Proposal of Lactobacillus kosoi Chiou et al. 2018 as a later heterotypic synonym of Lactobacillus micheneri McFrederick et al. 2018, elevation of Lactobacillus plantarum subsp. argentoratensis to the species level as Lactobacillus argentoratensis sp. nov., and Lactobacillus zhaodongensis sp. nov., isolated from traditional Chinese pickle and the intestinal tract of a honey bee (Apis mellifera)

Abstract

Lactobacillus kosoi Chiou et al. 2018 and Lactobacillus micheneri McFrederick et al. 2018 are closely related, and they share 100 % 16S rRNA gene sequence similarity, 99.6 % pheS gene sequence similarity, 100 % rpoA gene sequence similarity, 97.3 % average nucleotide identity (ANI) value and 76.6 % in silico DNA–DNA hybridization (isDDH) value, indicating that they represent the same species. Fatty acid methyl esters (FAME) analysis and phenotypic characterization also indicated that L. kosoi and L. micheneri are very similar. We propose L. kosoi Chiou et al. 2018 as a later heterotypic synonym of L. micheneri McFrederick et al. 2018. The taxonomic position of Lactobacillus plantarum subsp. argentoratensis in the L. plantarum group was re-examined using a polyphasic approach, including sequence analyses of 16S rRNA, pheS, rpoA and recA genes, average nucleotide identity analysis, in silico DNA–DNA hybridization, fatty acid methyl ester analysis and phenotypic characterization. Results of 16S rRNA gene sequence analysis indicated that L. plantarum subsp. argentoratensis was closely related to L. plantarum subsp. plantarum , L. pentosus and L. paraplantarum in the L. plantarum group, sharing 99.6–99.7 % 16S rRNA gene sequence similarities. Results of pheS, rpoA and recA gene sequence analyses indicated that L. plantarum subsp. argentoratensis was most closely related to L. plantarum subsp. plantarum , having 91.8 % pheS gene sequence similarity, 98.9 % rpoA gene sequence similarity and 93.1 % recA gene sequence similarity. L. plantarum subsp. argentoratensis DSM 16365T shared 95.6 % ANI value and 62.9 % isDDH value with L. plantarum subsp. plantarum ATCC 14917T. The low isDDH value confirmed that L. plantarum subsp. argentoratensis and L. plantarum subsp. plantarum represent two different species, rather than two different subspecies in the L. plantarum group. On the basis of the data from polyphasic characterization obtained in the present study and in previous studies, L. plantarum subsp. argentoratensis is elevated to the species level and represents a novel species of the genus Lactobacillus , for which the name Lactobacillus argentoratensis sp. nov. is proposed and the type strain is DKO 22T (=CIP 108320T=DSM 16365T=JCM 16169T). Two novel Gram-stain-positive bacterial strains, designated 1206-1T and F027-1-2, were isolated from traditional pickle in Heilongjiang Province, PR China, and from the intestinal tract of a honey bee (Apis mellifera) in Hubei Province, PR China, respectively. The two bacteria were characterized by a polyphasic approach, including 16S rRNA gene sequence analysis, pheS gene sequence analysis, rpoA gene sequence analysis, fatty acid methyl ester analysis, average nucleotide identity analysis, in silico DNA–DNA hybridization analysis and an analysis of phenotypic features. The results of 16S rRNA gene sequence analysis indicated that strains 1206-1T and F027-1-2 were distantly related to Lactobacillus sharpeae , Lactobacillus hulanensis , Lactobacillus songhuajiangensis , Lactobacillus pantheris , Lactobacillus thailandensis , Lactobacillus camelliae , Lactobacillus jixianensis , Lactobacillus nasuensis , Lactobacillus baoqingensis , Lactobacillus manihotivorans and Lactobacillus porcinae . Strain 1206-1T exhibited 94.2–96.4 % 16S rRNA gene sequence similarities, 69.5–83.3 % pheS gene sequence similarities and 73.1–90.3 % rpoA gene sequence similarities to type strains of phylogenetically related species. ANI and isDDH values between strain 1206-1T and the type strains of phylogenetically related species were 52.7–73.7 % and 21.1–30.1 %, respectively. On the basis of the data obtained in the present study, a novel species, Lactobacillus zhaodongensis sp. nov. is proposed and the type strain is 1206-1T (=CCM 8981T=CCTCC AB 2019200T=LMG 31620T).