Abstract

The Gram-negative, strictly aerobic, non-motile, non-spore-forming, rod shaped bacterial strain designated TR6-03T was isolated from compost, and its taxonomic position was investigated by using a polyphasic approach. Strain TR6-03T grew at 4-42°C and at pH 6.0-8.0 on R2A and nutrient agar without NaCl supplement. Strain TR6-03T had β-glucosidase activity, which was responsible for its ability to transform ginsenoside Re (one of the dominant active components of ginseng) to Rg2. On the basis of 16S rRNA gene sequence similarity, strain TR6-03T was shown to belong to the family Sphingobacteriaceae and to be related to Mucilaginibacter lappiensis ANJLI2T (96.3% sequence similarity), M. dorajii FR-f4T (96.1%), and M. rigui WPCB133T (94.1%). The G+C content of the genomic DNA was 45.6%. The predominant respiratory quinone was MK-7 and the major fatty acids were summed feature 3 (comprising C16:1 ω7c and/or iso-C15:0 2OH), iso-C15:0 and iso-C17:0 3OH. DNA and chemotaxonomic data supported the affiliation of strain TR6-03T to the genus Mucilaginibacter. Strain TR6-03T could be differentiated genotypically and phenotypically from the recognized species of the genus Mucilaginibacter. The isolate therefore represents a novel species, for which the name Mucilaginibacter composti sp. nov. is proposed, with the type strain TR6-03T (=KACC 14956T =KCTC 12642T =LMG 23497T).

• Keywords: 16S rRNA gene; polyphasic taxonomy; Mucilaginibacter composti; ginsenoside