Characterization of phytopathogen-preying Hyalangium versicolor sp. nov., and proposal for the reclassification of Cystobacter gracilis as Hyalangium gracile comb. Nov.

Abstract

A Gram-staining-negative, aerobic, and rod-shaped with tapered end myxobacterium, designed as strain H56D21T, was isolated from forest soil sampled from the Diaoluo Mountain National Nature Reserve located in Hainan Province, PR China. It showed prey ability on two kinds of phytopathogens including both fungi (Fusarium solani, Fusarium graminearum, andFusarium oxysporum) and bacteria (Ralstonia solanacearum and Xanthomonas campestris). Phylogenetic analyses based on the 16S rRNA gene and core genes sequencesrevealed that strain H56D21T belonged to the genus Hyalangium and was most closely related to Cystobacter gracilis DSM 14753T and Hyalangium minutum DSM 14724T. Genome comparison showed 85.6% and 82.3% ofaverage nucleotide identity between strain H56D21T and the above two type strains and 29.8% and 25.1%ofdigital DNA-DNA hybridization , respectively. The novel strain had a large genome size of 13.56 Mbp and a high DNAG + C content of 67.1%. Genome annotation identified 46 secondary metabolite biosynthesis gene clusters and 187 CAZymes-encoding genes. The major fatty acids contained iso-C15:0, iso-C15:0 DMA, C16:1 ω5c, and iso-C17:0. The dominant respiratory quinone was menaquinone 8. Based on the phenotypic, chemotaxonomic and phylogenetic analyses, we suggested that strain H56D21T should represent a novel species of the genus Hyalangium with a proposed name of Hyalangium versicolor sp. nov. (type strain H56D21T = GDMCC 1.1944T = KCTC 82613T) and Cystobacter gracilis should be reclassified as Hyalangium gracile comb. nov.