Accepted: 09/23/2016] [Indexed: 12/22/2022]
Abstract
Gibberellins (GAs) are crucial phytohormones involved in many aspects of plant growth and development, including plant-microbe interactions, which has led to GA production by plant-associated fungi and bacteria as well. While the GA biosynthetic pathways in plants and fungi have been elucidated and found to have arisen independently through convergent evolution, little has been uncovered about GA biosynthesis in bacteria. Some nitrogen-fixing, symbiotic, legume-associated rhizobia, including Bradyrhizobium japonicum-the symbiont of soybean-and Sinorhizobium fredii-a broad-host-nodulating species-contain a putative GA biosynthetic operon, or gene cluster. Through functional characterization of five unknown genes, we demonstrate that this operon encodes the enzymes necessary to produce GA9, thereby elucidating bacterial GA biosynthesis. The distinct nature of these enzymes indicates that bacteria have independently evolved a third biosynthetic pathway for GA production. Furthermore, our results also reveal a central biochemical logic that is followed in all three convergently evolved GA biosynthetic pathways.
Collapse
Affiliation(s)
- Ryan S Nett
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa, USA
| | - Mariana Montanares
- Laboratorio de Bioorgánica, Departamento de Química, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Ariana Marcassa
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Xuan Lu
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa, USA
| | - Raimund Nagel
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa, USA
| | - Trevor C Charles
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Peter Hedden
- Rothamsted Research, Harpenden, Hertfordshire, UK
| | - Maria Cecilia Rojas
- Laboratorio de Bioorgánica, Departamento de Química, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Reuben J Peters
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa, USA
| |
Collapse
|
39
|
Function of Succinoglycan Polysaccharide in Sinorhizobium meliloti Host Plant Invasion Depends on Succinylation, Not Molecular Weight. mBio 2016; 7:mBio.00606-16. [PMID: 27329751 PMCID: PMC4916376 DOI: 10.1128/mbio.00606-16] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The acidic polysaccharide succinoglycan produced by the rhizobial symbiont Sinorhizobium meliloti 1021 is required for this bacterium to invade the host plant Medicago truncatula and establish a nitrogen-fixing symbiosis. S. meliloti mutants that cannot make succinoglycan cannot initiate invasion structures called infection threads in plant root hairs. S. meliloti exoH mutants that cannot succinylate succinoglycan are also unable to form infection threads, despite the fact that they make large quantities of succinoglycan. Succinoglycan produced by exoH mutants is refractory to cleavage by the glycanases encoded by exoK and exsH, and thus succinoglycan produced by exoH mutants is made only in the high-molecular-weight (HMW) form. One interpretation of the symbiotic defect of exoH mutants is that the low-molecular-weight (LMW) form of succinoglycan is required for infection thread formation. However, our data demonstrate that production of the HMW form of succinoglycan by S. meliloti 1021 is sufficient for invasion of the host M. truncatula and that the LMW form is not required. Here, we show that S. meliloti strains deficient in the exoK- and exsH-encoded glycanases invade M. truncatula and form a productive symbiosis, although they do this with somewhat less efficiency than the wild type. We have also characterized the polysaccharides produced by these double glycanase mutants and determined that they consist of only HMW succinoglycan and no detectable LMW succinoglycan. This demonstrates that LMW succinoglycan is not required for host invasion. These results suggest succinoglycan function is not dependent upon the presence of a small, readily diffusible form. Sinorhizobium meliloti is a bacterium that forms a beneficial symbiosis with legume host plants. S. meliloti and other rhizobia convert atmospheric nitrogen to ammonia, a nutrient source for the host plant. To establish the symbiosis, rhizobia must invade plant roots, supplying the proper signals to prevent a plant immune response during invasion. A polysaccharide, succinoglycan, produced by S. meliloti is required for successful invasion. Here, we show that the critical feature of succinoglycan that allows infection to proceed is the attachment of a “succinyl” chemical group and that the chain length of succinoglycan is much less important for its function. We also show that none of the short-chain versions of succinoglycan is produced in the absence of two chain-cleaving enzymes.
