Molecular identification and optimization of lipase- producing strain Bacillus thuringiensis L26

Lipases are important hydrolytic enzymes produced by various microorganisms such as bacteria. This enzyme is applied in various industries including food and pharmaceutical industries. This study aimed to isolate and identify lipase-producing bacteria from various sources to use in different industries.

Sampling and screening of lipase- producing bacteria were carried out from wastewater and soils of Habib-abad refinery, wastewater and slugs of Golbahar oil factory, sheep’s tail fat, and sesame meal. To evaluate the enzymatic activity, bacterial isolates were cultured in lipid-based media, where the supernatant was used for the next assay. A quantitative assessment of enzymatic activity was performed using a spectrophotometer, in the presence of para-nitrophenol acetate at the temperature of 28°C. The identification of bacterial isolates was carried out by macroscopic, microscopic and molecular analysis.

Screening bacterial isolates and the results of enzymatic activity assays showed strain 31 as the superior one. Molecular analysis results identified this strain as Bacillus thuringiensis L26. The highest enzymatic activity and stability were obtained at the temperature of 48°C, pH value of 8.5, and in the presence of sodium chloride, calcium chloride, potassium chloride, magnesium chloride, zinc sulfate, and manganese chloride, respectively.

Our results showed the stability of tested lipase enzymes under alkaline conditions and the presence of different cations. Therefore, further complementary tests are recommended o assess practical uses.