Abstract

The partially purified lipase from Aspergillus oryzae ST11 was immobilized on the surface-modified electrospun polyacrylonitrile (PAN) nanofibrous membrane. The effects of time and concentrations of glutaraldehyde and bovine serum albumin (BSA) were studied. The immobilized lipase reached the maximum activity at 180 min with the recovered activity of 44.2% (0.22 U/mg-support) in the absence of BSA. After adding 6 mg/mL BSA and 40 mM glutaraldehyde gave the recovered activity at 86.9% (0.43 U/mg-support). It showed the highest stability at pH 7.5 but the soluble lipase was at pH 7.0. In addition, the immobilized lipase was more stable at pH 4.0 and 9.0. The immobilized lipase preserved 56% activity at 70 °C but the soluble lipase had 34% activity. It conserved 86% activity while the soluble lipase had 18% activity after 13 days of storage at 4 °C. The operating parameters such as biocatalyst concentration, water content, and the molar ratio of methanol and palm oil were optimized for biodiesel production. The highest biodiesel conversion (95%) was obtained with the immobilized lipase 15% (w/w), 40% (w/w) 50 mM Tris-HCl buffer pH 7.0 and methanol/palm oil (3.5:1.0). This immobilized lipase could be reused with 82.9% conversion after 10 cycles of batch production.

摘要

来自米曲霉的部分纯化的脂肪酶ST11 固定在表面改性的电纺聚丙烯腈 (PAN) 纳米纤维膜上。研究了时间和戊二醛浓度和牛血清白蛋白 (BSA) 的影响。在不存在 BSA 的情况下，固定化脂肪酶在 180 分钟时达到最大活性，恢复活性为 44.2%（0.22 U/mg 支持物）。添加 6 mg/mL BSA 和 40 mM 戊二醛后，恢复活性为 86.9%（0.43 U/mg 载体）。它在 pH 7.5 下表现出最高的稳定性，但可溶性脂肪酶在 pH 7.0 下。此外，固定化脂肪酶在 pH 4.0 和 9.0 时更稳定。固定化脂肪酶在 70 °C 时保留了 56% 的活性，但可溶性脂肪酶具有 34% 的活性。在 4°C 下储存 13 天后，它保留了 86% 的活性，而可溶性脂肪酶具有 18% 的活性。为生物柴油生产优化了生物催化剂浓度、水含量以及甲醇和棕榈油的摩尔比等操作参数。使用固定化脂肪酶 15% (w/w)、40% (w/w) 50 mM Tris-HCl 缓冲液 pH 7.0 和甲醇/棕榈油 (3.5:1.0) 获得最高的生物柴油转化率 (95%)。这种固定化脂肪酶可以在 10 次批量生产循环后以 82.9% 的转化率重复使用。