Lipase Producing Strain And Its Application In The Production Of Bio-diesel

In this paper, screening of lipase-producing strains, optimization of fermentation conditions, immobilization of lipase and purification of the isolated G5 lipase were investigated.(1) Many lipase-producing strains were screened. Through a series of steps including plate isolation using olive oil as sole carbon source and Rhodamine B as indicator, flask fermentation and detection of transesterification activity to catalyze the production of biodiesel, one lipase-producing strain G5 with higher lipase activity was screened. The G5 strain was identified as Geotrichum sp. according to morphological observation. The properties of crude enzyme of this G5 lipase was also investigated. The optimum temperature and pH for this lipase were 40°C and 7.5, respectively, and the lipase showed high stability below 50°C and in the pH range of pH6.0⁸.0(2) Flask fermentation conditions of G5 lipase were optimized. The optimal conditions for the production of G5 lipase was as follows: 1.0 g sucrose, 2.0 g soybean powder, 0.5g peptone, 0.25g (NH₄)₂SO₄, 0.1g KH₂PO₄, 0.05g MgSO₄·7H₂O, 0.5 ml olive oil, 100ml water. The inoculated medium was incubated at 28 °C, 170rpm of rotation speed, 50ml medium in 300ml flask and 6(?)⁷2h of culture time.(3) Based on the optimal fermentation medium, effects of metal ions, addition of oils/fats on the growth and production of lipase were carried out. The results demonstrated that Mg²⁺ and Fe²⁺ was able to enhance the growth and production of lipase, Mg²⁺ showed the strongest enhancement effect, on the contrary, Na⁺, Mn⁺, Zn²⁺ showed inhibition effects, especially Mn²⁺ strongly inhibition production of this lipase. In the absence of oils/fats, lipases was rather low and lipase activity was promoted markedly by the addition of natural and synthetic oils/fats, olive oil was the best inductive composition for G5 lipase production.