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).

Currently, Lactococcus lactis contains four subspecies: L. lactis subsp. lactis , L. lactis subsp. hordniae , L. lactis subsp. cremoris and L. lactis subsp. tructae . In the study of Pérez et al., these four subspecies could be clearly divided into two groups based on recA sequence analysis: L. lactis subsp. lactis and L. lactis subsp. hordniae ; L. lactis subsp. cremoris and L. lactis subsp. tructae . The two groups had a relatively low DNA–DNA hybridization value (about 60 %). In the present study, the taxonomic position of L. lactis subsp. cremoris and L. lactis subsp. tructae was re-examined based on sequence analyses of 16S rRNA, rpoB, recA and pheS genes, average nucleotide identity (ANI) values and digital DNA–DNA hybridization (dDDH) values. The result of 16S rRNA gene sequence analysis indicated that L. lactis subsp. cremoris NCDO 607T and L. lactis subsp. tructae L105T were phylogenetically related to the type strains of L. lactis subsp. hordniae , L. lactis subsp. lactis , Lactococcus taiwanensis , Lactococcus kimchii , Lactococcus allomyrinae , Lactococcus protaetiae, Lactococcus hircilactis , Lactococcus fujiensis and Lactococcus nasutitermitis . The 16S rRNA gene, rpoB, recA, pheS and concatenated rpoB, recA and pheS sequence similarities, ANI values, and dDDH values between the type strains of L. lactis subsp. cremoris , L. lactis subsp. tructae and phylogenetically related species were 93.5–99.4 %, 83.3–97.6 %, 80.6–92.4 %, 79.7–92.7 %, 83.5–94.3 %, 72.4–86.9 % and 21.4–32.5 %, respectively. Lower than 95–96 % ANI values and lower than 70 % dDDH values confirmed that the type strains of L. lactis subsp. cremoris and L. lactis subsp. tructae represent a novel species in the genus Lactococcus . Because L. lactis subsp. cremoris was proposed and validated before L. lactis subsp. tructae , L. lactis subsp. cremoris is elevated to the species level as Lactococcus cremoris sp. nov. and L. lactis subsp. tructae is transferred to L. cremoris as L. cremoris subsp. tructae comb. nov. The type strain of L. cremoris sp. nov. is NCDO 607T (=ATCC 19257T=DSM 20069T=JCM 16167T=LMG 6897T=NBRC 100676T). The type strain of L. cremoris subsp. tructae comb. nov. is L105T (=NBRC 110453T=DSM 21502T=JCM 31125T=LMG 24662T).

Four Gram-stain-positive bacterial strains were isolated from the gut of honeybee (Apis mellifera) in China. These strains were characterized using a polyphasic taxonomic approach. The data demonstrated that three of the four strains represented two novel species of the genus Lactobacillus , strains F306-1T and F551-2T were designated as the type strains. Results of 16S rRNA gene sequence analysis indicated that strains F306-1T, F447 and F551-2T were phylogenetically related to the type strains of Lactobacillus kimbladii and Lactobacillus kullabergensis , having 99.1–99.7 % 16S rRNA gene sequence (about 1400 bp) similarities. The phylogenetic tree based on concatenated pheS, rpoA, gyrB, hsp60, recA, rpoB and tuf sequences (4114 bp) and the phylogenomic tree based on whole genome sequences indicated that strains F306-1T and F447 were most closely related to L. kullabergensis Biut2NT, and strain F551-2T was most closely related to L. kimbladii Hma2NT. Strains F306-1T and F447 shared 99.9 % average nucleotide identity (ANI), 99.7 % digital DNA–DNA hybridization (dDDH) and 99.9 % average amino acid identity (AAI) values, indicating that they belong to the same species. Strain F306-1T exhibited the highest ANI (94.4 %), dDDH (56.7 %) and AAI (94.7 %) values to L. kullabergensis Biut2NT. Strain F551-2T had the highest ANI (94.0 %), dDDH (54.3 %) and AAI (95.8 %) values with L. kimbladii Hma2NT. Acid production from amygdalin, maltose, starch, gentiobiose and turanose, activity of esterase (C4) and α-glucosidase, growth with 3 % NaCl at 37 °C under strict anaerobic condition (on mMRS agar plates), and growth with 1–6% NaCl at 37 °C under aerobic condition (on mMRS agar plates supplemented with 0.05 % cysteine or with 1 % cysteine and 2 % fructose) could differentiate strains F306-1T and F447 from L. kullabergensis DSM 26262T. Acid production from d-glucose, arbutin and gentiobiose, growth with 3 % NaCl at 37 °C under strict anaerobic condition (on mMRS agar plates), and growth at 45 °C under strict anaerobic condition (on mMRS agar plates) could differentiate strain F551-2T from L. kimbladii DSM 26263T. Based upon the data obtained in the present study, two novel species, Lactobacillus huangpiensis sp. nov. and Lactobacillus laiwuensis sp. nov., are proposed and the type strains are F306-1T (=LMG 32144T=JCM 34361T=CCTCC AB 2020300T) and F551-2T (=JCM 34502T=CCTCC AB 2021027T), respectively.

