초록
<B>Abstract</B><P>The kinetics of continuous citric acid (CA) fermentation, using two acetate-negative mutants of Yarrowia lipolytica (Wratislavia AWG7 and Wratislavia 1.31) with long-term cell recycle, were investigated at a dilution rate (D) of 0.011 h−1. The capacity of the mutants to produce CA from raw glycerol under steady state conditions was compared. The process involving the Wratislavia AWG7 strain showed that this strain was a better producer of CA than the Wratislavia 1.31 strain in this regime. In steady state, the concentration of CA in the effluent was constant and amounted to 116 g dm−3. This corresponded to a volumetric CA production rate of 1.3 g dm−3 h−1. A stable high-level production of CA was maintained for over 400 h of operation. The Wratislavia AWG7 strain employed remained highly stable throughout the experiment and demonstrated good viability, high genetic and phenotypic stability over the long-term continuous fermentation process.</P>