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Xu X, Du L, Wang M, Zhang R, Shan J, Qiao Y, Peng Q, Shi B. Antihyperglycemic, Antiaging, and L. brevis Growth-Promoting Activities of an Exopolysaccharide from Agrobacterium sp. FN01 (Galacan) Evaluated in a Zebrafish ( Danio rerio) Model. Foods 2024; 13:2729. [PMID: 39272494 PMCID: PMC11394834 DOI: 10.3390/foods13172729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2024] [Revised: 08/24/2024] [Accepted: 08/26/2024] [Indexed: 09/15/2024] Open
Abstract
Agrobacterium sp. are notable for their ability to produce substantial amounts of exopolysaccharides. Our study identified an exopolysaccharide (Galacan, 4982.327 kDa) from Agrobacterium sp. FN01. Galacan is a heteropolysaccharide primarily composed of glucose and galactose at a molar ratio of 25:1. The FT-IR results suggested that Galacan had typical absorption peaks of polysaccharide. The results of periodate oxidation, Smith degradation, and NMR confirmed the presence of structural units, such as β-D-Galp(→, →3)β-D-Galp(1→, →2,3)β-D-Glcp(1→, β-D-Glcp(1→, and →2)β-D-Glcp(1→. Galacan demonstrated significant biological activities. In experiments conducted with zebrafish, it facilitated the proliferation of Lactobacillus brevis in the intestinal tract, suggesting potential prebiotic properties. Moreover, in vivo studies revealed its antihyperglycemic effects, as evidenced by significant reductions in blood glucose levels and enhanced fluorescence intensity of pancreatic β cells in a streptozotocin (STZ)-induced hyperglycemic zebrafish model. Additionally, antiaging assays demonstrated Galacan's ability to inhibit β-galactosidase activity and enhance telomerase activity in a hydrogen peroxide (HP)-induced aging zebrafish model. These findings emphasized the potential of Galacan as a natural prebiotic with promising applications in diabetes prevention and antiaging interventions.
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Affiliation(s)
- Xiaoqing Xu
- Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Beijing 100081, China
| | - Lingling Du
- Chengdu Sydix Biotech Co., Ltd., Building 1A, Chengdu Hi-Tech Incubation Park, No. 1480 Tianfu Avenue North, Hi-Tech Zone, Chengdu 610095, China
| | - Meng Wang
- Chengdu Sydix Biotech Co., Ltd., Building 1A, Chengdu Hi-Tech Incubation Park, No. 1480 Tianfu Avenue North, Hi-Tech Zone, Chengdu 610095, China
| | - Ran Zhang
- Chengdu Sydix Biotech Co., Ltd., Building 1A, Chengdu Hi-Tech Incubation Park, No. 1480 Tianfu Avenue North, Hi-Tech Zone, Chengdu 610095, China
| | - Junjie Shan
- Academy of Military Medical Sciences Institute of Pharmacology and Toxicology, Beijing 100039, China
| | - Yu Qiao
- Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Beijing 100081, China
| | - Qing Peng
- Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Beijing 100081, China
| | - Bo Shi
- Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Beijing 100081, China
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Tributyltin in Wastewater: Influence on the Performance of Suspended Growth Biological Processes. WATER 2022. [DOI: 10.3390/w14091483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
The aim of this study was to evaluate the potential effect of tributyltin (TBT) on the performance of suspended-growth biological processes. The influence of TBT was evaluated for (i) the endogenous and exogenous respirations of heterotrophic micro-organisms in laboratory-scale batch reactors, taken from a municipal wastewater treatment plant and (ii) chemical oxygen demand (COD) removal, sludge production and oxygen consumption of a pilot-sale membrane bioreactor (MBR) system inoculated with heterotrophic micro-organisms taken from a MBR system. The batch experiments showed that the presence of TBT was likely to modify the activity of bacterial populations in endogenous conditions. The increase in endogenous oxygen needs suggested an increase in the maintenance requirements, essentially to manage the chemical stress induced by the presence of TBT. If the addition of TBT did not perturb COD removal in an MBR system, it limited sludge production and increased oxygen requirements; it is assumed that these modifications were linked with the necessity for the biomass to adapt in this stressful environment, as reflected by an increase in the maintenance requirements. These results emphasised that the respiratory activity of the bacterial cultures was modified by the presence of TBT, in the sense that an excess of oxygen was required to adapt to this chemical stress.
