Aims: To isolate a new exopolysaccharide bioflocculant produced by the myxobacterium Sorangium cellulosum NUST06, and to characterize its chemical composition and expolysaccharide production relative to carbon source.
Methods and results: Exopolysaccharide levels and biomass production by S. cellulosum NUST06 were analysed relative to carbon source. Glucose in the medium at a level of 3 g l(-1) completely inhibited cell growth and exopolysaccharide production, but low concentrations of glucose (1-2 g l(-1)) could stimulate cell utilization of starch. The chemical composition and flocculating activity of the NUST06 exopolysaccharide was investigated. The flocculant comprised 38.3% proteins and 58.5% carbohydrates, of which glucose, mannose and glucuronic acid were present at 51.3%, 39.2% and 10.5%, respectively. The flocculating activity of the NUST06 flocculant depended strongly on cations.
Conclusions: It is feasible to produce an exopolysaccharide bioflocculant by the strain NUST06 in a mineral salts medium using starch as a carbon source.
Significance and impact of the study: This strain may be advantageous for commercial bioflocculant production and may enrich existing knowledge of myxobacteria.