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Systematic optimization of exopolysaccharide production by Gluconacetobacter sp. and use of (crude) glycerol as carbon source. Carbohydr Polym 2022; 276:118769. [PMID: 34823788 DOI: 10.1016/j.carbpol.2021.118769] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 10/12/2021] [Accepted: 10/12/2021] [Indexed: 11/23/2022]
Abstract
The usage of polysaccharides as biodegradable polymers is of growing interest in the context of a sustainable and ecofriendly economy. For this, the production of exopolysaccharides (EPS) by Gluconacetobacter sp. was investigated. Glycerol as carbon source revealed to be beneficial compared to glucose. In addition, pure glycerol could be substituted by a crude glycerol waste stream from biodiesel production. Systematic analysis of the peptone and phosphate concentrations in glycerol-based media indicated a strong effect of peptone. Optimized parameters resulted in a titer of 25.4 ± 2.4 g/L EPS with a productivity of 0.46 ± 0.04 g*(L*h)-1. With decreasing peptone, a variation in the monomer ratios was observed. An accompanying change in molecular size distribution indicated the production of two different polysaccharides. Intensified analysis revealed the main polysaccharide to be composed of glucose (Glc), galactose (Gal), mannose (Man) and glucuronic acid (GlcA), and the minor polysaccharide of Gal, Man, ribose (Rib).
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Ryngajłło M, Kubiak K, Jędrzejczak-Krzepkowska M, Jacek P, Bielecki S. Comparative genomics of the Komagataeibacter strains-Efficient bionanocellulose producers. Microbiologyopen 2018; 8:e00731. [PMID: 30365246 PMCID: PMC6528568 DOI: 10.1002/mbo3.731] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 08/13/2018] [Accepted: 08/21/2018] [Indexed: 12/21/2022] Open
Abstract
Komagataeibacter species are well-recognized bionanocellulose (BNC) producers. This bacterial genus, formerly assigned to Gluconacetobacter, is known for its phenotypic diversity manifested by strain-dependent carbon source preference, BNC production rate, pellicle structure, and strain stability. Here, we performed a comparative study of nineteen Komagataeibacter genomes, three of which were newly contributed in this work. We defined the core genome of the genus, clarified phylogenetic relationships among strains, and provided genetic evidence for the distinction between the two major clades, the K. xylinus and the K. hansenii. We found genomic traits, which likely contribute to the phenotypic diversity between the Komagataeibacter strains. These features include genome flexibility, carbohydrate uptake and regulation of its metabolism, exopolysaccharides synthesis, and the c-di-GMP signaling network. In addition, this work provides a comprehensive functional annotation of carbohydrate metabolism pathways, such as those related to glucose, glycerol, acetan, levan, and cellulose. Findings of this multi-genomic study expand understanding of the genetic variation within the Komagataeibacter genus and facilitate exploiting of its full potential for bionanocellulose production at the industrial scale.
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Affiliation(s)
- Małgorzata Ryngajłło
- Institute of Technical Biochemistry, Lodz University of Technology, Lodz, Poland
| | - Katarzyna Kubiak
- Institute of Technical Biochemistry, Lodz University of Technology, Lodz, Poland
| | | | - Paulina Jacek
- Institute of Technical Biochemistry, Lodz University of Technology, Lodz, Poland
| | - Stanisław Bielecki
- Institute of Technical Biochemistry, Lodz University of Technology, Lodz, Poland
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Škraban J, Cleenwerck I, Vandamme P, Fanedl L, Trček J. Genome sequences and description of novel exopolysaccharides producing species Komagataeibacter pomaceti sp. nov. and reclassification of Komagataeibacter kombuchae (Dutta and Gachhui 2007) Yamada et al., 2013 as a later heterotypic synonym of Komagataeibacter hansenii (Gosselé et al. 1983) Yamada et al., 2013. Syst Appl Microbiol 2018; 41:581-592. [PMID: 30177404 DOI: 10.1016/j.syapm.2018.08.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 08/07/2018] [Accepted: 08/10/2018] [Indexed: 11/30/2022]
Abstract
