Isolation of Lactiplantibacillus plantarum producing Extracellular Lipase from Dairy Products and Optimization of the Enzyme Production

Abstract

Recently, microbial lipases isolated from probiotic bacteria have attracted the attention of many scientists because they have significantly beneficial properties for human health. As a highly nutritious substrate, dairy products possess great potential for probiotic bacteria isolation. The main purpose of this study was to isolate probiotic bacteria in order to search for lipase producing bacteria. The bacteria were isolated from dairy products and purified by repeated sub-culturing on MRS medium at 37°C. The isolates were subjected to primary and secondary screening via fluorometric and colorimetric methods respectively. The isolates showing orange fluorescence under UV light at 350 nm around their colonies were selected for the colorimetric method. In this method, lipase activity was investigated by p-nitrophenyl palmitate. Probiotic characterizations of lipase-producing isolates were performed by acid resistance test, cell surface hydrophobicity assay, auto-aggregation and co-aggregation. The optimization of lipase production was performed by Central Composite Design (CCD). In the present study, 92 isolates were recovered from 71 samples. The results showed that 41 isolates were positive for fluorometric assay. According to the amount of enzyme production, seven strains were selected for probiotic characterizations. Finally, a potential probiotic strain of genus Lactobacillus showed the highest enzyme activity with 3.4 U.ml-1 compared to other isolates. This strain showed 100% similarity to Lactiplantibacillus plantarum. This research indicated that the lipase of Lactiplantibacillus plantarum can be used as a promising enzyme in the food and medicine industries.