Collapse
|
40
|
Medeot DB, Romina Rivero M, Cendoya E, Contreras-Moreira B, Rossi FA, Fischer SE, Becker A, Jofré E. Sinorhizobium meliloti low molecular mass phosphotyrosine phosphatase SMc02309 modifies activity of the UDP-glucose pyrophosphorylase ExoN involved in succinoglycan biosynthesis. MICROBIOLOGY-SGM 2016; 162:552-563. [PMID: 26813656 DOI: 10.1099/mic.0.000239] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In Gram-negative bacteria, tyrosine phosphorylation has been shown to play a role in the control of exopolysaccharide (EPS) production. This study demonstrated that the chromosomal ORF SMc02309 from Sinorhizobium meliloti 2011 encodes a protein with significant sequence similarity to low molecular mass protein-tyrosine phosphatases (LMW-PTPs), such as the Escherichia coli Wzb. Unlike other well-characterized EPS biosynthesis gene clusters, which contain neighbouring LMW-PTPs and kinase, the S. meliloti succinoglycan (EPS I) gene cluster located on megaplasmid pSymB does not encode a phosphatase. Biochemical assays revealed that the SMc02309 protein hydrolyses p-nitrophenyl phosphate (p-NPP) with kinetic parameters similar to other bacterial LMW-PTPs. Furthermore, we show evidence that SMc02309 is not the LMW-PTP of the bacterial tyrosine-kinase (BY-kinase) ExoP. Nevertheless, ExoN, a UDP-glucose pyrophosphorylase involved in the first stages of EPS I biosynthesis, is phosphorylated at tyrosine residues and constitutes an endogenous substrate of the SMc02309 protein. Additionally, we show that the UDP-glucose pyrophosphorylase activity is modulated by SMc02309-mediated tyrosine dephosphorylation. Moreover, a mutation in the SMc02309 gene decreases EPS I production and delays nodulation on Medicago sativa roots.
Collapse
Affiliation(s)
- Daniela B Medeot
- Department of Natural Sciences, FCEFQyN, National University of Río Cuarto, Ruta Nacional 36 Km 601, Córdoba, Argentina
- Department of Molecular Biology, FCEFQyN, National University of Río Cuarto, Ruta Nacional 36 Km 601, Córdoba, Argentina
| | - María Romina Rivero
- Department of Natural Sciences, FCEFQyN, National University of Río Cuarto, Ruta Nacional 36 Km 601, Córdoba, Argentina
| | - Eugenia Cendoya
- Department of Natural Sciences, FCEFQyN, National University of Río Cuarto, Ruta Nacional 36 Km 601, Córdoba, Argentina
| | - Bruno Contreras-Moreira
- Laboratory of Computational Biology, Department of Genetics and Plant Production, Estación Experimental de Aula Dei/CSIC, Av. Montañana 1005, Zaragoza, Spain
| | - Fernando A Rossi
- Department of Natural Sciences, FCEFQyN, National University of Río Cuarto, Ruta Nacional 36 Km 601, Córdoba, Argentina
| | - Sonia E Fischer
- Department of Natural Sciences, FCEFQyN, National University of Río Cuarto, Ruta Nacional 36 Km 601, Córdoba, Argentina
| | - Anke Becker
- LOEWE-Center for Synthetic Microbiology, Philipps-Universität Marburg, D-35032, Marburg, Germany
| | - Edgardo Jofré
- Department of Natural Sciences, FCEFQyN, National University of Río Cuarto, Ruta Nacional 36 Km 601, Córdoba, Argentina
| |
Collapse
|
41
|
Chen R. The sweet branch of metabolic engineering: cherry-picking the low-hanging sugary fruits. Microb Cell Fact 2015; 14:197. [PMID: 26655367 PMCID: PMC4674990 DOI: 10.1186/s12934-015-0389-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 11/25/2015] [Indexed: 02/08/2023] Open
Abstract
In the first science review on the then nascent Metabolic Engineering field in 1991, Dr. James E. Bailey described how improving erythropoietin (EPO) glycosylation can be achieved via metabolic engineering of Chinese hamster ovary (CHO) cells. In the intervening decades, metabolic engineering has brought sweet successes in glycoprotein engineering, including antibodies, vaccines, and other human therapeutics. Today, not only eukaryotes (CHO, plant, insect, yeast) are being used for manufacturing protein therapeutics with human-like glycosylation, newly elucidated bacterial glycosylation systems are enthusiastically embraced as potential breakthrough to revolutionize the biopharmaceutical industry. Notwithstanding these excitement in glycoprotein, the sweet metabolic engineering reaches far beyond glycoproteins. Many different types of oligo- and poly-saccharides are synthesized with metabolically engineered cells. For example, several recombinant hyaluronan bioprocesses are now in commercial production, and the titer of 2′-fucosyllactose, the most abundant fucosylated trisaccharide in human milk, reaches over 20 g/L with engineered E. coli cells. These successes represent only the first low hanging fruits, which have been appreciated scientifically, medically and fortunately, commercially as well. As one of the four building blocks of life, sugar molecules permeate almost all aspects of life. They are also unique in being intimately associated with all major types of biopolymers (including DNA/RNA, proteins, lipids) meanwhile they stand alone as bioactive polysaccharides, or free soluble oligosaccharides. As such, all sugar moieties in biological components, small or big and free or bound, are important targets for metabolic engineering. Opportunities abound at the interface of glycosciences and metabolic engineering. Continued investment and successes in this branch of metabolic engineering will make vastly diverse sugar-containing molecules (a.k.a. glycoconjugates) available for biomedical applications, sustainable technology development, and as invaluable tools for basic scientific research. This short review focuses on the most recent development in the field, with emphasis on the synthesis technology for glycoprotein, polysaccharide, and oligosaccharide.
