Production of L-talitol from L-psicose by Metschnikowia koreensis LA1 isolated from soy sauce mash.

A strain LA1 that can convert L-psicose to L-talitol was isolated from soy sauce mash and identified as Metschnikowia koreensis. The cells grown on L-arabitol were found to have relatively high conversion potential. Addition of D-sorbitol to the reaction mixture considerably accelerated the conversion rate of L-psicose to L-talitol. During the conversion reaction, D-sorbitol was added to the reaction mixture at 12-h intervals to maintain the concentration of D-sorbitol at 1.0%. The final conversion ratios were 81.4%, 75.2%, 73.0%, 60.4% and 43.5% using washed cells when the concentrations of L-psicose were 0.5%, 1.0%, 2.0%, 3.0% and 5.0%, respectively. The product from L-psicose was identified as L-talitol by HPLC analysis, and infrared spectroscopy, optical rotation and melting point measurements.