Summary auto-generated
This study describes the identification and characterization of Lactobacillus equi sp. nov., a previously unknown lactic acid bacterium isolated from horse feces. Researchers collected fecal samples from 20 thoroughbred horses across multiple Japanese farms and isolated 178 Gram-positive rod colonies. Using DNA fingerprinting and DNA-DNA hybridization, they identified 18 strains from 10 horses that were distinct from known Lactobacillus species. These strains shared >80% DNA homology with each other but <30% with reference strains, and had a G+C content of 38-40 mol%. The organisms are facultatively anaerobic, catalase-negative, homofermentative rods that produce both D- and L-lactic acid. Phylogenetic analysis of 16S rRNA gene sequences revealed the closest relative to be Lactobacillus agilis (96.3% sequence homology), but the new isolates were biochemically and genetically distinct. The study established L. equi as a predominant member of the horse intestinal microbiota. The type strain YIT 0455T was deposited in multiple culture collections.
Key findings
- Lactobacillus equi sp. nov. is a new bacterial species isolated from feces of healthy horses, representing a predominant intestinal lactobacillus in this host
- 18 strains isolated from 10 of 20 horses examined shared >80% DNA-DNA homology with each other but <30% with all known Lactobacillus reference strains
- 16S rRNA gene sequencing showed L. equi was most closely related to L. agilis (96.3% identity) but was biochemically and genetically distinct
- L. equi is a facultatively anaerobic, homofermentative rod with G+C content of 38-40 mol% that produces both D- and L-lactic acid from glucose
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Abstract
Lactobacillus equi sp. nov. is described on the basis of 18 strains isolated as one of the predominant intestinal lactobacilli from horse faecal specimens. These 18 strains were isolated from 10 horses of 6 different farms out of 20 horses of 10 farms examined. They were Gram-positive, facultatively anaerobic, catalase-negative, non-spore-forming, non-motile, lactic-acid-homofermentative rods. The DNA G+C content was 38.9 +/- 0.8 mol%. DNA--DNA hybridization failed to associate these strains closely with any of the validly described type strains used. Analysis of the 16S rRNA gene sequence of representative strain YIT 0455(T) revealed that the new isolates represent a new Lactobacillus species, for which the name Lactobacillus equi is proposed. The type strain is YIT 0455(T) (=ATCC BAA-261(T)=JCM 10991(T)).