API 50 CH fermentation profiles of 45 Lactobacillus, one Atopobium, and three Weissella strains incubated at 30 degrees C and 37 degrees C were evaluated. Atopobium uli and ten species of Lactobacillus showed stable patterns despite the change in temperature. The rest of the type strains showed discrepancy between the two incubation temperatures: 18 strains lost, 12 additionally fermented another sugar, and 7 others fermented a different one in lieu. The variation was maximum in L. delbrueckii subsp. delbrueckii. L. malefermentans failed to ferment any of the substrates at 37 degrees C. Majority of the food and plant-associated strains (mainly heterofermenters) retained distinctive traits at 30 degrees C, while most of the animal-associated strains (mostly homofermenters) did so at 37 degrees C. No general trend was observed; 30 degrees C appeared to promote heterofermentation, while 37 degrees C favored homofermenters. Use of API 50 CH profiles for taxonomic purpose in mast lactobacilli appears reproducible if a specific temperature for a species is strictly followed.