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Purification, characterization and functional properties of exopolysaccharide from a novel halophilic Natronotalea sambharensis sp. nov. Int J Biol Macromol 2019; 136:547-558. [DOI: 10.1016/j.ijbiomac.2019.06.080] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 05/30/2019] [Accepted: 06/11/2019] [Indexed: 12/13/2022]
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Chikkanna A, Ghosh D, Kishore A. Expression and characterization of a potential exopolysaccharide from a newly isolated halophilic thermotolerant bacteria Halomonas nitroreducens strain WB1. PeerJ 2018; 6:e4684. [PMID: 29707437 PMCID: PMC5922230 DOI: 10.7717/peerj.4684] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 04/09/2018] [Indexed: 11/20/2022] Open
Abstract
The halophilic bacterial strain WB1 isolated from a hydrothermal vent was taxonomically characterized using multiple proxies, as Halomonas nitroreducens strain WB1. When grown on malt extract/yeast extract (MY) medium, it produced large quantities of exopolysaccharide (EPS). The polymer was synthesized at a higher rate during the log and early stationary phases. The anionic polysaccharide is primarily composed of glucose, mannose, and galactose. The studied EPS was highly viscous and had pseudoplastic nature. The EPS was found to be a mixture of three polysaccharides under FT-IR, which makes it less labile to environmental diagenesis. It also has emulsifying and antioxidant activity along with the binding capacity to heavy metals. The EPS has unique and interesting physical and chemical properties, which are different from earlier reported exo-polysaccharides produced by different bacterial genus. This suggests that the extreme geological niches like hypersaline, hyperthermal, hypothermal, and oligophilic environments, which are not well studied so far, can offer extensive and potential resources for medical, biotechnological and industrial applications. The study clearly showed that the thermal springs from the temperate region can be a potent source of many such industrially important microbial genera and need further detailed studies to be carried out.
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Affiliation(s)
- Arpitha Chikkanna
- Laboratory of Biogeochem-mystery, Centre for Earth Sciences, Indian Institute of Science, Bangalore, Karnataka, India
| | - Devanita Ghosh
- Laboratory of Biogeochem-mystery, Centre for Earth Sciences, Indian Institute of Science, Bangalore, Karnataka, India
| | - Abhinoy Kishore
- Center for Nanoscience and Engineering, Indian Institute of Science, Bangalore, Karnataka, India
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Hussain A, Zia KM, Tabasum S, Noreen A, Ali M, Iqbal R, Zuber M. Blends and composites of exopolysaccharides; properties and applications: A review. Int J Biol Macromol 2017; 94:10-27. [DOI: 10.1016/j.ijbiomac.2016.09.104] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2016] [Revised: 09/23/2016] [Accepted: 09/29/2016] [Indexed: 01/21/2023]
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Schäffer C, Messner P. Emerging facets of prokaryotic glycosylation. FEMS Microbiol Rev 2016; 41:49-91. [PMID: 27566466 DOI: 10.1093/femsre/fuw036] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 02/17/2016] [Accepted: 08/01/2016] [Indexed: 12/16/2022] Open
Abstract
Glycosylation of proteins is one of the most prevalent post-translational modifications occurring in nature, with a wide repertoire of biological implications. Pathways for the main types of this modification, the N- and O-glycosylation, can be found in all three domains of life-the Eukarya, Bacteria and Archaea-thereby following common principles, which are valid also for lipopolysaccharides, lipooligosaccharides and glycopolymers. Thus, studies on any glycoconjugate can unravel novel facets of the still incompletely understood fundamentals of protein N- and O-glycosylation. While it is estimated that more than two-thirds of all eukaryotic proteins would be glycosylated, no such estimate is available for prokaryotic glycoproteins, whose understanding is lagging behind, mainly due to the enormous variability of their glycan structures and variations in the underlying glycosylation processes. Combining glycan structural information with bioinformatic, genetic, biochemical and enzymatic data has opened up an avenue for in-depth analyses of glycosylation processes as a basis for glycoengineering endeavours. Here, the common themes of glycosylation are conceptualised for the major classes of prokaryotic (i.e. bacterial and archaeal) glycoconjugates, with a special focus on glycosylated cell-surface proteins. We describe the current knowledge of biosynthesis and importance of these glycoconjugates in selected pathogenic and beneficial microbes.