Collapse
Affiliation(s)
- Rachel Chen
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, NW, Atlanta, GA, 30332-0100, USA.
| |
Collapse
|
42
|
Schmid J, Sieber V, Rehm B. Bacterial exopolysaccharides: biosynthesis pathways and engineering strategies. Front Microbiol 2015; 6:496. [PMID: 26074894 PMCID: PMC4443731 DOI: 10.3389/fmicb.2015.00496] [Citation(s) in RCA: 306] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 05/06/2015] [Indexed: 12/13/2022] Open
Abstract
Bacteria produce a wide range of exopolysaccharides which are synthesized via different biosynthesis pathways. The genes responsible for synthesis are often clustered within the genome of the respective production organism. A better understanding of the fundamental processes involved in exopolysaccharide biosynthesis and the regulation of these processes is critical toward genetic, metabolic and protein-engineering approaches to produce tailor-made polymers. These designer polymers will exhibit superior material properties targeting medical and industrial applications. Exploiting the natural design space for production of a variety of biopolymer will open up a range of new applications. Here, we summarize the key aspects of microbial exopolysaccharide biosynthesis and highlight the latest engineering approaches toward the production of tailor-made variants with the potential to be used as valuable renewable and high-performance products for medical and industrial applications.
Collapse
Affiliation(s)
- Jochen Schmid
- Chair of Chemistry of Biogenic Resources, Technische Universität MünchenStraubing, Germany
| | - Volker Sieber
- Chair of Chemistry of Biogenic Resources, Technische Universität MünchenStraubing, Germany
| | - Bernd Rehm
- Institute of Fundamental Sciences, Massey UniversityPalmerston North, New Zealand
- The MacDiarmid Institute for Advanced Materials and NanotechnologyPalmerston North, New Zealand
| |
Collapse
|
43
|
Rodríguez-Navarro DN, Rodríguez-Carvajal MA, Acosta-Jurado S, Soto MJ, Margaret I, Crespo-Rivas JC, Sanjuan J, Temprano F, Gil-Serrano A, Ruiz-Sainz JE, Vinardell JM. Structure and biological roles of Sinorhizobium fredii HH103 exopolysaccharide. PLoS One 2014; 9:e115391. [PMID: 25521500 PMCID: PMC4270759 DOI: 10.1371/journal.pone.0115391] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 11/21/2014] [Indexed: 11/25/2022] Open
Abstract
Here we report that the structure of the Sinorhizobium fredii HH103 exopolysaccharide (EPS) is composed of glucose, galactose, glucuronic acid, pyruvic acid, in the ratios 5∶2∶2∶1 and is partially acetylated. A S. fredii HH103 exoA mutant (SVQ530), unable to produce EPS, not only forms nitrogen fixing nodules with soybean but also shows increased competitive capacity for nodule occupancy. Mutant SVQ530 is, however, less competitive to nodulate Vigna unguiculata. Biofilm formation was reduced in mutant SVQ530 but increased in an EPS overproducing mutant. Mutant SVQ530 was impaired in surface motility and showed higher osmosensitivity compared to its wild type strain in media containing 50 mM NaCl or 5% (w/v) sucrose. Neither S. fredii HH103 nor 41 other S. fredii strains were recognized by soybean lectin (SBL). S. fredii HH103 mutants affected in exopolysaccharides (EPS), lipopolysaccharides (LPS), cyclic glucans (CG) or capsular polysaccharides (KPS) were not significantly impaired in their soybean-root attachment capacity, suggesting that these surface polysaccharides might not be relevant in early attachment to soybean roots. These results also indicate that the molecular mechanisms involved in S. fredii attachment to soybean roots might be different to those operating in Bradyrhizobium japonicum.
