A NEW IMMOBILIZED CELL METHOD, SILICONE-IMMOBILIZED CELLS USED IN PREPARATION OF CHIRAL INTERMEDIATES

The silicone-immobilized Geotrichum sp. G38 was used in the reduction of benzil to (S)-benzoin. The effects of stannous octanoate content, e thyl silicate content, water content and entrapped cell mass on the ac tivity of the immobilized cells were studied. The optimum pH value and temperature of the reaction medium were 7.0, 35 degrees C (free cells ) and 40 degrees C (immobilized cells), respectively. The immobilized cells showed higher activity than free cells under optimum conditions. The extent of conversion remained greater than 90% when the immobiliz ed cells were recycled 28 times.