Abstract

Using the statistical approach, this work seeks to optimize the process parameters to boost the generation of an organic solvent-tolerant lipase by Staphylococcus capitis SH6. The main parameters influencing the enzyme production were identified by using Plackett–Burman’s screening design. Among the test variables, only tryptone (25 g/L), malt extract (2.5 g/L), NaCl (10 g/L) and pH (7.0) contributed positively to enzyme production. Then, the crude lipase was immobilized by adsorption on CaCO₃ at pH 10. A maximum immobilization efficiency of 82% was obtained by incubating 280 mg of enzyme with CaCO₃ (1 g) during 30 min. The immobilized lipase was more stable toward organic solvents than the free enzyme. It retained about 90% of its original activity in the presence of ethanol and methanol. After that, the immobilized enzyme was used for biodiesel production by transesterification process between waste oil and methanol or ethanol during 24 h at 30 °C. Our results show that the lipase can be utilized efficiently in biodiesel industry. Likewise, we have demonstrated that the immobilized enzyme may be implicated in the biodegradability of waste grease; the maximum conversion yield into fatty acids obtained after 12 h at 30 °C, was 57%.

摘要

使用统计方法，这项工作旨在优化工艺参数，以促进头状葡萄球菌SH6产生耐有机溶剂脂肪酶。通过使用 Plackett-Burman 筛选设计确定影响酶生产的主要参数。在测试变量中，只有胰蛋白胨 (25 g/L)、麦芽提取物 (2.5 g/L)、NaCl (10 g/L) 和 pH (7.0) 对酶的产生有积极贡献。然后，粗脂肪酶通过吸附在 pH 10 的CaCO ₃上进行固定。通过将 280 mg 酶与 CaCO ₃一起孵育，获得了 82% 的最大固定效率(1 g) 在 30 分钟内。固定化脂肪酶对有机溶剂比游离酶更稳定。在乙醇和甲醇的存在下，它保留了大约 90% 的原始活性。之后，将固定化酶用于通过废油与甲醇或乙醇之间的酯交换过程在 30°C 下 24 小时生产生物柴油。我们的结果表明脂肪酶可以有效地用于生物柴油工业。同样，我们已经证明固定化酶可能与废油脂的生物降解性有关；在 30°C 下 12 小时后获得的脂肪酸的最大转化率为 57%。