The relatedness of the species Lactobacillus ingluviei and Lactobacillus thermotolerans was investigated by comparing partial sequences of the 16S rRNA gene (99.9 % similarity over 1504 bp), the hsp60 gene (98.8% similarity over 954 bp) and the recA gene (98.5% similarity over 452 bp) and by determining DNA-DNA binding levels (79 ± 3 %) and genomic DNA G + C contents (50 and 49 mol%, respectively). These data, in addition to their similar biochemical characteristics, suggest that the two taxa constitute a single species. According to Rules 38 and 42 of the Bacteriological Code, they should be united under the name Lactobacillus ingluviei, with the name Lactobacillus thermotolerans as a later heterotypic synonym.