Proteolytic profiles and angiotensin-I converting enzyme and alpha-glucosidase inhibitory activities of selected lactic acid bacteria.

This study was conducted to examine the growth, proteolytic profiles as well as angiotensin-I converting enzyme (ACE) and alpha-glucosidase (alpha-glu) inhibitory potentials of selected strains of lactic acid bacteria (LAB). Two strains each of yogurt bacteria (Streptococcus thermophilus-1275 and 285, and Lactobacillus delbrueckii ssp. bulgaricus-1092 and 1368), and probiotics (L. acidophilus-4461 and 33200, and L. casei-2607 and 15286, and 1 strain of Bifidobacterium longum 5022), were cultivated in reconstituted skim milk (RSM) at 37 degrees C and their proteolytic profiles and ACE as well as alpha-glu inhibitory activities were determined. Among all the strains of lactic acid bacteria studied, yogurt bacteria grew very well, with the exception of L. delbrueckii ssp. bulgaricus 1368 which showed a slower growth during the initial 3 h of incubation. The growth pattern corresponded well with the decrease in pH for the organisms. All the organisms showed an increase in proteolysis with time. The variations in proteolytic capabilities translated into corresponding variations in ACE inhibitory potential of these organisms. Bifidobacterium longum 5022 showed the highest ACE inhibitory potential followed by L. delbrueckii ssp. bulgaricus 1368, L. casei 15286, S. thermophilus 1275, and L. acidophilus 4461. Organisms with high intracellular enzymatic activities grew well. Also, aminopeptidases of strains of L. acidophilus 4461 and S. thermophilus 1275 that could better utilize proline containing substrates showed enhanced ACE inhibitory potential. Lactic acid bacteria possessed the ability to inhibit alpha-glu activity, which endowed them an antidiabetic property as well.