The Gram-negative, strictly aerobic, non-motile, non-spore-forming, rod shaped bacterial strain designated $TR6-03^T$ was isolated from compost, and its taxonomic position was investigated by using a polyphasic approach. Strain $TR6-03^T$ grew at $4-42^{circ}C$ and at pH 6.0-8.0 on R2A and nutrient agar without NaCl supplement. Strain $TR6-03^T$ had ${eta}$-glucosidase activity, which was responsible for its ability to transform ginsenoside Re (one of the dominant active components of ginseng) to $Rg_2$. On the basis of 16S rRNA gene sequence similarity, strain $TR6-03^T$ was shown to belong to the family Sphingobacteriaceae and to be related to Mucilaginibacter lappiensis $ANJLI2^T$ (96.3% sequence similarity), M. dorajii $FR-f4^T$ (96.1%), and M. rigui $WPCB133^T$ (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 $C_{16:1}$ ${omega}7c$ and/or iso-$C_{15:0}$ 2OH), iso-$C_{15:0}$ and iso-$C_{17:0}$ 3OH. DNA and chemotaxonomic data supported the affiliation of strain $TR6-03^T$ to the genus Mucilaginibacter. Strain $TR6-03^T$ 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 $TR6-03^T$ (=KACC $14956^T$ =KCTC $12642^T$ =LMG $23497^T$).