Production and characterization of a novel high-alkaline and thermal stable lipase from Bacillus sp. HCU3-2 and potential application as detergent formulation

Abstract

The focus of this study was on production, characterization and application of an extracellular lipase from Bacillus sp., isolated from soil. Thirty six 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. Therefore, a strain HCU3-2 was isolated as the best producer and finally identified as Bacillus sp. HCU3-2. The maximum lipase production was obtained palm fatty acid distillated from palm oil refining process at concentration of 2% (v/v) of basal medium (84.69 +- 0.48 U/mg), followed in order by wastewater from palm oil refining process (46.86 +- 0.75 U/mg). The higher lipase production was obtained when ammonium sulfate was used at concentration of 0.5% (v/v) of basal medium (90.71+-0.11 U/mg). The optimum temperature and pH for lipase production were 45 °C and pH 7, respectively. Zymogram assay of crude enzyme on SDS-PAGE presented one band with lipase activity of molecular weight of 66 kDa. The optimum pH and temperature for activity were pH 11 and 55 °C respectively. The enzyme was stable in the pH range 9-11 for 60 min and at 40-55 °C for 60 min. Higher activity was observed in the presence of surfactants, emulsifier, Ca2+, Mg2+, Zn2+ ions and strongly inhibited lipase activity by DTT. 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.