Phnomibacter ginsenosidimutans gen. nov., sp. nov., a novel glycoside hydrolase positive bacterial strain with ginsenoside hydrolysing activity.

ABSTRACT

The conversion of major ginsenosides into minor ginsenosides attracts a lot of interest because of their biological and pharmaceutical activities. Therefore, for the conversion of ginsenosides, finding a novel competent glycoside hydrolase-producing bacterial strain is useful for future research studies and the mass production of minor ginsenosides. Wastewater samples were collected and screened for novel glycoside hydrolase bacterial strains using Reasoner's 2A+aesculin agar medium. As a result, a novel glycoside hydrolase positive bacterial strain (SB-02T) was identified and subjected to a polyphasic taxonomic analysis. Based on genome analysis, strain SB-02T was found to be affiliated with the family Chitinophagaceae and have less than 92.8 % sequence similarity to other members of the same family. Functional analysis indicated that SB-02T was able to hydrolyse the ginsenosides Rb1, Rc and Rd to F2 and C-K. Due to the conversion of ginsenosides, the strain's genome was sequenced and the genes were annotated by the NCBI. The average amino acid identity and average nucleotide identity values between SB-02T and the available reference genomes were 65.7 and 65.9 %, respectively. The novel isolate contained MK-7 as the predominant menaquinone, the major polyamine putrescine, and iso-C15  0, iso-C15  1 G and iso-C17  0 3-OH as major fatty acids. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Thus, based on the data presented here, strain SB-02T represents a novel species within a new genus in the family Chitinophagaceae, for which the name Phnomibacter ginsenosidimutans gen. nov., sp. nov. is proposed. The type strain of Phnomibacter ginsenosidimutans is SB-02T (=KACC 21266T=LMG 31707T). The genome annotation of SB-02T shows many glycoside hydrolase genes, which may be responsible for the efficient production of many kinds of minor ginsenosides and will be very helpful for future research (target gene cloning) and mass production of either F2 or C-K.