Selectivity in citric acid production by Yarrowia lipolytica

This experimental study reports about production selectivity in the fermentation of glucose to citric acid by Yarrowia lipolytica as a function of substrate concentration. Batch runs featuring biomass growth and one or two citric acid production phases were carried out in a 15-1 stirred tank fermenter. The presented results demonstrate that working at high initial substrate concentration in the production phase is beneficial both in terms of a higher production rate of citric acid, the desired metabolite (reaching 0.077 h(-1)) and of a higher utilization degree of the employed carbon source (yield up to 0.384 g(c.a)/g(glucose)). The production rate of isocitric acid, the major undesired metabolite, was found to be practically constant over the tested initial substrate concentration range. (C) 2001 Elsevier Science Inc. All rights reserved.