Significance and Impact of the Study: This is the first study to provide information of cultivable b-glycosidase-producing micro-organisms in ginseng field soil. The strain GS 09 has potential to be applied on the preparation for minor ginsenoside C-K in pharmaceutical industry. AbstractThis research aimed to explore the diversity of cultivable b-glycosidaseproducing micro-organisms in ginseng field soil. Fifty-three strains showing b-glucosidase activity were isolated from a ginseng field, using a newly designed Esculin-R2A agar. All the isolated strains belonged to the genus Agrobacterium, Arthrobacter, Burkholderia, Dyella, Edaphobacter, Luteibacter, Mucilaginibacter, Paenibacillus, Phenylobacterium, Pseudomonas, Sphingomonas and Streptomyces. The main b-glucosidase-producing micro-organisms in the ginseng field soil were Sphingomonas, Burkholderia, Luteibacter and Streptomyces, while concentrations of Agrobacterium, Arthrobacter, Paenibacillus and Pseudomonas were relatively low. Of these micro-organisms, the strain GS 09 could hydrolyse major ginsenosides Rb1, Rb2 and Rc to the active metabolite compound K. The strain GS 09 belonged to the genus Sphingomonas, and its 16S rRNA gene sequence showed 100% similarities with that of Sphingomonas asaccharolytica.

Rb₁ and Rg₁ are the major ginsenosides in protopanaxadiol and protopanaxatriol. Their content in ginsenosides was 23.8 and 17.6%, respectively. A total of 22 isolates of β-glucosidase producing microorganisms were isolated from the soil of a ginseng field using Esculin-R2A agar. Among these isolates, the strain GH21 showed the strongest activities to convert ginsenoside Rb₁ and Rg₁ to minor ginsenosides compound-K and F₁, respectively. Ginsenosides Rb₁ and Rg₁ bioconversion rates were 74.2 and 89.3%, respectively. Meanwhile, the results demonstrated that the ginsenoside Rg₁ could change the biotransformation pathway of ginsenoside Rb₁ by inhibiting the formation of the intermediate metabolite gypenoside-XVII. GH21 was identified as a Cladosporium cladosporioides species based on the internal transcribed spacers (ITS) ITS1-5.8S-ITS2 rRNA gene sequences constructed phylogenetic trees.

A total of 58 isolates of β-glucosidase-producing microorganisms were isolated from soil around the wild ginseng roots under forest using Esculin-R2A agar. Among these isolates, strain GS33 showed a strong ability to convert ginsenosides Rb1, Rb2, Rc, and Rd into F2, Rg3, C-K, and convert ginsenoside Rg1 into Rh1, and F1. Fermented ginseng products can inhibit ES-2 cells growth and the IC₅₀ value was 0.73 mg ml⁻¹. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain GS33 belongs to the genus Penicillium and is most closely related to Penicillium simplicissimum (99 %).

This is the first study to provide information of cultivable β-glycosidase-producing Endophytic fungus in Panax ginseng. The strain GE 17-18 has potential to be applied on the preparation for minor ginsenoside C-K in pharmaceutical industry.

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.