Mucilaginibacter polysacchareus sp. nov., an exopolysaccharide-producing bacterial species isolated from the rhizoplane of the herb Angelica sinensis

Abstract

Three exopolysaccharide-producing bacteria, designated strains DRP28T, DRP29 and DRP31, were isolated from the rhizoplane of Angelica sinensis from the Geumsan, Republic of Korea. Cells were straight rods, Gram reaction-negative, aerobic, non-motile, and catalase- and oxidase- positive. Flexirubin-type pigments were absent. Phylogenetic analysis of the 16S rRNA gene indicated that these bacteria belong to the genus Mucilaginibacter in the phylum Bacteroidetes. 16S rRNA gene sequence similarities to strains of recognized species of the genus Mucilaginibacter were 93.8–97.4 %. The major fatty acids were iso-C15 : 0 and summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH). The strains contained MK-7 as the major isoprenoid quinone. Strains DRP28T, DRP29 and DRP31 formed a single, distinct genomospecies with DNA G+C contents of 41.9–42.7 mol% and DNA hybridization values of 82.6–86.8 %; the strains exhibited DNA–DNA hybridization values of only 20.4–41.3 % with related species of the genus Mucilaginibacter. On the basis of evidence presented in this study, strains DRP28T, DRP29 and DRP31 were considered to represent a novel species of the genus Mucilaginibacter, for which the name Mucilaginibacter polysacchareus sp. nov. is proposed. The type strain is DRP28T ( = KACC 15075T  = NBRC 107757T).