Strains T5K1 and AV446 isolated from apple cider vinegars during a submerged vinegar production in two separate vinegar facilities showed 94% 16S rRNA gene similarity to its closest neighbors Komagataeibacter maltaceti LMG 1529T and Gluconacetobacter entanii LTH 4560T. Further phylogenetic and phenotypic characterizations indicated that the isolates belonged to a novel species of the Komagataeibacter genus. Comparison based on 16S-23S rRNA gene ITS sequences and concatenated partial sequences of the housekeeping genes dnaK, groEL and rpoB, grouped both strains to a single phylogenetic cluster well separated from the other species of the Komagataeibacter genus. Average nucleotide identity of T5K1 and AV446 draft genome sequences compared to other Komagataeibacter type strains was below 94% and at the same time, in-silico DNA-DNA hybridization was below 70%. Both strains on the other hand showed approximately 98% (average nucleotide identity) and 87% (in silico DNA-DNA hybridization) similarity to each other. Strains T5K1 and AV446 can be differentiated from other Komagataeibacter type strains based on their ability to produce 2-keto-d-gluconic acid and at the same time inability to produce 5-keto-d-gluconic acid. Furthermore, strains of the new species do not grow on Asai medium supplemented with d-glucose or d-mannitol. The growth is also absent (T5K1) or weak (AV446) on Hoyer-Frateur medium supplemented with afore mentioned sugars. Both strains produce cellulose. In addition, draft genome analysis revealed that strains T5K1 and AV446 possess genes involved in the synthesis of acetan-like extracellular heteropolysaccharide. We propose the name Komagataeibacter pomaceti sp. nov. for the new species with LMG 30150T [=CCM 8723T=ZIM B1029T] as the type strain. Data collected in this study and in a previous study also revealed that Komagataeibacter kombuchae is a later heterotypic synonym of Komagataeibacter hansenii.
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Affiliation(s)
- Jure Škraban
- University of Maribor, Faculty of Natural Sciences and Mathematics, Department of Biology, Maribor, Slovenia
| | - Ilse Cleenwerck
- BCCM/LMG Bacteria Collection, Laboratory of Microbiology, Ghent University, Faculty of Sciences, Ghent, Belgium
| | - Peter Vandamme
- BCCM/LMG Bacteria Collection, Laboratory of Microbiology, Ghent University, Faculty of Sciences, Ghent, Belgium
| | - Lijana Fanedl
- University of Ljubljana, Biotechnical Faculty, Ljubljana, Slovenia
| | - Janja Trček
- University of Maribor, Faculty of Natural Sciences and Mathematics, Department of Biology, Maribor, Slovenia; University of Maribor, Faculty of Chemistry and Chemical Engineering, Maribor, Slovenia.
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Basu S, Omadjela O, Zimmer J, Catchmark JM. Impact of plant matrix polysaccharides on cellulose produced by surface-tethered cellulose synthases. Carbohydr Polym 2017; 162:93-99. [DOI: 10.1016/j.carbpol.2017.01.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 12/27/2016] [Accepted: 01/03/2017] [Indexed: 10/20/2022]
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Fang L, Catchmark JM. Characterization of cellulose and other exopolysaccharides produced from Gluconacetobacter strains. Carbohydr Polym 2015; 115:663-9. [DOI: 10.1016/j.carbpol.2014.09.028] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 09/03/2014] [Accepted: 09/11/2014] [Indexed: 10/24/2022]
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MacCormick C, Harris J, Jay A, Ridout M, Colquhoun I, Morris V. Isolation and characterization of a new extracellular polysaccharide from an Acetobacter species. ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1365-2672.1996.tb03528.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Ridout M, Cairns P, Brownsey G, Morris V. Synergistic interactions between the genetically modified bacterial polysaccharide P2 and carob or konjac mannan. Carbohydr Res 2004; 339:2233-9. [PMID: 15337451 DOI: 10.1016/j.carres.2004.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2004] [Revised: 06/15/2004] [Accepted: 07/10/2004] [Indexed: 10/26/2022]
Abstract
Rheological studies have confirmed that the bacterial polysaccharide P2, a genetically modified variant of the Acetobacter xylinum polysaccharide acetan, undergoes synergistic gelation with either of the plant polysaccharides carob or konjac mannan. X-ray fibre diffraction data shows that P2 can form a 5-fold helical structure of pitch 4.7nm and an axial rise per disaccharide repeat of 0.92nm. Optical rotation data demonstrate that P2 undergoes a coil-helix transition in solution and that deacylation enhances the stability of the helical structure in solution. Studies made on mixtures prepared at different temperatures and ionic strengths suggest that denaturation of the P2 helix favours interaction and gelation. Deacetylation of P2 enhances gelation. X-ray diffraction data for oriented fibres prepared from deacetylated P2-konjac mannan mixed films reveal a 6-fold helical structure of pitch 5.54nm with an axial rise per disaccharide repeat also of 0.92nm. This mixed helix provides direct evidence for binding between the two polysaccharides. P2 contains two sites of acetylation: one on the backbone and one on the sidechain. The former site of acetylation inhibits helix formation for P2. It is suggested that this site of acetylation also inhibits formation of the mixed helix, explaining the enhanced gelation of mixtures on deacetylation.
