Optimization, Purification and Characterization of Lipase from Streptomyces sp. A3301, with Application of Crude Lipase for Cooking Oily Wastewater Treatment

Abstract

Streptomyces sp. A3301, which produces lipase isolated by Panyachanakul et al. [1]. This optimization was done for the subsequent purification and characterization of the biological lipase produced by the isolate. The results showed that the strain produced lipase with a maximum activity of 321 U/mL using the optimal medium and conditions (1.5 % (w/v) xylose and 2 % (w/v) yeast extract, pH 7.0 at 30 °C, 150 rpm for 3 days). The specific activity of the purified lipase was 27,000 U/mg, which was 544 times the pre-purification level, based on hydrophobic chromatography. After ion-exchange chromatography, the specific activity was 5,600 U/mg, which was 113 times the pre-purification level, with a single-peak purification profile. The purified lipase had a single band based on SDS-PAGE analysis and the molecular mass was 45 kDa. The optimum temperature and thermo-stability of A3301 lipase were 60 and 30-55 °C, respectively. The optimum pH of the purified enzyme was pH 9.0, and the enzyme was stable in the pH range of 8.0-9.0. The purified lipase was stable in acetone, chloroform and toluene, with a high relative activity of 63-76 %. The immobilized strain was then applied to oily-wastewater treatment. The strain can remove oil and grease in synthetic wastewater containing oil at 1-3 % (v/v), with removal rates of 100, 99.82 and 99.68 %, respectively, after incubation for 6 days. It was then applied to oily-wastewater treatment from a restaurant, achieving the highest degradation rates of 98.53 % after treatment for 6 days. In addition, it also affected the Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) values decreasing.