Two novel Gram-stain-negative, aerobic, motile by gliding, bacterial strains, designated H375T and H407T, were isolated from freshwater in South Korea. To determine their taxonomic positions, the strains were fully characterized. Based on information, including 16S rRNA gene and draft genome sequences, both isolates (H375T and H407T) were found to belong to the genus Lacibacter. H375T shares the highest 16S rRNA gene similarity (99.2%) with Lacibacter sediminis S13-6-22T. In addition, H407T also shows (98.3%) 16S rRNA gene similarity with L. sediminis S13-6-22T. The draft genomes of strains H375T and H407T consisted of 5,079,137 and 4,865,722 bp, respectively, and had DNA G+C contents of 40.0 mol% and 40.7 mol%. The average nucleotide identity between H375T and H407T was 81.7%, and the digital DNA-DNA hybridization value was 24.5%, both below the species delineation threshold. Strains H375T and H407T possessed menaquinone-7 as the predominant respiratory quinone and their fatty acid profiles included C15:0 iso, C15:0 iso 3OH, C15:1 iso G, C17:0 iso 3OH and C16:1 ω7c/C16:1 ω6c (summed feature 3) as the major fatty acids, supporting their affiliation to the genus Lacibacter. The major known polar lipid in both novel isolates was phosphatidylethanolamine. Moreover, physiological and biochemical results allowed the phenotypic and genotypic differentiation of strains H375T and H407T from their closest and other species of the genus Lacibacter with validly published names. Therefore, H375T and H407T represented novel species of the genus Lacibacter, for which the names Lacibacter aquaticus sp. nov. (type strain H375T=KACC 23521T=LMG 33421T) and Lacibacter koreensis sp. nov. (type strain H407T=KACC 23522T=LMG 33422T) were proposed.
Keywords: 16S rRNA gene sequencing; Lacibacter aquaticus sp. nov.; Lacibacter koreensis sp. nov.; draft genome sequencing; polyphasic taxonomy.