Lactobacillus frumenti sp. nov., a new lactic acid bacterium isolated from rye-bran fermentations with a long fermentation period.

Abstract

Within the framework of the characterization of the microflora of an industrial sourdough fermentation, strains of Lactobacillus amylovorus, Lactobacillus pontis and two other strains were isolated which could not be associated with a valid species. These latter strains were Gram-positive, catalase-negative, non-spore-forming, non-motile rods that could be clearly differentiated from known species by 16S rDNA sequence analysis. For further characterization, the morphological, physiological (sugar fermentation, formation of DL-lactate, hydrolysis of arginine, growth temperature, CO2 production) and chemotaxonomic (G+C content, cell wall composition, SDS-PAGE of whole-cell proteins) properties were determined. Fitting of the complete 16S rDNA sequence into alignments of such sequences, together with the subsequent phylogenetic calculations, allowed the reconstruction of a phylogenetic tree. These data showed that the two strains were phylogenetically related but formed an independent cluster distinct from their closest neighbours, L. pontis, Lactobacillus panis, Lactobacillus oris, Lactobacillus vaginalis and Lactobacillus reuteri. The results of DNA-DNA hybridization experiments indicated that the two isolates represent a new Lactobacillus species, for which the name Lactobacillus frumenti is proposed; the type strain of this species is DSM 13145T (= LMG 19473T).