Eight strains of Lactobacillus with identical partial 16S rRNA gene sequences and similar randomly amplified polymorphic DNA patterns were isolated from fermentation samples from Japanese and Scottish malt whisky distilleries. Phylogenetic analysis of almost complete 16S rRNA gene sequences from three representative strains (two from Japan, one from Scotland) placed them in the genus Lactobacillus as members of the Lactobacillus acidophilus group. Lactobacillus helveticus and Lactobacillus gallinarum were the most closely related species, with 16S rRNA gene similarities of 99.3 and 98.1 %, respectively. A similar phylogeny was derived from partial sequences of elongation factor Tu (tuf) genes in which the alleles from the three distillery isolates were identical and shared 99.0 % similarity with L. helveticus and L. gallinarum tuf genes. S-layer (slp) gene sequences suggested different relationships among the strains and the distillery isolates no longer formed a monophyletic group. The alleles from the Japanese and Scottish strains shared only 54 % similarity. Chromosomal DNA from the distillery strains gave DNA-DNA hybridization values between 79 and 100 % but showed less than 43 and 22 % reassociation with L. helveticus and L. gallinarum DNA, respectively. The name Lactobacillus suntoryeus sp. nov. is proposed for this novel taxon; the type strain is strain SAT (=LMG 22464T=NCIMB 14005T).