Lentilactobacillus rapi subsp. dabitei subsp. nov., a lactic acid bacterium isolated from naturally fermented dairy product

Two lactic acid bacterial strains (IMAU80584T and IMAU92037) were isolated from naturally fermented dairy products (kurut and yoghurt) in China and Russia. Based on sequence analysis of the 16S rRNA gene it was revealed that these strains belonged to Lentilactobacillus rapi. However, phylogenetic tree analyses of two housekeeping genes, rpoA (encoding RNA polymerase alpha subunit) and pheS (encoding phenylalanyl-tRNA synthase alpha subunit), and 88 core genes, indicated the two strains were separated into an independent monophyletic branch from L. rapi DSM 19907T, forming an infra-specific subgroup. The average nucleotide identity and digital DNA-DNA hybridization values between IMAU80584T and L. rapi DSM 19907T were 93.1 and 52.8 %, respectively. Strains IMAU80584T and IMAU92037 are distinguished from L. rapi DSM 19907T because they have different polar lipids and fatty acids. The novel subgroup strains could not ferment gluconate potassium. The DNA G+C content of strain IMAU80584T was 42.3 mol%. The major cellular fatty acids were C16 : 0, C18 : 1 ω9t and summed feature 5 (C18 : 0 ante and/or C18 : 2 ω6c and/or C18 : 2 ω9c). Therefore, based on the results of polyphasic taxonomic analysis, IMAU80584T and IMAU92037 could be considered as a novel subspecies in the species L. rapi with the proposed name Lentilactobacillus rapi subsp. dabitei subsp. nov. The type strain is IMAU80584T (=GDMCC 1.2566T=JCM 34647T).