Abstract #M120

# M120
Screening of lipolytic, proteolytic, and antibacterial activities of lactic acid bacteria with biotechnological significance isolated from dairy products.
Israel García-Cano*1, Diana Rocha-Mendoza1, Joana Ortega-Anaya1, Rafael Jiménez-Flores1, 1The Ohio State University, Columbus, OH.

Fermented dairy products such as yogurt and cheese are an important source of high quality nutrients for consumers. The wide variety of fermented products, in terms of chemical composition, are the result of the metabolism of lactic acid bacteria (LAB). The predominant enzymes that contribute to the diversity of fermented dairy products include lipases, proteases, and antibacterial proteins such as bacteriocins and peptidoglycan hydrolases, which are synthesized directly by LAB having a high biotechnological importance. Microbiome studies based in metagenomics indicate that there are specific enzymes contributing to the fermentation process and bioavailability. The objective of this work was to identify and characterize strains of LAB that possess high enzymatic expression of lipolytic, proteolytic, or antibacterial activity. Additionally, we aimed to identify and localize the proteins involved in these processes; weather it takes place in the intra or extra cellular milieu to assess the potential application in the dairy industry. The LAB (131 strains) were identified by 16S DNA sequencing. The bacteria were grown in CGB medium and harvested by centrifugation at the end of the log phase. Both the pellet and the supernatant of each strain were tested for lipolytic, proteolytic, and antibacterial activity by agar diffusion and zymograms. Five genera of LAB were identified as most active; 2 of them showed lipolytic activity in the cell fraction, hydrolyzing tributyrin agar and a-naphthyl-acetate in zymography. The active enzyme was identified by LC/MS-MS as a phospholipase of 40 kDa. Other strains in the supernatant fraction showed 3 proteolytic enzymes (45, 60, and 75 kDa) hydrolyzing casein. The antibacterial activity by zymogram against M. lysodeikticus was found in the supernatant fraction. P. acidilactici was unique in possessing 1 bacteriocin and 2 peptidoglycan hydrolases with putative N-acetylmuramidase and N-acetylmuramoyl-l-alanine amidase activities. So far, 40, 56, and 65% of total strains showed proteolytic, lipolytic, and antibacterial activity, respectively. A significant value of this report is the characterization of these enzymatic activities and their relevance in their potential biological activity in dairy foods

Key Words: dairy product, bioactive compound, lactic acid bacteria