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Affiliation(s)
- Michael Ridout
- Institute of Food Research, Food Material Science, Norwich Research Park, Colney, Norwich NR4 7UA, UK
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Kornmann H, Valentinotti S, Duboc P, Marison I, von Stockar U. Monitoring and control of Gluconacetobacter xylinus fed-batch cultures using in situ mid-IR spectroscopy. J Biotechnol 2004; 113:231-45. [PMID: 15380658 DOI: 10.1016/j.jbiotec.2004.03.029] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2003] [Revised: 03/05/2004] [Accepted: 03/19/2004] [Indexed: 11/23/2022]
Abstract
A partial least-squares calibration model, relating mid-infrared spectral features with fructose, ethanol, acetate, gluconacetan, phosphate and ammonium concentrations has been designed to monitor and control cultivations of Gluconacetobacter xylinus and production of gluconacetan, a food grade exopolysaccharide (EPS). Only synthetic solutions containing a mixture of the major components of culture media have been used to calibrate the spectrometer. A factorial design has been applied to determine the composition and concentration in the calibration matrix. This approach guarantees a complete and intelligent scan of the calibration space using only 55 standards. This calibration model allowed standard errors of validation (SEV) for fructose, ethanol, acetate, gluconacetan, ammonium and phosphate concentrations of 1.16 g/l, 0.36 g/l, 0.22 g/l, 1.54 g/l, 0.24 g/l and 0.18 g/l, respectively. With G. xylinus, ethanol is directly oxidized to acetate, which is subsequently metabolized to form biomass. However, residual ethanol in the culture medium prevents bacterial growth. On-line spectroscopic data were implemented in a closed-loop control strategy for fed-batch fermentation. Acetate concentration was controlled at a constant value by feeding ethanol into the bioreactor. The designed fed-batch process allowed biomass production on ethanol. This was not possible in a batch process due to ethanol inhibition of bacterial growth. In this way, the productivity of gluconacetan was increased from 1.8 x 10(-3) [C-mol/C-mol substrate/h] in the batch process to 2.9 x 10(-3) [C-mol/C-mol substrate/h] in the fed-batch process described in this study.
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Affiliation(s)
- Henri Kornmann
- Serono Biotech Center, route de Fenil, ZI B, CH-1809 Fenil-sur-Corsier, Switzerland
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Kornmann H, Duboc P, Marison I, von Stockar U. Influence of nutritional factors on the nature, yield, and composition of exopolysaccharides produced by Gluconacetobacter xylinus I-2281. Appl Environ Microbiol 2004; 69:6091-8. [PMID: 14532066 PMCID: PMC201184 DOI: 10.1128/aem.69.10.6091-6098.2003] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The influence of substrate composition on the yield, nature, and composition of exopolysaccharides (EPS) produced by the food-grade strain Gluconacetobacter xylinus I-2281 was investigated during controlled cultivations on mixed substrates containing acetate and either glucose, sucrose, or fructose. Enzymatic activity analysis and acid hydrolysis revealed that two EPS, gluconacetan and levan, were produced by G. xylinus. In contrast to other acetic acid strains, no exocellulose formation has been measured. Considerable differences in metabolite yields have been observed with regard to the carbohydrate source. It was shown that glucose was inadequate for EPS production since most of this substrate (0.84 C-mol/C-mol) was oxidized into gluconic acid, 2-ketogluconic acid, and 5-ketogluconic acid. In contrast, sucrose and fructose supported a 0.35 C-mol/C-mol gluconacetan yield. In addition, growing G. xylinus on sucrose produced a 0.07 C-mol/C-mol levan yield. The composition of EPS remained unchanged during the course of the fermentations. Levan sucrase activity was found to be mainly membrane associated. In addition to levan production, an analysis of levan sucrase's activity also explained the formation of glucose oxides during fermentation on sucrose through the release of glucose. The biosynthetic pathway of gluconacetan synthesis has also been explored. Although the activity of key enzymes showed large differences to be a function of the carbon source, the ratio of their activities remained similar from one carbon source to another and corresponded to the ratio of precursor needs as deduced from the gluconacetan composition.