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Affiliation(s)
- Christina Schäffer
- Department of NanoBiotechnology, Institute of Biologically Inspired Materials, NanoGlycobiology unit, Universität für Bodenkultur Wien, A-1180 Vienna, Austria
| | - Paul Messner
- Department of NanoBiotechnology, Institute of Biologically Inspired Materials, NanoGlycobiology unit, Universität für Bodenkultur Wien, A-1180 Vienna, Austria
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Exopolysaccharides of Halophilic Microorganisms: An Overview. Ind Biotechnol (New Rochelle N Y) 2016. [DOI: 10.1201/b19347-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Abstract
Prokaryotic glycosylation fulfills an important role in maintaining and protecting the structural integrity and function of the bacterial cell wall, as well as serving as a flexible adaption mechanism to evade environmental and host-induced pressure. The scope of bacterial and archaeal protein glycosylation has considerably expanded over the past decade(s), with numerous examples covering the glycosylation of flagella, pili, glycosylated enzymes, as well as surface-layer proteins. This article addresses structure, analysis, function, genetic basis, biosynthesis, and biomedical and biotechnological applications of cell-envelope glycoconjugates, S-layer glycoprotein glycans, and "nonclassical" secondary-cell wall polysaccharides. The latter group of polymers mediates the important attachment and regular orientation of the S-layer to the cell wall. The structures of these glycopolymers reveal an enormous diversity, resembling the structural variability of bacterial lipopolysaccharides and capsular polysaccharides. While most examples are presented for Gram-positive bacteria, the S-layer glycan of the Gram-negative pathogen Tannerella forsythia is also discussed. In addition, archaeal S-layer glycoproteins are briefly summarized.
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Affiliation(s)
- Paul Messner
- Department of NanoBiotechnology, NanoGlycobiology Unit, University of Natural Resources and Life Sciences, Vienna, Austria
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O-Acetyl location on Cepacian, the principal exopolysaccharide of Burkholderia cepacia complex bacteria. Carbohydr Res 2011; 346:2905-12. [DOI: 10.1016/j.carres.2011.10.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Revised: 10/04/2011] [Accepted: 10/07/2011] [Indexed: 11/21/2022]
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Elboutachfaiti R, Delattre C, Petit E, Michaud P. Polyglucuronic acids: Structures, functions and degrading enzymes. Carbohydr Polym 2011. [DOI: 10.1016/j.carbpol.2010.10.063] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Jiang J, Zhang R, Cui Z, He J, Gu L, Li S. Parameters controlling the gene-targeting frequency at the Sphingomonas species rrn site and expression of the methyl parathion hydrolase gene. J Appl Microbiol 2007; 102:1578-85. [PMID: 17578423 DOI: 10.1111/j.1365-2672.2006.03184.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
AIMS To investigate the key parameters controlling the exogenous methyl parathion hydrolase (MPH) gene mpd-targeting frequency at the ribosomal RNA operon (rrn) site of Sphingomonas species which has a wide range of biotechnological applications. METHODS AND RESULTS Targeting vectors with different homology lengths and recipient target DNA with different homology identities were used to investigate the parameters controlling the targeting frequency at the Sphingomonas species rrn site. Targeting frequency decreased with the reduction of homology length, and the minimal size for normal homologous recombination was >100 bp. Homologous recombination could succeed even if there were 3-4% mismatches; however, targeting frequency decreased with increasing sequence divergence. The Red recombination system could increase the targeting frequency to some extent. Targeting of the mpd gene to the rrn site did not affect cell viability and resulted in an increase of MPH-specific activity in recombinants. CONCLUSIONS Targeting frequency was affected by homology length, identity and the Red recombination system. The rrn site is a good target site for the expression of exogenous genes. SIGNIFICANCE AND IMPACT OF THE STUDY This work is useful as a foundation for a better understanding of recombination events involving homologous sequences and for the improved manipulation of Sphingomonas genes in biotechnological applications.
