Companilactobacillus miaonis sp. nov. - a novel bacterium isolated from zha-chili

Two Gram-positive, rod-shaped bacteria, designated as strains HBUAS56257^T and HBUAS59544, were isolated from zha-chili. Both strains were found to be catalase-negative and facultatively aerobic. Moreover, both HBUAS56257^T and HBUAS59544 grew optimally at a temperature of 25-40 °C and a pH of 4-6 in the presence of 2-10% NaCl. The major fatty acids in these microbes were C_16:0 and C_18:1 ω9c, with intraspecific variations observed in the relative abundances of summed feature 7 and C19:0 iso. The DNA G+C contents were 36.06 mol% and 36.10 mol%, respectively. Based on 16S rRNA gene and other genomic sequences, HBUAS56257^T and HBUAS59544 were found to exhibit the closest relatedness to Companilactobacillus suantsaicola NBRC 113530^T and Companilactobacillus alimentarius DSM 20249^T. Phylogenetic analyses, based on both the 16S rRNA gene and 81 housekeeping genes, showed that the strains shared distinct phylogenetic lineages within the genus Companilactobacillus. Digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values indicated that strains HBUAS56257^T and HBUAS59544 belong to the same species. However, when compared to the type strains of other Companilactobacillus species, both dDDH and ANI values fell below the established prokaryotic species delineation thresholds (typically ≤70% for dDDH and ≤95-96% for ANI). Moreover, unlike the type strains of closely related species, HBUAS56257^T and HBUAS59544 fermented d-galactose and l-rhamnose. Based on these phenotypic, chemotaxonomic and phylogenetic data, we concluded that strains HBUAS56257^T and HBUAS59544 represent a novel species within the genus Companilactobacillus, hereby named Companilactobacillus miaonis sp. nov., with HBUAS56257^T (= KCTC 21229^T= GDMCC 1.4547^T) being the type strain of C. miaonis.