Evaluation of Fermentative Parameters for the Production of Botryosphaeran (a (1 -> 3;1 -> 6)-beta-D-glucan) and Mycelial Biomass by Botryosphaeria rhodina MAMB-05

Botryosphaeran is an exopolysaccharide (EPS) of the (1 -> 3; 1 -> 6)-beta-D-glucan type produced by the fungus Botryosphaeria rhodina MAMB-05. In attempts to enhance its extracellular production, the quantitative effects of different nitrogen sources, fermentation time, inoculum size, C/N ratio, and initial pH were evaluated on the yields of botryosphaeran. Ammonium nitrate was selected as the best nitrogen source in examining these effects using a 2(3)-factorial central-composite experimental design, and analysis by the response surface method. According to a factorial design, the most important variables influencing both botryosphaeran and mycelium biomass production was inoculum concentration and the time of growth. Under these conditions, optimum botryosphaeran production occurred at 88 h of growth, 0.88 g of mycelium L-1 of nutrient mediumat C/N ratio of 30, and resulted in a 5.2 g L-1 yield of EPS in the fermentation broth. For production of the mycelium biomass, the optimum condition occurred at the same time of growth and inoculum concentration; however the best C/N ratio was 75, and resulted in a yield of 33.8 g L-1 of biomass. The results also indicated that the maximal mycelial growth is not associated to the yields of botryosphaeran production by Botryosphaeria rhodina MAMB-05.