Lactobacillus secaliphilus sp. nov., isolated from type II sourdough fermentation

Two strains of Gram-positive, catalase-negative, lactic acid bacteria, strains TMW 1.1309(T) and TMW 1.1313, were isolated at an interval of several years from an industrial type II sourdough. They occurred at cell numbers of 8x10(8) c.f.u. g(-1) and therefore were considered to be one of the dominant members of the microbiota in this type of fermentation. Cells of both strains grow exclusively on modified MRS containing trypsin-digested rye-bran extract. Both strains possessed identical 16S rRNA gene sequences, but could be discriminated by RAPD fingerprints. Comparative 16S rRNA and tuf gene sequence analyses positioned strain TMW 1.1309(T) as part of the Lactobacillus reuteri phylogenetic group within the genus Lactobacillus. The 16S rRNA gene sequence similarities to the closest related species, Lactobacillus coleohominis and Lactobacillus ingluviei were 97.1 and 95.4 %, respectively. The DNA G+C content of strain TMW 1.1309(T) was 48 mol%. Growth characteristics, biochemical features and DNA-DNA hybridization values below 70 % with all the nearest neighbours demonstrated that the isolates represent a novel Lactobacillus species. The name Lactobacillus secaliphilus sp. nov. is proposed for the novel isolates, with the type strain TMW 1.1309(T) (=DSM 17896(T)=CCUG 53218(T)).