The Lipase Activity from Moderately Halophilic and Halotolerant Microorganisms Involved in Bioconversion of Waste Glycerol from Biodiesel Industry

The waste glycerol representing the main secondary product in biodiesel industry is obtained in large amounts whose storage raise environmental problems. The bioconversion of this product to other product by various microorganisms represents a convenient alternative. Several enzymes are involved in waste glycerol conversion and among these the lipase has a great biotechnological importance. This work deals with the isolation, purification and kinetic characterization of lipase from moderately halophilic and halotolerant strains, namely Marinococcus halophilus JCM 2472 and strain S3-6. The purified enzyme showed catalytic activity at pH 8–10 and in a wide range of temperatures between 15 and 70 °C with optimum at values over 60 °C. The data recorded for the effect of sodium chloride content revealed the halotolerant character of the investigated enzymes with optimum activity at 1 M NaCl and being active between 0 and 3 M. The concentration of the substrate i.e. olive oil, sun-flower oil, has no effect on the lipase activity. The cultivation conditions of the microbial strains and the effect of culture media composition for obtaining the enzyme are also presented in this study.