A large test tube was charged with 5 ml of Medium A described hereinbefore and, after sterilization, inoculated with one of the microorganisms indicated in Table 1 and Table 2. Aerobic shake culture was carried out at 27° C. for 2 to 3 days. From a 1.5 ml portion of the resulting culture, the cells were harvested by centrifugation and suspended in 0.5 ml of 100 mM phosphate buffer (pH 6.5) containing 0.05% of (5S)-6-benzoyloxy-5-hydroxy-3-oxohexanoic tert-butyl ester and 8% of glucose. The suspension was put in a test tube equipped with a threaded stopper and the reaction was carried out under shaking at 27° C. for 20 hours. After the reaction, 4 volumes of ethyl acetate were added to the reaction mixture and after thorough mixing, the cells were centrifugally removed. The supernatant was analyzed by high-performance liquid chromatography for the amount of (3R,5S)-6-benzoyloxy-3,5-dihydroxyhexanoic tert-butyl ester produced per ml of the reaction mixture and the diastereomer ratio (=(3R,5S)/(3S,5S) ratio). The results are shown in Table 1 and Table 2.