A novel bifidobacteria (designated S053-2T) was isolated from the gut of honeybee (Apis mellifera). Strain S053-2T was characterized using a polyphasic taxonomic approach. The result of 16S rRNA gene sequence analysis indicated that strain S053-2T was phylogenetically related to the type strains of Bifidobacterium asteroides , Bifidobacterium indicum , Bifidobacterium actinocoloniiforme , Bifidobacterium xylocopae , Bifidobacterium coryneforme , Bifidobacterium apousia , Bifidobacterium choladohabitans and Bifidobacterium polysaccharolyticum , and had 95.5–99.7 % 16S rRNA gene sequence similarities. Based on the 16S rRNA gene sequence analysis, strain S053-2T was most closely related to the type strain of B. asteroides , having 99.7 % 16S rRNA gene sequence similarity. Strain S053-2T had relatively low (91.6–95.7 %) pheS, atpA, clpC, dnaG, fusA, glnA, glyS, hsp60, argS, pyrG and recA sequence similarities to the type strain of B. asteroides . Strain S053-2T had 94.5–95.3% atpA, clpC, dnaG, dnaK and pyrG sequence similarities to the type strain of B. apousia . The phylogenomic tree indicated that strain S053-2T belonged to the B. asteroides group, and was most closely related to the type strains of B. asteroides , B. apousia , B. choladohabitans and B. polysaccharolyticum , and distantly related to type strains of other phylogenetically related species in the B. asteroides group. Strain S053-2T shared the highest average nucleotide identity (ANI, 93.8 %), digital DNA–DNA hybridization (dDDH, 52.4 %) and average amino acid identity (AAI, 95.6%) values with B. apousia W8102T. Strain S053-2T shared 91.1 % ANI, 41.9 % dDDH and 92.5 % AAI values with B. asteroides DSM 20089T. Acid production from l-arabinose, d-xylose, d-mannose, amygdalin, cellobiose, maltose, melibiose, sucrose, raffinose, gentiobiose and l-fucose, and activity of esterase lipase (C8) and α-fucosidase could differentiate strain S053-2T from B. asteroides DSM 20089T. Acid production from d-mannose, maltose, sucrose, melezitose and gentiobiose, and activity of α-fucosidase could differentiate strain S053-2T from B. apousia W8102T. Based upon the data obtained in the present study, a novel species, Bifidobacterium mizhiense sp. nov., is proposed, and the type strain is S053-2T (=JCM 34710T=CCTCC AB 2021129T).

Three Gram-stain-positive bacterial strains (designated F502-1T, F575-4T and F582-1) were isolated from the gut of honeybee (Apis mellifera). These strains were characterized using a polyphasic taxonomic approach. Results of 16S rRNA gene sequence analysis indicated that strain F502-1T was phylogenetically related to the type strains of Apilactobacillus kunkeei , Apilactobacillus nanyangensis and Apilactobacillus apinorum , having 98.7–99.9 % 16S rRNA gene sequence similarities, 84.6–92.5 % pheS sequence similarities and 95.2–99.0 % rpoA sequence similarities, and that strains F575-4T and F582-1 were closely related to the type strain of Apilactobacillus ozensis , having 99.7 and 99.4 % 16S rRNA gene sequence similarities, respectively. Strains F575-4T and F582-1 had less than 88.7 % pheS and 96.4 % rpoA sequence similarities to strain F502-1T and type strains of all Apilactobacillus species. The average nucleotide identity and digital DNA–DNA hybridization values between strains F502-1T, F575-4T, F582-1 and type strains of all Apilactobacillus species were less than 91.3 and 43.5 %, respectively, confirming that they represent two novel species within the genus Apilactobacillus . Based upon the data obtained in the present study, two novel species, Apilactobacillus zhangqiuensis sp. nov. and Apilactobacillus xinyiensis sp. nov., are proposed and the type strains are F502-1T (=JCM 34500T=CCTCC AB 2021026T) and F575-4T (=JCM 34501T=CCTCC AB 2021028T), respectively.