Feather degradation by Kocuria rosea in submerged culture

A strain of Kocuria rosea with keratinolytic activity was studied. In batch culture, the optimum temperature for feather degradation, bacterial growth and protease secretion was at 40 degreesC. A specific growth rate of 0.17 h(-1) was attained in basal medium with feathers as fermentation substrate. Under these conditions, after 36 h of incubation, biomass and caseinolytic activity reached 3.2 g/l and 0.15 U/ml, respectively. Extracellular protea se secretion was associated with the exponential growth phase. In batch fer mentation, feather degradation up to 51% in 72 h was obtained with a conver sion yield in biomass of 0.32 g/g. No organic acids were detected in the fe rmentation broth in significant amount.