High scleroglucan production by Sclerotium rolfsii:: Influence of medium composition

Scleroglucan production by Sclerotium rolfsii was markedly affected by the C-source concentration, showing a highest value with 150 g sucrose l(-1). Production was also influenced by the N-source, being considerably higher in media containing NO3- than in those containing NH4+, which had a clear inhibitory effect. Once defined the optimum culture medium composition, the highest exopolysaccharide production (ca. 26 g scleroglucan l(-1)) was achieved after 72 h of fermentation at shake flask scale. High values of yield (Y-p/c = 0.49), productivity (Pr = 0.365 g l(-1) h(-1)) and specific productivity (Pr/x = 0.031 g (g biomass)(-1) h(-1)) were observed, and productivity was 1.5 times further increased by scalling-up to fermenter scale. Addition of L-threonine, sunflower oil and ascorbic acid diminished exopolysaccharide production.