Biotransformation of major ginsenosides into compound K by a new Penicillium dipodomyicola strain isolated from the soil of wild ginseng
A new strain, GH9, having ß-glucosidase activity was isolated from the soil of wild ginseng using Esculin-R2A agar. It shows the strongest activities to convert ginsenoside Rb1 to minor ginsenosides compound K. The transformation products were identified by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC), and strain GH9 was found to transform major ginsenoside to minor ginsenoside compound K as the key sole product. The optimal biotransformation conditions of GH9 with C-K were obtained as follows: media, yeast broth (YB); transforming temperature, 40°C; pH of the medium, 4 - 6; transforming time, 7 days. At these optimum conditions, the maximum yield was 86.1%. Strain GH9 was identified as a Penicillium dipodomyicola species based on the internal transcribed spacers (ITS) ITS1-5.8S-ITS2 rRNA gene sequences constructed phylogenetic trees.
Key words: Biotransformation, Panax ginseng, ginsenoside Rb1, ginsenoside compound K, minor ginsenoside.