CHROMATOGRAPHIC PROFILING OF AMINOPEPTIDOLYTIC ACTIVITIES IN LACTOBACILLI AS A TOOL FOR STRAIN IDENTIFICATION

Lactobacillus helveticus andLt. delbrueckii subsp. bulgaricus produce a large range of peptidases which together are capable of degrading caseins into amino acids required by the bacteria (El Soda&Desmazeaud, 1982; Hickey et al. 1983; Law&Kolstad, 1983). Their aminopeptidases have been studied because of their potential use as mediators of cheese peptidolysis during maturation (Frey et al. 1986; Ardo et al. 1989). In Lb. helveticus three aminopeptidolytic activities with different substrate specificities were separated chromatographically (Ardo et al. 1989). In a strain of Lb. delbrueckii subsp. bulgaricus Atlan et al. (1989) found evidence for at least four aminopeptidases and one x-prolyldipeptidyl aminopeptidase. Peterson et al. (1990) found aminopeptidase profiling to be a useful method for the identification of Lactobacillus strains isolated from ripened cheese. They determined the specific activities against different substrates in crude cell-free extracts and carried out cluster analysis. Our intention was to develop a method to distinguish different strains of Lb. helveticus and Lb. delbrueckii subsp. bulgaricus with respect to properties of possible importance for cheese ripening. A chromatographic separation of the aminopeptidolytic activities before determination of the specificities was expected to add further information of value for the identification of Lactobacillus strains. © 1994, Proprietors of Journal of Dairy Research. All rights reserved.