Identification of Mucilaginibacter conchicola sp. nov., Mucilaginibacter achroorhodeus sp. nov. and Mucilaginibacter pallidiroseus sp. nov. and emended description of the genus Mucilaginibacter

Three chitinolytic, Gram-negative, light pink, capsule-forming, rod-shaped bacterial strains with gliding motion (MYSH2(T), MJ1a(T) and dk17(T)) were isolated from seashells, soil and foxtail, respectively. Phylogenetic analysis of the 16S rRNA gene sequences and concatenated alignment of 92 core genes indicated that strains MYSH2(T), MJ1a(T) and dk17(T) were novel species of the genus Mucilaginibacter and exhibited a high 16S rRNA sequence similarity (i.e. more than 97.2%) among each other. These novel strains contained summed feature 3 (C-16:1 omega 7c and/or C-16:1 omega 6), iso-C-15:0 and MK-7 as the predominant fatty acids and menaquinone. According to the CAZys coding gene of KAAS, MYSH2(T) and MJ1a(T) were interpreted as strains containing both GH18 and 19 family coding genes, except for dk17(T), which shows only GH19 family genes. These strains likely degrade chitin to chitobiose or directly to N-acetyl-d-glucosamine, which may enhance their chitinolytic capacity, thus making these stains potentially useful for industrial chitin degradation. Based on distinct morphological, physiological, chemotaxonomic and phylogenetic differences from their closest phylogenetic neighbours, we propose that strains MYSH2(T), MJ1a(T) and dk17(T) represent three novel species in the genus Mucilaginibacter, for which the names Mucilaginibacter conchicola sp. nov. (=KACC 19716(T)=JCM 32787(T)), Mucilaginibacter achroorhodeus sp. nov. (=KACC 19906(T)=NBRC 113667(T)) and Mucilaginibacter pallidiroseus sp. nov. (=KACC 19907(T)=NBRC 113666(T)) are proposed. An emended description of the genus Mucilaginibacter is proposed.