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Taxonomic Study of the Lactobacillus acidophilus Group, with Recognition of Lactobacillus gallinarum sp. nov. and Lactobacillus johnsonii sp. nov. and Synonymy of Lactobacillus acidophilus Group A3 (Johnson et al. 1980) with the Type Strain of Lactobacillus amylovorus (Nakamura 1981)

Fujisawa, Tomohiko, Benno, Yoshimi, Yaeshima, Tomoko, Mitsuoka, Tomotari

International Journal of Systematic and Evolutionary Microbiology 1992; 42(3):487 · https://doi.org/10.1099/00207713-42-3-487

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Summary auto-generated

This taxonomic study examined the Lactobacillus acidophilus group using biochemical properties and DNA-DNA reassociation analysis. Researchers analyzed 52 strains isolated from humans and various animals, including chickens, pigs, and cattle. DNA-DNA homology testing revealed that strains previously classified as L. acidophilus actually comprised six distinct genomospecies. The study formally described two new species: Lactobacillus gallinarum sp. nov. (type strain ATCC 33199), primarily isolated from chicken intestines, and Lactobacillus johnsonii sp. nov. (type strain ATCC 33200), found in human and animal sources. Additionally, the researchers demonstrated that L. acidophilus group A3, previously described by Johnson et al., is synonymous with the already-established L. amylovorus. Phenotypic characteristics like carbohydrate fermentation patterns proved insufficient for species differentiation, making DNA-DNA homology testing essential. The study identified lactate dehydrogenase electrophoretic mobility and sodium chloride tolerance as useful differential phenotypic criteria distinguishing the new species from existing L. acidophilus group members.

Key findings

  • DNA-DNA reassociation studies demonstrated six distinct genomospecies within strains previously classified as Lactobacillus acidophilus, rather than a single species
  • Two new Lactobacillus species were formally described: L. gallinarum sp. nov. and L. johnsonii sp. nov., with specific type strains designated
  • L. acidophilus group A3 is synonymous with the previously described species L. amylovorus, clarifying taxonomic nomenclature
  • Phenotypic characteristics alone are inadequate for differentiating L. acidophilus genomospecies; DNA-DNA homology testing is necessary for accurate classification
  • Lactate dehydrogenase electrophoretic mobility and 4% NaCl tolerance serve as useful phenotypic markers for distinguishing the newly described species

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Abstract

Biochemical properties and DNA-DNA reassociation studies of Lactobacillus acidophilus strains isolated from humans and animals indicate that these include six genomospecies. Two new species can be differentiated from the established species of the genus Lactobacillus: L. gallinarum sp. nov. (type strain, ATCC 33199) and L. johnsonii sp. nov. (type strain, ATCC 33200). Furthermore, it was clarified that L. acidophilus group A3 (Johnson et al. 1980) is synonymous with L. amylovorus.