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Affiliation(s)
- Henri Kornmann
- Laboratory of Chemical and Biological Engineering, Institute of Chemical Engineering, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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Kornmann H, Valentinotti S, Marison I, von Stockar U. Real-time update of calibration model for better monitoring of batch processes using spectroscopy. Biotechnol Bioeng 2004; 87:593-601. [PMID: 15352057 DOI: 10.1002/bit.20153] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In order to reduce the large calibration matrix usually required for calibrating multiwavelength optical sensors, a simple algorithm based on the addition in process of new standards is proposed. A small calibration model, based on 14 standards, is periodically updated by spectra collected on-line during fermentation operation. Concentrations related to these spectra are reconciled into best-estimated values, by considering carbon and oxygen balances. Using this method, fructose, acetate, and gluconacetan were monitored during batch fermentations of Gluconacetobacter xylinus 12281 using mid-infrared spectroscopy. It is shown that this algorithm compensates for noncalibrated events such as production or consumption of by-products. The standard error of prediction (SEP) values were 0.99, 0.10, and 0.90 g/L for fructose, acetate, and gluconacetan, respectively. By contrast, without an updating of the calibration model, the SEP values were 2.46, 0.92, and 1.04 g/L for fructose, acetate, and gluconacetan, respectively. Using only 14 standards, it was therefore possible to approach the performance of an 88-standard-based calibration model having SEP values of 1.11, 0.37, and 0.79 g/L for fructose, acetate, and gluconacetan, respectively. Therefore, the proposed algorithm is a valuable approach to reduce the calibration time of multiwavelength optical sensors.
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Affiliation(s)
- Henri Kornmann
- Laboratory of Chemical and Biochemical Engineering, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland
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Chandrasekaran R, Janaswamy S, Morris VJ. Acetan:glucomannan interactions—a molecular modeling study. Carbohydr Res 2003; 338:2889-98. [PMID: 14667710 DOI: 10.1016/j.carres.2003.08.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
X-ray fiber diffraction patterns from deacylated acetan and glucomannan (konjac mannan) blends are diagnostic of good orientation and modest polycrystallinity. The meridional reflection on the sixth layer line suggests that the binary complex is a 6-fold helix of pitch 55.4 A. A molecular modeling study incorporating this information reveals that a double helix in which one strand is acetan and the other glucomannan is stereochemically feasible. While the backbone and side groups are sufficiently flexible to allow the chains to associate with the same or opposite polarity, the parallel model is superior in terms of unit cell packing. The results are compatible with the observed synergy; namely the weak gelation behavior of the complex. The molecular model can be generalized for the binary system when acetan is replaced by xanthan or glucomannan by galactomannan.
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Affiliation(s)
- Rengaswami Chandrasekaran
- Whistler Center for Carbohydrate Research, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907-2009, USA.
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Rabiu BA, Jay AJ, Gibson GR, Rastall RA. Synthesis and fermentation properties of novel galacto-oligosaccharides by beta-galactosidases from Bifidobacterium species. Appl Environ Microbiol 2001; 67:2526-30. [PMID: 11375159 PMCID: PMC92903 DOI: 10.1128/aem.67.6.2526-2530.2001] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
beta-Galactosidase enzymes were extracted from pure cultures of Bifidobacterium angulatum, B. bifidum BB-12, B. adolescentis ANB-7, B. infantis DSM-20088, and B. pseudolongum DSM-20099 and used in glycosyl transfer reactions to synthesize oligosaccharides from lactose. At a lactose concentration of 30% (wt/wt) oligosaccharide yields of 24.7 to 47.6% occurred within 7 h. Examination of the products by thin-layer chromatography and methylation analysis revealed distinct product derived spectra from each enzyme. These were found to be different to that of Oligomate 55, a commercial prebiotic galacto-oligosaccharide. Fermentation testing of the oligosaccharides showed an increase in growth rate, compared to Oligomate 55, with products derived from B. angulatum, B. bifidum, B. infantis, and B. pseudolongum. However B. adolescentis had a lower growth rates on its oligosaccharide compared with Oligomate 55. Mixed culture testing of the B. bifidum BS-4 oligosaccharide showed that the overall prebiotic effect was equivalent to that of Oligomate 55.