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Affiliation(s)
- J Jiang
- Department of Microbiology, Key Laboratory for Microbiological Engineering of Agricultural Environment of Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China
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Functional biopolymers produced by biochemical technology considering applications in food engineering. KOREAN J CHEM ENG 2007. [DOI: 10.1007/s11814-007-0047-1] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
Microbial polysaccharides are multifunctional and can be divided into intracellular polysaccharides, structural polysaccharides and extracellular polysaccharides or exopolysaccharides (EPS). Extracellular polymeric substances (EPS), produced by both prokaryotes (eubacteria and archaebacteria) and eukaryotes (phytoplankton, fungi, and algae), have been of topical research interest. Newer approaches are carried out today to replace the traditionally used plant gums by their bacterial counterparts. The bacterial exopolysaccharides represent a wide range of chemical structures, but have not yet acquired appreciable significance. Chemically, EPS are rich in high molecular weight polysaccharides (10 to 30 kDa) and have heteropolymeric composition. They have new-fangled applications due to the unique properties they possess. Owing to this, exopolysaccharides have found multifarious applications in the food, pharmaceutical and other industries. Hence, the present article converges on bacterial exopolysaccharides.
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Affiliation(s)
- Anita Suresh Kumar
- Central Salt and Marine Chemicals Research Institute, Bhavnagar, Gujarat, India
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Khan T, Khan H, Park JK. Physical properties of a single sugar α-linked glucuronic acid-based oligosaccharide produced by a Gluconacetobacter hansenii strain. Process Biochem 2007. [DOI: 10.1016/j.procbio.2006.08.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Aslim B, Beyatli Y, Yuksekdag ZN. Productions and monomer compositions of exopolysaccharides by Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus strains isolated from traditional home-made yoghurts and raw milk. Int J Food Sci Technol 2006. [DOI: 10.1111/j.1365-2621.2005.01155.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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17
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Pal R, Bhasin VK, Lal R. Proposal to reclassify [Sphingomonas] xenophaga Stolz et al. 2000 and [Sphingomonas] taejonensis Lee et al. 2001 as Sphingobium xenophagum comb. nov. and Sphingopyxis taejonensis comb. nov., respectively. Int J Syst Evol Microbiol 2006; 56:667-670. [PMID: 16514047 DOI: 10.1099/ijs.0.64161-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The sphingomonad group contains bacterial isolates that are quite diverse in terms of their phylogenetic, ecological and physiological properties. Thus, the genus Sphingomonas was divided into four distinct genera, Sphingomonas sensu stricto, Sphingobium, Novosphingobium and Sphingopyxis on the basis of 16S rRNA gene sequence phylogenetic analysis, signature nucleotides, fatty acid profiles and polyamine patterns and this classification is currently widely accepted. In this study, a complete analysis of the 16S rRNA gene sequences of all the members of the group of sphingomonads encompassed in the genera Sphingomonas sensu stricto, Sphingobium, Novosphingobium and Sphingopyxis was inferred by using tree-making algorithms. [Sphingomonas] xenophaga DSM 6383T was found to form a distinct clade with the members of the genus Sphingobium, whereas [Sphingomonas] taejonensis DSM 15583T forms a clade with the members of the genus Sphingopyxis. The respective positions of these strains were also supported by the data for signature nucleotides, 2-hydroxy fatty acid profiles, polyamine patterns and the nitrate reduction properties of the strains. We therefore propose the reclassification of [Sphingomonas] xenophaga and [Sphingomonas] taejonensis as Sphingobium xenophagum comb. nov. (type strain DSM 6383T = CIP 107206T) and Sphingopyxis taejonensis comb. nov. (type strain DSM 15583T = KCTC 2884T = KCCM 41068T), respectively.
