Evaluation of the proteolytic activity of Enterococcus faecalis FT132 and Lactobacillus paracasei FT700, isolated from dairy products in Brazil, using milk proteins as substrates

Abstract

Lactic acid bacteria (LAB) have been used by mankind from immemorial times due to their technological properties and ability to improve sensorial properties of foods. Some LAB strains are also able to hydrolyze milk proteins, which increase their digestibility and contribute to the production of desirable flavors. Moreover, proteolytic activity of LAB on milk proteins may release bioactive peptides with different activities such as antihypertensive, antioxidant, antimicrobial, immunomodulatory and mineral-binding activities. This study aimed to evaluate the proteolytic activity of Enterococcus faecalis FT132 and Lactobacillus paracasei FT700, isolated from Brazilian dairy products. The proteolytic activity was checked by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and high-performance liquid chromatography using milk proteins as substrates in different conditions. Both E. faecalis FT132 and L. paracasei FT700 were proteolytic at pH 6.5 in the range of 37–42 °C, and these activities were due to metalloproteases. L. paracasei FT700 could then be used as adjunct culture in fermented dairy products in order to increase their digestibility. On the contrary, E. faecalis FT132, which harbors three virulence genes asa1, ace and gelE and which is resistant to erythromycin and tetracycline, cannot be added to food products. However, the peptides produced after hydrolytic activity on milk proteins by both strains might be used as ingredients in purified formulas.