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Affiliation(s)
- B A Rabiu
- Division of Food Microbial Sciences, School of Food Biosciences, The University of Reading, Whiteknights, Reading RG6 6AP, United Kingdom
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Colquhoun IJ, Jay AJ, Eagles J, Morris VJ, Edwards KJ, Griffin AM, Gasson MJ. Structure and conformation of a novel genetically engineered polysaccharide P2. Carbohydr Res 2001; 330:325-33. [PMID: 11270811 DOI: 10.1016/s0008-6215(00)00293-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A new exocellular polysaccharide (P2) has been produced by the manipulation of a glycosyl transferase gene (aceP) involved in the biosynthesis of the polysaccharide acetan by the bacterium Acetobacter xylinum strain CKE5. The P2 polysaccharide has been studied by methylation analysis, reductive cleavage, and 1H and 13C NMR spectroscopy. The data are consistent with the structure predicted when the aceP gene is deactivated: [Molecular structure: see text]. The effect of cooling on proton NMR line width indicates a coil-helix transition in P2 at about 70 degrees C.
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Affiliation(s)
- I J Colquhoun
- Institute of Food Research, Norwich Research Park, Colney, UK
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Mountzouris KC, Gilmour SG, Jay AJ, Rastall RA. A study of dextran production from maltodextrin by cell suspensions of Gluconobacter oxydans NCIB 4943. J Appl Microbiol 1999; 87:546-56. [PMID: 10583683 DOI: 10.1046/j.1365-2672.1999.00850.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This study investigated dextran synthesis from a commercial maltodextrin substrate using cell suspensions of G. oxydans NCIB 4943 as catalysts. Experiments were arranged according to a central composite statistical design. The effects of substrate concentration (10-100 g l-1), cell concentration (0.32-32.0 g wet weight l-1), time of reaction (8-48 h) and pH (3.5-5.5), each at three levels, on dextran yield and dextran molecular weight (MW), were investigated. Response surface methodology was used to assess factor interactions, and empirical models describing the two responses were fitted. Most of the variance in dextran yield could be explained by the fitted model (R2 = 0.96). Dextran yield ranged from 1.21 to 41.69%. The presence of significant negative quadratic effects of cell concentration and time indicated that dextran yield reached a plateau and thus, optimum levels of cell concentration and time could be identified to maximize dextran yield. Dextran MW ranged from 6.6 to 38 kDa and was characterized by the significant interactions of reaction time with substrate concentration and cell concentration. The model, however, could account for only 60% of the variance in dextran MW. Possible reasons for this are discussed.
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Affiliation(s)
- K C Mountzouris
- Department of Food Science and Technology, University of Reading, Norwich, UK
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Ridout MJ, Brownsey GJ, Gunning AP, Morris VJ. Characterisation of the polysaccharide produced by Acetobacter xylinum strain CR1/4 by light scattering and atomic force microscopy. Int J Biol Macromol 1998; 23:287-93. [PMID: 9849626 DOI: 10.1016/s0141-8130(98)00057-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The molecular weight of the extracellular polysaccharide (CR1/4) produced by Acetobacter xylinum strain CR1/4 has been shown to be dependent upon growth conditions. Under normal growth conditions a high molecular weight polysaccharide ( > 1 x 10(6) Da) is produced. Maintaining the pH at 5 results in an order of magnitude increase in the total yield of polysaccharide, but also an order of magnitude decrease in molecular weight. Analysis of the CR1/4 polysaccharides by the techniques of atomic force microscopy and static light scattering suggests that they are double helices. In solution the molecules behave as stiff coils with a Kuhn statistical segment length of 325 nm.
