Influence of growth conditions on production of capsular and extracellular polysaccharides byRhizobium leguminosarum |
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Authors: | M W Breedveld L P T M Zevenhuizen H C J Canter Cremers A J B Zehnder |
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Institution: | (1) Department of Microbiology, Agricultural University, Hesselink van Suchtelenweg 4, 6703 CT Wageningen, The Netherlands;(2) Institute of Plant Molecular Biology, State University of Leiden, Nonnensteeg 3, 2311 VJ Leiden, The Netherlands;(3) Present address: Department of Food Science, 101 Borland Laboratory, The Pennsylvania State University, 16802 University Park, PA, USA;(4) Present address: AHA, Zeemanstraat 35, 2912 BK Nieuwerkerk a/d IJssel, The Netherlands;(5) Present address: EAWAG/ETH, CH-8600 Dübendorf, Switzerland |
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Abstract: | The influence of growth rate and medium composition on exopolymer production byRhizobium leguminosarum was studied. When grown in medium containing 10g/l mannitol and 1g/l glutamic acid,Rhizobium leguminosarum biovartrifolii TA-1 synthesized up to 2.0g/l of extracellular polysaccharide (EPS), and up to 1.6g/l of capsular polysaccharide (CPS). Under non-growing cell conditions in medium without glutamic acid, CPS synthesis by strain TA-1 could proceed to 2.1g/l, while EPS-production remained relatively low (0.8g/l). Maximal CPS-yield was 2.9g CPS/l medium in a medium containing 20g/l mannitol and 2g/l glutamic acid. TheEPS-deficient strain R. leguminosarum RBL5515,exo4::Tn5 was able to produce CPS to similar levels as strain TA-1, but CPS-recovery was easier because of the low viscosity of the medium and growth of the cells in pellets. With strain TA-1 in nitrogen-limited continuous cultures with a constant biomass of 500mg cell protein/l, EPS was the most abundant polysaccharide present at every dilution rate D (between 0.12 and 0.02 h–1). The production rates were 50–100mg/g protein/h for EPS and 15–20mg/g protein/h for CPS. Only low amounts of cyclic -(1,2)-glucans were excreted (10–30 mg/l) over the entire range of growth rates.Abbreviations bv
biovar
- CPS
capsular polysaccharide
- EPS
extracellular polysaccharide
- HMr
high molecular mass
- LMr
low molecular mass
- YEMCR
Yeast Extract-Mannitol-Congo Red agar |
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Keywords: | capsular polysaccharide extracellular polysaccharide polysaccharide production Rhizobium leguminosarum |
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