Collapse
Affiliation(s)
| | | | | | - María J Soto
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, Granada, Spain
| | - Isabel Margaret
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain
| | - Juan C Crespo-Rivas
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain
| | - Juan Sanjuan
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, Granada, Spain
| | - Francisco Temprano
- IFAPA, Centro las Torres-Tomejil, Apartado Oficial 41200, Alcalá del Río, (Sevilla), Spain
| | - Antonio Gil-Serrano
- Departamento de Química Orgánica, Facultad de Química, Universidad de Sevilla, Sevilla, Spain
| | - José E Ruiz-Sainz
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain
| | - José M Vinardell
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain
| |
Collapse
|
44
|
Geddes BA, González JE, Oresnik IJ. Exopolysaccharide production in response to medium acidification is correlated with an increase in competition for nodule occupancy. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:1307-17. [PMID: 25387133 DOI: 10.1094/mpmi-06-14-0168-r] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Sinorhizobium meliloti strains unable to utilize galactose as a sole carbon source, due to mutations in the De-Ley Doudoroff pathway (dgoK), were previously shown to be more competitive for nodule occupancy. In this work, we show that strains carrying this mutation have galactose-dependent exopolysaccharide (EPS) phenotypes that were manifested as aberrant Calcofluor staining as well as decreased mucoidy when in an expR(+) genetic background. The aberrant Calcofluor staining was correlated with changes in the pH of the growth medium. Strains carrying dgoK mutations were subsequently demonstrated to show earlier acidification of their growth medium that was correlated with an increase expression of genes associated with succinoglycan biosynthesis as well as increased accumulation of high and low molecular weight EPS in the medium. In addition, it was shown that the acidification of the medium was dependent on the inability of S. meliloti strains to initiate the catabolism of galactose. To more fully understand why strains carrying the dgoK allele were more competitive for nodule occupancy, early nodulation phenotypes were investigated. It was found that strains carrying the dgoK allele had a faster rate of nodulation. In addition, nodule competition experiments using genetic backgrounds unable to synthesize either succinoglycan or EPSII were consistent with the hypothesis that the increased competition phenotype was dependent upon the synthesis of succinoglycan. Fluorescent microscopy experiments on infected root-hair cells, using the acidotropic dye Lysotracker Red DND-99, provide evidence that the colonized curled root hair is an acidic compartment.
Collapse
|
45
|
ExpR coordinates the expression of symbiotically important, bundle-forming Flp pili with quorum sensing in Sinorhizobium meliloti. Appl Environ Microbiol 2014; 80:2429-39. [PMID: 24509921 DOI: 10.1128/aem.04088-13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Type IVb pili in enteropathogenic bacteria function as a host colonization factor by mediating tight adherence to host cells, but their role in bacterium-plant symbiosis is currently unknown. The genome of the symbiotic soil bacterium Sinorhizobium meliloti contains two clusters encoding proteins for type IVb pili of the Flp (fimbrial low-molecular-weight protein) subfamily. To establish the role of Flp pili in the symbiotic interaction of S. meliloti and its host, Medicago sativa, we deleted pilA1, which encodes the putative pilin subunit in the chromosomal flp-1 cluster and conducted competitive nodulation assays. The pilA1 deletion strain formed 27% fewer nodules than the wild type. Transmission electron microscopy revealed the presence of bundle-forming pili protruding from the polar and lateral region of S. meliloti wild-type cells. The putative pilus assembly ATPase CpaE1 fused to mCherry showed a predominantly unilateral localization. Transcriptional reporter gene assays demonstrated that expression of pilA1 peaks in early stationary phase and is repressed by the quorum-sensing regulator ExpR, which also controls production of exopolysaccharides and motility. Binding of acyl homoserine lactone-activated ExpR to the pilA1 promoter was confirmed with electrophoretic mobility shift assays. A 17-bp consensus sequence for ExpR binding was identified within the 28-bp protected region by DNase I footprinting analyses. Our results show that Flp pili are important for efficient symbiosis of S. meliloti with its plant host. The temporal inverse regulation of exopolysaccharides and pili by ExpR enables S. meliloti to achieve a coordinated expression of cellular processes during early stages of host interaction.
