Characterization of lipases and preliminary purification of tributyrinesterases from lactic acid bacteria strains belonging to the Enterococcus and Lactococcus genera

The objective of this study is to characterize and attempt to purify lipolytic enzymes derived from strains of Enterococcus and Lactococcus genera isolated from various environments. For this purpose, ten strains of lactic acid bacteria were studied for their lipolytic and esterasic activities on an MRS (Man, Rogosa, and Sharpe) medium containing natural and/or artificial lipid substrates. Among them, two strains: Lactococcus lactis subsp lactis and Lactococcus lactis subsp cremoris showed maximum extracellular lipolytic activity in the presence of 1% olive oil. It was observed that both strains exhibited higher lipolytic activity at pH 7 and 8, with an optimal temperature of 30 °C and 37 °C, respectively. Glucose was found to be the best carbon source for both tested strains. The study of growth kinetics and fatty acid production over time revealed that fatty acid production begins during the exponential phase and reaches its maximum during the stationary phase. The purification of tributyrinesterases was carried out on two strains of Enterococcus genus: Enterococcus feacium and Enterococcus durans through ammonium sulfate precipitation and Sephadex G-100 gel filtration chromatography allowed the estimation of the molecular weight of the tributyrinesterases as 32.09 kDa and 38.49 kDa for both strains, respectively.