Production and Characterizations of Thermostable Alkaline Lipase from a Newly Isolated Pseudomonas SP. HCU2-1 Suitable for Detergent Formulation

Abstract

Lipase-producing bacteria were successfully isolated and selected thorough ecological niches and soil samples in which the activity was expected to be found. Thirty five bacterial strains were screened by activity on lipase test medium, and then further tested to determine their activity by using an agar plate containing tributyrin as an indicative substrate. Consequently, a strain HCU2-1 was isolated as the best produces and finally identified as Pseudomonas SP. HCU2-1. Lipase production by Pseudomonas SP. HCU2-1 was optimized by varying environmental and nutritional conditions. The maximum lipase production was obtained using wastewater from palm oil refining process at concentration of 2% (v/v) of basal medium (70.29+-).09 U/mg), followed in order by wastewater from soybean oil refining process (62.59+-0.38 U/mg) and crude acid oil from soybean oil refining process (62.48+-0.43 U/mg). respectively. The highest lipase activity (77.14+-0.33 U/mg) was obtained when peptone was used at concentration of 0.5% (v/v) of basal medium. The optimum temperature and pH for lipase production were 40 °C and pH 7, respectively. Zymogram assay of crude enzyme on SDS-PAGE presented one band with lipase activity of molecular weight of 45kDa. The optimum pH and temperature for activity were pH 11 and 60 °C, respectively. The enzyme was stable in the pH range 9-11 for 60 min and at 40-60 °C for 60 min. Higher activity was observed in the presence of surfactants, Ca2+, Mg2+, Mn2+ ions and strongly inhibited lipase activity by DTT and PMSF. The enzyme exhibited significant stability in the presence of commercial detergents and oxidizing agents. The remarkable resistance capability of the lipase makes it a potential additive for detergent formulation and other industrial applications.