Lactobacillus rossii sp. nov. isolated from wheat sourdough

Abstract

Screening of sourdough lactic acid bacteria for bacteriocin production resulted in the isolation of a Gram-positive, catalase-negative, non-spore-forming, non-motile rod bacterium (strain CS1T ) that could not be associated with any previously described species. Comparative 16S rRNA gene sequence analysis recognized strain CS1T as a distinct member of the genus actobacillus. By a species-specific PCR strategy, five additional strains previously isolated from sourdoughs were found to belong to the same species as strain CS1T , as confirmed by 16S rRNA gene sequence analysis. The closest related species were Lactobacillus durianis, Lactobacillus malefermentans and Lactobacillus suebicus, with which strain CS1T shared 93 % sequence similarity. For a further characterization of strain CS1T physiological (growth temperature, CO2 production, hydrolysis of arginine, isomeric type of lactate, sugar fermentation) and chemotaxonomic (G+C content and peptidoglycan structure) properties were determined. Phenotypic characterization showed that strain CS1T was a member of the obligately heterofermentative group of the genus Lactobacillus. The DNA G+C content was 44?6 mol%. The peptidoglycan was of the A3a (L-Lys–L-Ser–L-Ala2) type. Physiological, biochemical and genotypic data, as well as results of DNA–DNA hybridization of genomic DNA with one of the closest hylogenetic relatives, L. durianis (34?3 %), indicated that strain CS1T represents a novel species of the genus Lactobacillus for which the name Lactobacillus rossii sp. nov. is proposed. The type strain of this species is CS1T (=ATCC BAA-822T =DSM 15814T).