Glucosamine content of tempe mould, Rhizopus oligosporus

The glucosamine content of Rhizopus oligosporus NRRL 2710 mycelium grown in different media was determined. In Sabouraud dextrose broth the glucosamine content ranged from 51 g (kg dry biomass)(-1) for mycelial pellets less than 5 mm diameter to 107 g kg(-1) for pellets 16-35 mm diameter. Mycelium grown on Sabouraud dextrose agar contained 111 g glucosamine (kg dry biomass)(-1) while that grown on soymilk agar, used to simulate growth on soybeans in tempe, contained 82 g kg(-1). The estimation of glucosamine was reproducible, with a mean coefficient of variation of 4% for mycelial pellets and 11% for mycelium from agar media. It is suggested that a conversion factor of 12 g dry biomass (g glucosamine)(-1) is applicable to determine fungal biomass in tempe fermentation.