Description of Vagococcus coleopterorum sp. nov., isolated from the intestine of the diving beetle, Cybister lewisianus, and Vagococcus hydrophili sp. nov., isolated from the intestine of the dark diving beetle, Hydrophilus acuminatus, and emended description of the genus Vagococcus.

A polyphasic taxonomic approach was used to characterize two novel bacterial strains, HDW17A and HDW17B, isolated from the intestine of the diving beetle Cybister lewisianus, and the dark diving beetle Hydrophilus acuminatus, respectively. Both strains were Gram-positive and facultative anaerobic cocci forming cream-colored colonies. The isolates grew optimally at 25°C, pH 7, in the presence of 0.3% (wt/vol) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences and genome sequences showed that the isolates were members of the genus Vagococcus, and strain HDW17A was closely related to Vagococcus fessus CCUG 41755 (98.9% of 16S rRNA gene sequence similarity and 74.3% of average nucleotide identity [ANI]), whereas strain HDW17B was closely related to Vagococcus fluvialis NCFB 2497 (98.9% of 16S rRNA gene sequence similarity and 76.6% of ANI). Both strains contained C, and Cω9c as the major cellular fatty acids, but Cω9c was also observed only in strain HDW17B as the major cellular fatty acid. The respiratory quinone of the isolates was MK-7. The major polar lipid components were phosphatidylglycerol, phosphatidylethanolamine, and diphosphatidylglycerol. The genomic DNA G + C content of strains HDW17A and HDW17B were 36.6 and 34.4%, respectively. Both strains had cell wall peptidoglycan composed of the amino acids L-alanine, glycine, D-glutamic acid, L-tryptophan, L-lysine, and L-aspartic acid, and the sugars ribose, glucose, and galactose. Based on phylogenetic, phenotypic, chemotaxonomic, and genotypic analyses, strains HDW17A and HDW17B represent two novel species in the genus Vagococcus. We propose the name Vagococcus coleopterorum sp. nov. for strain HDW17A (= KACC 21348 = KCTC 49324 = JCM 33674) and the name Vagococcus hydrophili sp. nov. for strain HDW17B (= KACC 21349 = KCTC 49325 = JCM 33675).