Diaminobutyricibacter tongyongensis gen. nov., sp. nov. and Homoserinibacter gongjuensis gen. nov., sp. nov. Belong to the Family Microbacteriaceae

Two bacterial strains, KIS66-7T and 5GH26-15T, were isolated from soil samples collected in the South Korean cities of Tongyong and Gongju, respectively. Both strains were aerobic, Gram-stain-positive, mesophilic, flagellated, and rodshaped. A phylogenetic analysis revealed that both strains belonged to the family Microbacteriaceae of the phylum Actinobacteria. The 16S rRNA gene sequence of strain KIS66-7T had the highest similarities with those of Labedella gwakjiensis KSW2-17T (97.3%), Cryobacterium psychrophilum DSM 4854T (97.2%), Leifsonia lichenia 2SbT (97.2%), Leifsonia naganoensis JCM 10592T (97.0%), and Cryobacterium mesophilum MSL-15T (97.0%). Strain 5GH26-15T showed the highest sequence similarities with Leifsonia psychrotolerans LI1T (97.4%) and Schumannella luteola KHIAT (97.1%). The 16S rRNA gene sequence from KIS66-7T exhibited 96.4% similarity with that from 5GH26-15T. Strain KIS66-7T contained a B2γ type peptidoglycan structure with D-DAB as the diamino acid; MK-13, MK-12, and MK-14 as the respiratory quinones; ai-C15:0, ai-C17:0, and i-C16:0 as the major cellular fatty acids; and diphosphatidylglycerol, phatidylglycerol, and glycolipids as the predominant polar lipids. Strain 5GH26-15T had a B2β type peptidoglycan structure with D-DAB as the diamino acid; MK-14 and MK-13 as the respiratory quinones; ai-C15:0, i-C16:0, and ai-C{vn17:0} as the major cellular fatty acids; and diphosphatidylglycerol, phatidylglycerol, and glycolipids as the predominant polar lipids. Both strains had low DNA-DNA hybridization values (<40%) with closely related taxa. Based on our polyphasic taxonomic characterization, we propose that strains KIS66-7T and 5GH26-15T represent novel genera and species, for which we propose the names Diaminobutyricibacter tongyongensis gen. nov., sp. nov. (type strain KIS66-7T=KACC 15515T=NBRC 108724T) and Homoserinibacter gongjuensis gen. nov., sp. nov. (type strain 5GH26-15T=KACC 15524T=NBRC 108755T) within the family Microbacteriaceae.