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 p rofile of the quality control Lactobacillus casei var. alactosus (Lb. parac asei subsp. paracasei) strain NCFB 206 was determined at 37 degreesC, it wa s found to differ from that determined at 30 degreesC by BIOMEREIUX SA (Mon talieu Vercieu, France) and the National Collection of Food Bacteria (Aberd een, Scotland). In addition, the API 50CH fermentation and API ZYM profiles of Lb. casei strain ATCC 334T determined at 37 degreesC differed from thos e determined at 30 degreesC by LEE and SIMARD (1984). Strains NCFB 206 and ATCC 334T were thus assumed to exhibit temperature-dependent variation in f ermentation 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 pro file obtained at 37 degreesC differed in only one respect (positive beta -g entiobiose utilisation) from that published by Collins et al. (1989). In ad dition, Lactobacillus strain GG produced a stable and reproducible API ZYM profile at 37 degreesC, although some variation in the level of enzyme acti vity 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 fermentatio n 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 degreesC. The API 50CH and API ZYM profiles of the commercially importa nt Lactobacillus strains NCFB 1748, GG, KLD, F19, and ACA-DC 212.3 were det ermined at 37 degreesC after anaerobic growth in MRS broth. The fermentatio n 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 simila r to those of Lb. rhamnosus strain 243T than Lb. zeae strain ATCC 15820T, t hose 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. ca sei strain ATCC 334T.