Collapse
|
46
|
Cho E, Kwon C, Lee S, Tahir MN, Park S, Jung S. Biotinylation of the rhizobial cyclic β-glucans and succinoglycans crucial for symbiosis with legumes. Carbohydr Res 2013; 389:141-6. [PMID: 24445053 DOI: 10.1016/j.carres.2013.12.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 12/11/2013] [Accepted: 12/18/2013] [Indexed: 10/25/2022]
Abstract
The cyclic β-glucans and succinoglycans produced by rhizobia are required for nodulation during symbiosis with legume hosts. However, only gene deletion analyses have been used to investigate their biological importance. For future studies on the physiological activity of those during symbiosis, biochemical methods need to be developed with separate carbohydrate compounds. Here, we isolated and purified rhizobial cellular carbohydrates using various chromatographic methods. Purified cyclic β-glucans, cyclosophoraoses, were monofunctionalized with biotin using the following three steps: tosylation, azidation, and amination. The mono-6-amino-cyclosophoraoses were linked with biotinamidohexanoic acid N-hydroxysuccinimide ester. Succinoglycans and monomers were tagged with biotinamidocaproyl hydrazide at the reducing sugar via reductive amination. The resulting biotinylated rhizobial carbohydrates were characterized by Fourier transform infrared and nuclear magnetic resonance spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy, and electrospray ionization mass spectrometry. The resulting neoglycoconjugates can be used as solid probes to study putative plant receptors and for non-invasive imaging for in vivo tracing.
Collapse
Affiliation(s)
- Eunae Cho
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center (BMIC) & Institute for Ubiquitous Information Technology and Applications (CBRU), Konkuk University, 1 Hwayang-dong Gwangjin-gu, Seoul 143-701, Republic of Korea
| | - Chanho Kwon
- NaraeBiotech, Incorporation R&D Center, 177, Dangha-ri, Bongdam-eup, Hwaseong-si, Gyeonggi-do 445-892, Republic of Korea
| | - Sanghoo Lee
- Department of Bioanalysis, Seoul Medical Science Institute, Seoul 140-809, Republic of Korea
| | - Muhammad Nazir Tahir
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center (BMIC) & Institute for Ubiquitous Information Technology and Applications (CBRU), Konkuk University, 1 Hwayang-dong Gwangjin-gu, Seoul 143-701, Republic of Korea
| | - Seyeon Park
- Department of Applied Chemistry, Dongduk Women's University, Seoul 136-714, Republic of Korea
| | - Seunho Jung
- Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center (BMIC) & Institute for Ubiquitous Information Technology and Applications (CBRU), Konkuk University, 1 Hwayang-dong Gwangjin-gu, Seoul 143-701, Republic of Korea.
| |
Collapse
|
47
|
Functional conservation of the capacity for ent-kaurene biosynthesis and an associated operon in certain rhizobia. J Bacteriol 2013; 196:100-6. [PMID: 24142247 DOI: 10.1128/jb.01031-13] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial interactions with plants are accompanied by complex signal exchange processes. Previously, the nitrogen-fixing symbiotic (rhizo)bacterium Bradyrhizobium japonicum was found to carry adjacent genes encoding two sequentially acting diterpene cyclases that together transform geranylgeranyl diphosphate to ent-kaurene, the olefin precursor to the gibberellin plant hormones. Species from the three other major genera of rhizobia were found to have homologous terpene synthase genes. Cloning and functional characterization of a representative set of these enzymes confirmed the capacity of each genus to produce ent-kaurene. Moreover, comparison of their genomic context revealed that these diterpene synthases are found in a conserved operon which includes an adjacent isoprenyl diphosphate synthase, shown here to produce the geranylgeranyl diphosphate precursor, providing a critical link to central metabolism. In addition, the rest of the operon consists of enzymatic genes that presumably lead to a more elaborated diterpenoid, although the production of gibberellins was not observed. Nevertheless, it has previously been shown that the operon is selectively expressed during nodulation, and the scattered distribution of the operon via independent horizontal gene transfer within the symbiotic plasmid or genomic island shown here suggests that such diterpenoid production may modulate the interaction of these particular symbionts with their host plants.