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Affiliation(s)
- Rinku Pal
- Molecular Biology Laboratory, Department of Zoology, University of Delhi, Delhi - 110007, India
| | - V K Bhasin
- Molecular Biology Laboratory, Department of Zoology, University of Delhi, Delhi - 110007, India
| | - Rup Lal
- Molecular Biology Laboratory, Department of Zoology, University of Delhi, Delhi - 110007, India
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Arco Y, Llamas I, Martínez-Checa F, Argandoña M, Quesada E, Moral AD. epsABCJ genes are involved in the biosynthesis of the exopolysaccharide mauran produced by Halomonas maura. Microbiology (Reading) 2005; 151:2841-2851. [PMID: 16151197 DOI: 10.1099/mic.0.27981-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The moderately halophilic strainHalomonas mauraS-30 produces a high-molecular-mass acidic polymer (4·7×106 Da) composed of repeating units of mannose, galactose, glucose and glucuronic acid. This exopolysaccharide (EPS), known as mauran, has interesting functional properties that make it suitable for use in many industrial fields. Analysis of the flanking regions of a mini-Tn5insertion site in an EPS-deficient mutant ofH. maura, strain TK71, led to the identification of five ORFs (epsABCDJ), which form part of a gene cluster (eps) with the same structural organization as others involved in the biosynthesis of group 1 capsules and some EPSs. Conserved genetic features were found such as JUMPstart andopselements, which are characteristically located preceding the gene clusters for bacterial polysaccharides. On the basis of their amino-acid-sequence homologies, their putative hydropathy profiles and the effect of their mutations, it is predicted that EpsA (an exporter-protein homologue belonging to the OMA family) and EpsC (a chain-length-regulator homologue belonging to the PCP family) play a role in the assembly, polymerization and translocation of mauran. The possibility that mauran might be synthesized via a Wzy-like biosynthesis system, just as it is for many other polysaccharides, is also discussed. This hypothesis is supported by the fact that EpsJ is homologous with some members of the PST-exporter-protein family, which seems to function together with each OMA–PCP pair in polysaccharide transport in Gram-negative bacteria, transferring the assembled lipid-linked repeating units from the cytoplasmic membrane to the periplasmic space. Maximum induction of theepsgenes is reached during stationary phase in the presence of 5 % (w/v) marine salts.
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Affiliation(s)
- Yolanda Arco
- Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071, Granada, Spain
| | - Inmaculada Llamas
- Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071, Granada, Spain
| | - Fernando Martínez-Checa
- Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071, Granada, Spain
| | - Montserrat Argandoña
- Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071, Granada, Spain
| | - Emilia Quesada
- Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071, Granada, Spain
| | - Ana Del Moral
- Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071, Granada, Spain
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Schäffer C, Messner P. The structure of secondary cell wall polymers: how Gram-positive bacteria stick their cell walls together. MICROBIOLOGY-SGM 2005; 151:643-651. [PMID: 15758211 DOI: 10.1099/mic.0.27749-0] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The cell wall of Gram-positive bacteria has been a subject of detailed chemical study over the past five decades. Outside the cytoplasmic membrane of these organisms the fundamental polymer is peptidoglycan (PG), which is responsible for the maintenance of cell shape and osmotic stability. In addition, typical essential cell wall polymers such as teichoic or teichuronic acids are linked to some of the peptidoglycan chains. In this review these compounds are considered as 'classical' cell wall polymers. In the course of recent investigations of bacterial cell surface layers (S-layers) a different class of 'non-classical' secondary cell wall polymers (SCWPs) has been identified, which is involved in anchoring of S-layers to the bacterial cell surface. Comparative analyses have shown considerable differences in chemical composition, overall structure and charge behaviour of these SCWPs. This review discusses the progress that has been made in understanding the structural principles of SCWPs, which may have useful applications in S-layer-based 'supramolecular construction kits' in nanobiotechnology.
