Quality control Lactobacillus strains for use with the API 50CH and API ZYM systems at 37 degrees C.

The API 50CH and API ZYM systems fulfil an important role in the polyphasic taxonomic identification of lactobacilli. When the API 50CH fermentation profile of the quality control Lactobacillus casei var. alactosus (Lb. paracasei subsp. paracasei) strain NCFB 206 was determined at 37 degrees C, it was found to differ from that determined at 30 degrees C by BioMéreiux SA (Montalieu Vercieu, France) and the National Collection of Food Bacteria (Aberdeen, Scotland). In addition, the API 50CH fermentation and API ZYM profiles of Lb. casei strain ATCC 334T determined at 37 degrees C differed from those determined at 30 degrees C by Lee and Simard (1984). Strains NCFB 206 and ATCC 334T were thus assumed to exhibit temperature-dependent variation in fermentation profile, a phenomenon recently described by Nigatu et al. (2000). In contrast, Lb. rhamnosus strain ATCC 243T did not exhibit temperature-dependent variation in fermentation profile. Moreover, the fermentation profile obtained at 37 degrees C differed in only one respect (positive beta-gentiobiose utilisation) from that published by Collins et al. (1989). In addition, Lactobacillus strain GG produced a stable and reproducible API ZYM profile at 37 degrees C, although some variation in the level of enzyme activity was evident. Thus, strain NCFB 206 was replaced by strain ATCC 243T as the quality control strain of choice for use with the API 50CH fermentation system, and Lactobacillus strain GG adopted for use as a quality control strain with the API ZYM system for strain identification of lactobacilli at 37 degrees C. The API 50CH and API ZYM profiles of the commercially important Lactobacillus strains NCFB 1748, GG, KLD, F19, and ACA-DC 212.3 were determined at 37 degrees C after anaerobic growth in MRS broth. The fermentation and enzyme profiles of strain NCFB 1748 were almost identical to those of Lb. crispatus ATCC 33820T, those of strain GG were found to be more similar to those of Lb. rhamnosus strain 243T than Lb. zeae strain ATCC 15820T, those of strain KLD were most similar to those of Lb. fermentum DSM 20052T, while those of strains F19 and ACA-DC 212.3 were similar to those of Lb. casei strain ATCC 334T.