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Affiliation(s)
- M J Ridout
- Food Biophysics Department, Institute of Food Research, Norwich Laboratory, Colney, UK
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Ridout MJ, Cairns P, Brownsey GJ, Morris VJ. Evidence for intermolecular binding between deacetylated acetan and the glucomannan konjac mannan. Carbohydr Res 1998; 309:375-9. [PMID: 9764469 DOI: 10.1016/s0008-6215(98)00149-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Binary mixtures of deacetylated acetan and konjac mannan form thermoreversible gels under conditions for which the individual components do not gel. Such synergistic behaviour is normally attributed to intermolecular binding between the two polysaccharides. X-ray diffraction data obtained from oriented fibres prepared from deacetylated acetan-konjac mannan gels provides direct evidence for intermolecular binding between the two polysaccharides. The novel heterotypic junction zones appear to be six-fold helices with a pitch of 5.6 +/- 0.1 nm.
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Affiliation(s)
- M J Ridout
- Department of Food Biophysics, Institute of Food Research, Norwich Research Park, Colney, Norwich, UK
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18
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Ridout MJ, Brownsey GJ, Morris VJ. Synergistic Interactions of Acetan with Carob or Konjac Mannan. Macromolecules 1998. [DOI: 10.1021/ma971631p] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- M. J. Ridout
- Institute of Food Research, Norwich Laboratory, Norwich Research Park, Colney, Norwich NR4 7UA, U.K
| | - G. J. Brownsey
- Institute of Food Research, Norwich Laboratory, Norwich Research Park, Colney, Norwich NR4 7UA, U.K
| | - V. J. Morris
- Institute of Food Research, Norwich Laboratory, Norwich Research Park, Colney, Norwich NR4 7UA, U.K
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Ojinnaka C, Brownsey GJ, Morris ER, Morris VJ. Effect of deacetylation on the synergistic interaction of acetan with locust bean gum or konjac mannan. Carbohydr Res 1997; 305:101-8. [PMID: 9534230 DOI: 10.1016/s0008-6215(97)00277-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
It has been discovered that deacetylation of the bacterial polysaccharide acetan promotes synergistic interactions with either locust bean gum (LBG) or konjac mannan (KM). Acetan is similar in structure to xanthan, and adopts a similar 5-fold conformation in the solid state. Like xanthan, it shows a thermally reversible order (helix)-disorder (coil) transition in solution. Both polymers have a cellulosic backbone with charged (anionic) sidechains attached at O-3 of alternate glucosyl residues, but the sidechains in acetan are longer (pentasaccharide rather than trisaccharide) and do not contain pyruvic substituents. Acetan has two sites of acetylation, one at O-6 of the inner mannosyl residue of the carbohydrate sidechains (as in xanthan) and the other on the polymer backbone (believed to be at O-6 of the branched glucosyl residues). Solutions of acetan or deacetylated acetan were equilibrated against 10 mM potassium chloride (to stabilise the ordered conformation) and were mixed (at 25 degrees C) with solutions of LBG or KM, also equilibrated against 10 mM potassium chloride. Unlike xanthan, native acetan showed no evidence of synergistic interaction with either LBG or KM. After deacetylation, however, large enhancements were observed in dilute-solution viscosity, and thermoreversible gels were formed at higher concentrations. With KM as co-synergist, gel melting was accompanied by an intense endotherm in differential scanning calorimetry. The magnitude of this endotherm increased with storage time at 25 degrees C, reaching a final value of delta H approximately 15.9 J/g (in comparison with delta H approximately 5.0 J/g for the order-disorder transition of deacetylated acetan alone). It is suggested that interaction occurs by formation of heterotypic junctions between the acetan backbone and unsubstituted regions of the plant polysaccharide, and that the acetate groups on native acetan promote solubility and hence inhibit association.
