Intracellular enzyme activities and autolytic properties of Lactobacillus acidophilus and Lactobacillus gasseri

A number of fermented milk products containing Lactobacillus acidophilus and Lactobacillus gasseri are now available as probiotic products. The proteolytic, lipolytic and autolytic properties of human-derived L. acidophilus (5 strains) and L. gasseri (7 strains) were evaluated, as these factors are closely related to cell viability and flavor development in the products. All L. gasseri strains showed higher intracellular protease activities than the L. acidophilus strains ; in contrast, lipase activities in L. gasseri were mostly lower than those of L. acidophilus. The many strains of L. gasseri were shown to have a greater tendency than L. acidophilus to autolyze in dispersed solution ; this liability was more distinct at lower pH values. These properties should be taken into account when bacteria are selected for production of probiotic products.