Collapse
|
48
|
Jones KM, Mendis HC, Queiroux C. Single-plant, sterile microcosms for nodulation and growth of the legume plant Medicago truncatula with the rhizobial symbiont Sinorhizobium meliloti. J Vis Exp 2013. [PMID: 24121837 DOI: 10.3791/50916] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Rhizobial bacteria form symbiotic, nitrogen-fixing nodules on the roots of compatible host legume plants. One of the most well-developed model systems for studying these interactions is the plant Medicago truncatula cv. Jemalong A17 and the rhizobial bacterium Sinorhizobium meliloti 1021. Repeated imaging of plant roots and scoring of symbiotic phenotypes requires methods that are non-destructive to either plants or bacteria. The symbiotic phenotypes of some plant and bacterial mutants become apparent after relatively short periods of growth, and do not require long-term observation of the host/symbiont interaction. However, subtle differences in symbiotic efficiency and nodule senescence phenotypes that are not apparent in the early stages of the nodulation process require relatively long growth periods before they can be scored. Several methods have been developed for long-term growth and observation of this host/symbiont pair. However, many of these methods require repeated watering, which increases the possibility of contamination by other microbes. Other methods require a relatively large space for growth of large numbers of plants. The method described here, symbiotic growth of M. truncatula/S. meliloti in sterile, single-plant microcosms, has several advantages. Plants in these microcosms have sufficient moisture and nutrients to ensure that watering is not required for up to 9 weeks, preventing cross-contamination during watering. This allows phenotypes to be quantified that might be missed in short-term growth systems, such as subtle delays in nodule development and early nodule senescence. Also, the roots and nodules in the microcosm are easily viewed through the plate lid, so up-rooting of the plants for observation is not required.
Collapse
|
49
|
Mendis HC, Queiroux C, Brewer TE, Davis OM, Washburn BK, Jones KM. The succinoglycan endoglycanase encoded by exoK is required for efficient symbiosis of Sinorhizobium meliloti 1021 with the host plants Medicago truncatula and Medicago sativa (Alfalfa). MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:1089-1105. [PMID: 23656330 DOI: 10.1094/mpmi-03-13-0087-r] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The acidic polysaccharide succinoglycan produced by the nitrogen-fixing rhizobial symbiont Sinorhizobium meliloti 1021 is required for this bacterium to invade the host plant Medicago truncatula and to efficiently invade the host plant M. sativa (alfalfa). The β-glucanase enzyme encoded by exoK has previously been demonstrated to cleave succinoglycan and participate in producing the low molecular weight form of this polysaccharide. Here, we show that exoK is required for efficient S. meliloti invasion of both M. truncatula and alfalfa. Deletion mutants of exoK have a substantial reduction in symbiotic productivity on both of these plant hosts. Insertion mutants of exoK have an even less productive symbiosis than the deletion mutants with the host M. truncatula that is caused by a secondary effect of the insertion itself, and may be due to a polar effect on the expression of the downstream exoLAMON genes.
Collapse
Affiliation(s)
- Hajeewaka C Mendis
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370, USA
| | | | | | | | | | | |
Collapse
|
50
|
Serrato RV, Meneses CHSG, Vidal MS, Santana-Filho AP, Iacomini M, Sassaki GL, Baldani JI. Structural studies of an exopolysaccharide produced by Gluconacetobacter diazotrophicus Pal5. Carbohydr Polym 2013; 98:1153-9. [PMID: 23987457 DOI: 10.1016/j.carbpol.2013.07.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 06/27/2013] [Accepted: 07/09/2013] [Indexed: 11/15/2022]
Abstract
Gluconacetobacter diazotrophicus is a nitrogen-fixing bacterium that has been found colonizing several plants. This acid-tolerant bacterium produces phytohormones that promote plant growth and is also able to grow in high-sugar concentrations. It has been demonstrated that exopolysaccharides (EPS), which are produced by strain Pal5 of G. diazotrophicus, play an important role in plant infection. We have investigated the structure of the EPS, which was produced by a strain of Pal5 grown in liquid medium containing mannitol as the sole carbon source. The results reveal an EPS with Glc, Gal, Man in a molar ratio of 6:3:1, respectively. NMR spectroscopy and chemical derivatization have revealed that the EPS structure has 4-O-substituted units of β-glucose, 3-O-substituted units of β-galactose and 2-O-substituted units of α-mannose. Glucose and galactose units linked at C6 were also found. The structure proposed herein is different from EPS produced by other species of Gluconacetobacter published to date.
Collapse
Affiliation(s)
- Rodrigo V Serrato
- Setor Litoral, Universidade Federal do Paraná - UFPR, Rua Jaguariaíva 512, 83260-000 Matinhos, PR, Brazil.
| | | | | | | | | | | | | |
Collapse
|