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Affiliation(s)
- C Ojinnaka
- Cranfield University, Silsoe College, Bedford, UK
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MacCormick C, Harris J, Jay A, Ridout M, Colquhoun I, Morris V. Isolation and characterization of a new extracellular polysaccharide from an Acetobacter species. J Appl Microbiol 1996. [DOI: 10.1111/j.1365-2672.1996.tb01935.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ojinnaka C, Jay AJ, Colquhoun IJ, Brownsey GJ, Morris ER, Morris VJ. Structure and conformation of acetan polysaccharide. Int J Biol Macromol 1996; 19:149-56. [PMID: 8910054 DOI: 10.1016/0141-8130(96)01120-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Acetan is an anionic bacterial polysaccharide. The chemical repeat unit consists of a cellobiose unit solubilised by attachment of a charged pentasaccharide sidechain to one of the glucose residues. The repeat unit contains two sites of acetylation. 1H and 13C NMR studies, coupled with both basic-methylation and mild-methylation studies, have shown that acetylation occurs at C6 on the (1,2)D-Man and the (1,34)D-Glc residues. A variety of techniques including NMR, optical rotation, circular dichroism and DSC show evidence for a thermoreversible conformational order (helix)-disorder (coil) transition for acetan in aqueous solution. The studies suggest that acetylation of the backbone does not prevent helix formation.
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Affiliation(s)
- C Ojinnaka
- Department of Food Science and Technology, Cranfield University, Silsoe College, Bedford, UK
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23
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Griffin AM, Morris VJ, Gasson MJ. Identification, cloning and sequencing the aceA gene involved in acetan biosynthesis in Acetobacter xylinum. FEMS Microbiol Lett 1996; 137:115-21. [PMID: 8935665 DOI: 10.1111/j.1574-6968.1996.tb08092.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The aceA gene from Acetobacter xylinum was identified and cloned from a genomic DNA library. The complete DNA sequence was determined and computer analysis of the translated gene sequence revealed homology with the deduced amino acid sequence of gumD from Xanthomonas campestris. Therefore aceA is likely to encode the phosphate-prenyl glucose l-phosphate transferase catalyzing the first step in acetan biosynthesis in A. xylinum.
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Affiliation(s)
- A M Griffin
- Institute of Food Research, Norwich Laboratory, Colney, UK. annette.griffin/b
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Colquhoun IJ, Defernez M, Morris VJ. NMR studies of acetan and the related bacterial polysaccharide, CR1/4, produced by a mutant strain of Acetobacter xylinum. Carbohydr Res 1995; 269:319-31. [PMID: 7780996 DOI: 10.1016/0008-6215(94)00367-o] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Acetan is a bacterial polysaccharide produced by Acetobacter xylinum NRRL B42. Chemical mutagenesis of A.xylinum allowed selection of a mutant strain which produced a new polysaccharide, CR1/4. 2D NMR methods have been used to assign the 1H and 13C spectra of the two polysaccharides and to determine that CR1/4 has the structure shown below. The total number of O-acetyl groups is slightly less than two per repeating unit. [formula: see text] The pentasaccharide side chain of acetan is truncated to a disaccharide unit in CR1/4, but the structures are otherwise identical. In particular, the degree of acetylation is about the same and the O-acetyl groups are located at the same position in both polysaccharides.
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Affiliation(s)
- I J Colquhoun
- Institute of Food Research, Norwich Laboratory, Norwich Research Park, Colney, United Kingdom
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25
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Gunning AP, Kirby AR, Morris VJ, Wells B, Brooker BE. Imaging bacterial polysaccharides by AFM. Polym Bull (Berl) 1995. [DOI: 10.1007/bf00423359] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Kirby AR, Gunning AP, Morris VJ, Ridout MJ. Observation of the helical structure of the bacterial polysaccharide acetan by atomic force microscopy. Biophys J 1995; 68:360-3. [PMID: 7711262 PMCID: PMC1281695 DOI: 10.1016/s0006-3495(95)80195-5] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A method has been developed that has been found to give reproducible images of uncoated polysaccharides by Atomic Force Microscopy (AFM). Aqueous solutions of the polysaccharide are deposited as drops onto freshly cleaved mica surfaces, air dried, and then imaged under butanol. The method has been used to obtain images of the bacterial polysaccharide acetan. In regions within the deposited sample, where the molecules are aligned side-by-side, it has been possible to observe a periodic structure along the polysaccharide chain, attributable to the helical structure of acetan.
