Biotransformation of ginsenoside Rb1 to ginsenoside Rd by highly substrate-tolerant Paecilomyces bainier 229-7

Paecilomyces bainier 229-7 was obtained after UV irradiation for 8 min in the presence of 0.4% LiCl and selection on potato dextrose media containing 30 mg/mL saponin from Panax notoginseng leaves (SPNL). The mutant produces ginsenoside Rd from ginsenoside Rb1 with a bioconversion rate as high as 94.9% under optimized culture conditions in shake flasks when supplied with 20 mg/mL of SPNL. Scale-up in 10-L fermenter resulted in an 89% bioconversion rate. Ginsenoside Rd was purified from the culture medium by a macroporous resin with a chromatographic purity of 92.6%. These results suggest that P. bainier 229-7 could be useful for the preparation of ginsenoside Rd in the pharmaceutical industry.