Lactobacillus paragasseri sp. nov., a sister taxon of Lactobacillus gasseri, based on whole-genome sequence analyses

Int J Syst Evol Microbiol. 2018 Nov;68(11):3512-3517. doi: 10.1099/ijsem.0.003020. Epub 2018 Sep 18.


Three strains, JCM 5343T, JCM 5344 and JCM 1130, currently identified as Lactobacillus gasseri, were investigated using a polyphasic taxonomic approach. Although these strains shared high 16S rRNA gene sequence similarities with L. gasseri ATCC 33323T (99.9 %), they formed a clade clearly distinct from ATCC 33323T based on whole-genome relatedness. The average nucleotide identity and in silico DNA-DNA hybridization values of these three strains compared to L. gasseri ATCC 33323T were 93.4-93.7 and 53.1-54.1 %, respectively, and both were less than the widely accepted threshold to distinguish two species (95 and 70 %, respectively). The three strains were Gram-stain positive, non-motile, non-spore-forming, catalase-negative and rod-shaped bacteria. They grew at 25-45 °C and in the presence of 2.0 % (w/v) NaCl. The major fatty acids of the three strains were C16 : 0 and C18 : 1 ω9c. Based on phylogenetic analyses of the phenylalanyl-tRNA synthase alpha subunit and RNA polymerase alpha subunit genes, and on phenotypic and chemotaxonomic characteristics, strains JCM 5343T, JCM 5344 and JCM 1130 represent a novel species distinct from L. gasseri, for which we propose the name Lactobacillusparagasseri sp. nov. In addition, a large portion of genomes currently labelled as L. gasseri in the public sequence database should be reclassified as L. paragasseri based on whole-genome relatedness.

Keywords: Lactobacillus gasseri; Lactobacillus paragasseri.

MeSH terms

  • Bacterial Typing Techniques
  • DNA, Bacterial / genetics
  • DNA-Directed RNA Polymerases / genetics
  • Fatty Acids / chemistry
  • Genome, Bacterial*
  • Lactobacillus / classification*
  • Lactobacillus / genetics
  • Lactobacillus gasseri
  • Nucleic Acid Hybridization
  • Phylogeny*
  • RNA, Ribosomal, 16S / genetics
  • Sequence Analysis, DNA


  • DNA, Bacterial
  • Fatty Acids
  • RNA, Ribosomal, 16S
  • DNA-Directed RNA Polymerases
  • RNA polymerase alpha subunit