A comparative study on batch and fed-batch cultures of oleaginous yeast Cryptococcus sp in glucose-based media and corncob hydrolysate for microbial oil production

The production of microbial lipids by a batch or fed-batch culture of oleaginous yeast was compared using glucose and corncob hydrolysate as carbon sources. Batch cultures using 4% (w/w) glucose as the carbon source reached a dry biomass, lipid yields and cellular lipid content of 9.4 g/l, 6.0 g/l and 63.5% (w/w), respectively. However, batch cultures demonstrated that there was an inhibitory effect on the biomass and lipid yields when the glucose concentration increased up to 6% (w/w). It was found that the fed-batch culture diminished the substrate's inhibition of microbial lipid-accumulation. Fed-batch cultures in the corncob hydrolysate-based media containing an initial 4% reducing sugar and an addition 2% glucose for 4 d of cultivation resulted in dry biomass and cellular lipid content of 10.8 g/l and 61.3% (w/w), respectively. The overall lipid productivity increased to 1.08 g/l/d for the fed-batch culture with an initial 4% glucose in corncob hydrolysate and an addition of corncob hydrolysate containing 2% glucose. High concentrations of reducing sugar in the corncob hydrolysate can be efficiently and rapidly converted to Cryptococcus lipid in the fed-batch culture system. Therefore, microbial lipids from Cryptococcus sp. are prospects for a potential alternative oil resource for biodiesel production. (C) 2012 Elsevier Ltd. All rights reserved.