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Affiliation(s)
- Christina Schäffer
- Zentrum für NanoBiotechnologie, Universität für Bodenkultur Wien, A-1180 Wien, Austria
| | - Paul Messner
- Zentrum für NanoBiotechnologie, Universität für Bodenkultur Wien, A-1180 Wien, Austria
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Llamas I, Suárez A, Quesada E, Béjar V, del Moral A. Identification and characterization of the carAB genes responsible for encoding carbamoylphosphate synthetase in Halomonas eurihalina. Extremophiles 2003; 7:205-11. [PMID: 12768451 DOI: 10.1007/s00792-002-0311-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2002] [Accepted: 12/02/2002] [Indexed: 10/28/2022]
Abstract
Halomonas eurihalina is a moderately halophilic bacterium which produces exopolysaccharides potentially of great use in many fields of industry and ecology. Strain F2-7 of H. eurihalina synthesizes an anionic exopolysaccharide known as polymer V2-7, which not only has emulsifying activity but also becomes viscous under acidic conditions, and therefore we consider it worthwhile making a detailed study of the genetics of this strain. By insertional mutagenesis using the mini-Tn 5 Km2 transposon we isolated and characterized a mutant strain, S36 K, which requires both arginine and uracil for growth and does not excrete EPS. S36 K carries a mutation within the carB gene that encodes the synthesis of the large subunit of the carbamoylphosphate synthetase enzyme, which in turn catalyzes the synthesis of carbamoylphosphate, an important precursor of arginine and pyrimidines. We describe here the cloning and characterization of the carAB genes, which encode carbamoylphosphate synthetase in Halomonas eurihalina, and discuss this enzyme's possible role in the pathways for the synthesis of exopolysaccharides in strain F2-7.
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Affiliation(s)
- Inmaculada Llamas
- Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071 Granada, Spain
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Laws A, Gu Y, Marshall V. Biosynthesis, characterisation, and design of bacterial exopolysaccharides from lactic acid bacteria. Biotechnol Adv 2001; 19:597-625. [PMID: 14550013 DOI: 10.1016/s0734-9750(01)00084-2] [Citation(s) in RCA: 176] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lactic acid bacteria (LAB) are characterised by their conversion of a large proportion of their carbon feed, fermentable sugars, to lactic acid. However, in addition to lactic acid production, the LAB are able to divert a small proportion of fermentable sugars towards the biosynthesis of exopolysaccharides (EPSs) that are independent of the cell surface and cell wall material. These microbial EPSs when suspended or dissolved in aqueous solution provide thickening and gelling properties, and, as such, there is great interest in using EPSs from food grade microorganisms (such as the LAB that are traditionally used for food fermentations) for use as thickening agents. The current review includes a brief summary of the recent literature describing features of the biosynthetic pathways leading to EPS production. Many aspects of EPS biosynthesis in LAB are still not fully understood and a number of inferences are made regarding the similarity of the pathway to those involved in the synthesis of other cell polysaccharides, e.g., cell wall components. The main body of the review will cover practical aspects concerned with the isolation and characterisation of EPS structures. In the last couple of years, a substantial number of structures have been published and a summary of the common elements of these structures is included as is a suggestion for a system for representing structures. A brief highlight of the attempts that are being made to design 'tailor'-made polysaccharides using genetic modification and control of metabolic flux is presented.
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Affiliation(s)
- A Laws
- School of Applied Sciences, University of Huddersfield, Queensgate, UK.
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