[Growth and lipolytic activity of Rhizopus microsporus at various cultivation temperatures]

The dynamics of growth and exolipase biosynthesis was studied in the fungus Rhizopus microsporus under laboratory and semi-industrial conditions at 28, 38 and 48 degrees C. As the temperature rises, the lag-phase as well as the exponential and stationary phases of growth are reduced while the specific growth rate increases. The accumulation of the biomass was found to correlate with the production of the enzyme which was most intensive at the end of exponential growth when the formation of spores was intensive. The greatest lipolytic activity of the cultural broth was recorded at the beginning of stationary growth of the culture. The lipolytic activity hardly changed at the stationary phase of growth and fell down abruptly when the cells died off. The temperature of 38 degrees C was optimal for the accumulation of biomass and lipase in the cultural broth. Good results were obtained at 28 degrees C, but the cultivation was prolonged by 5--7 hours. The yield of the biomass and the level of the lipolytic activity are much lower at 48 degrees C although the specific growth rate is high.