Lactobacillus sobrius sp. nov., abundant in the intestine of weaning piglets.

ABSTRACT

To obtain porcine isolates related to Lactobacillus amylovorus, we screened strains from piglet intestine grown on Lactobacillus-specific MRS agar for hybridization to a fluorescent 16S rRNA-targeted DNA probe. Six strains were isolated and further characterized by phenotypic and molecular taxonomic methods. The isolates were Gram-positive, catalase-negative, facultatively anaerobic rods. They had similar phenotypic characteristics and displayed genomic DNA-DNA relatedness values of >78 % to each other, indicating that they belong to a single species. Comparative 16S rRNA gene sequence analysis demonstrated that the novel isolates were members of Lactobacillus rRNA group I, which includes Lactobacillus delbrueckii, the type species of the genus. Based on 16S rRNA gene sequence similarity, Lactobacillus kitasatonis (99 %), Lactobacillus crispatus (98 %) and Lactobacillus amylovorus (97 %) were the nearest relatives of the novel isolates, but their DNA-DNA relatedness was found to be lower than 49 %. One of the isolates, strain OTU171-001T, was further characterized using physiological and biochemical tests. Together, the results enabled genotypic and phenotypic differentiation of strain OTU171-001T from the other species that showed 16S rRNA gene sequence similarity values greater than 97 %. Strain OTU171-001T merits species status and the name Lactobacillus sobrius sp. nov. is proposed. The type strain is OTU171-001T (= DSM 16698T = NCCB 100067T).