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Affiliation(s)
- A R Kirby
- Institute of Food Research, Colney, Norwich, United Kingdom
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27
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Griffin AM, Morris VJ, Gasson MJ. Genetic analysis of the acetan biosynthetic pathway in Acetobacter xylinum. Int J Biol Macromol 1994; 16:287-9. [PMID: 7727341 DOI: 10.1016/0141-8130(94)90057-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We have identified, cloned and sequenced an 8422 base pair fragment of Acetobacter xylinum genomic DNA containing part of the acetan biosynthetic gene cluster. Computer analysis of the nucleotide sequence data generated revealed the presence of six open reading frames. Comparison of the translated sequences of putative genes to the amino acid sequences of genes from other organisms was used to assign functions to the aceA, aceC and manB genes. These genes were predicted to encode a UDP-glycosyl transferase, a GDP-mannosyl transferase and a phosphomannose isomerase/GDP-mannose pyrophosphorylase, respectively.
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Affiliation(s)
- A M Griffin
- Institute of Food Research, Norwich Laboratory, Colney, UK
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28
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Ridout MJ, Brownsey GJ, Morris VJ, Cairns P. Physicochemical characterization of an acetan variant secreted by Acetobacter xylinum strain CR1/4. Int J Biol Macromol 1994; 16:324-30. [PMID: 7727347 DOI: 10.1016/0141-8130(94)90064-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Chemical mutagenesis has been used to produce mutants of Acetobacter xylinum NRRL B42 that are cellulose-negative and that produce variants of the acetan structure deficient in the side-chain sugar residues. The product of A. xylinum strain CR1/4 has been shown to possess a tetrasaccharide repeat unit with the side chain terminating in glucuronic acid. X-ray diffraction studies of oriented fibres suggest that the polysaccharide CR1/4 forms a fivefold helix with a pitch of 4.8 nm. Light-scattering studies on CR1/4 solutions suggest a molecular weight of 1.2 x 10(6) with radii of gyration values of 86 nm (aqueous solution) and 67 nm (0.1 M NaCl solution). The magnitude of the measured radii of gyration and the shape of the Holtzer plots suggest that CR1/4 can be described as a stiff coil. Preliminary differential scanning calorimetry data show melting behaviour consistent with order-disorder transitions of a charged helical structure. Rheological studies have revealed new synergistic interactions of CR1/4 with locust bean gum. Comparative studies of acetan and CR1/4 show that decreasing the length of the side chain enhances the solution viscosity.
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Affiliation(s)
- M J Ridout
- Institute of Food Research, Norwich laboratory, Colney, UK
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Abstract
Sufficient well-characterized microbial exopolysaccharides are now available to permit extensive studies on the relationship between their chemical structure and their physical attributes. This is seen even in homopolysaccharides with relatively simple structures but is more marked when greater differences in structure exist, as are found in several heteropolysaccharides. The specific and sometimes unique properties have, in the case of several of these polymers, provided a range of commercial applications. The existence of "families" of structurally related polysaccharides also indicates the specific role played by certain structures and substituents; the characteristics of several of these microbial polysaccharide families will be discussed here. Thus, microbial exopolysaccharides frequently carry acyl groups which may profoundly affect their interactive properties although these groups often have relatively little effect on solution viscosity. Xanthan with or without acylation shows marked differences in synergistic gelling with plant gluco- and galacto-mannans, although the polysaccharides with different acylation patterns show similar viscosity. Similarly "gelrite" from the bacterium originally designated as Auromonas (Pseudomonas)elodea is of greater potential value after deacetylation, when it provides a valuable gelling agent, than it is as a viscosifier in the natural acylated form. The Klebsiella type 54 polysaccharide only forms gels when it, too, has been chemically deacetylated to give a structure equivalent to the Enterobacter XM6 polymer. Both these polysaccharides form gels due to the enhanced interaction with cations following deacylation and to the conformation adopted after removal of the acyl groups. Recent work in our laboratory suggests that deacetylation of certain bacterial alginates also significantly increases ion binding by these polysaccharides, making them more similar in their properties to algal alginates even although the alginates from some Pseudomonas species lack poly-L-guluronic acid sequences. The existence within families of polysaccharides of types in which monosaccharides are altered within a specific structure, or with varying side-chains, also gives an indication of the way in which such substituents affect the physical properties of the polymers in aqueous solution.
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Affiliation(s)
- I W Sutherland
- Institute of Cell and Molecular Biology, Division of Biology, University of Edinburgh, Scotland
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