Herein, response surface methodology (RSM) was employed to optimize the bioprocess parameters for improved production of extracellular lipase by Aspergillus melleus and evaluated its biocatalytic potential for degradation of polyester vylon-200. Our previous report showed that pH, incubation time, temperature, and additional nitrogen source had significant effects on lipase biosynthesis. The variance analysis revealed that the established RSM model based on a central composite design for lipase production was significant (p < 0.0001, R2 = 0.9925). Under the optimized bioprocess conditions of pH 5.68, incubation time 96 h, temperature 30 °C, and diammonium tartrate as a nitrogen source, maximum lipase titer of 1346.87 U/gds was achieved, 1.92-fold higher than lipase yield in basal medium. The optimally synthesized cell-free lipase extract was partially purified by ammonium sulfate fractionation and dialysis and used to degrade polyester vylon 200. The degradation profile revealed that the lipolytic enzyme demonstrated excellent hydrolytic potential resulting in a 76% weight of polyester vylon-200. Differential scanning calorimetry revealed a noticeable decrease in the glass transition temperature of PV-200 (from 72.6 ºC to 63.9 ºC). Scanning electron microscopy envisaged various micron-scale cracks and holes on the surface of film after enzymatic treatment. Likewise, significant weight loss of the PV-200 films was also corroborated by FTIR analysis. This study's findings illustrate lipase's potential as a green and ecofriendly biocatalyst for robust polyester degradation and depolymerization.

中文翻译：

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黄曲霉增强脂肪酶生物合成及其降解聚酯 Vylon-200 的生物催化潜力

在本文中，响应面法 (RSM) 被用于优化生物工艺参数，以提高蜂蜜曲霉生产胞外脂肪酶的能力，并评估其降解聚酯 vylon-200 的生物催化潜力。我们之前的报告表明，pH、孵育时间、温度和额外的氮源对脂肪酶的生物合成有显着影响。方差分析表明，基于脂肪酶生产的中心复合设计建立的 RSM 模型是显着的（p < 0.0001，R2 = 0.9925）。在pH 5.68、孵育时间96 h、温度30 °C、酒石酸二铵作为氮源的优化生物工艺条件下，达到了1346.87 U/gds的最大脂肪酶滴度，比基础培养基中的脂肪酶产量高1.92倍。最佳合成的无细胞脂肪酶提取物通过硫酸铵分馏和透析部分纯化，并用于降解聚酯 vylon 200。降解曲线显示脂肪分解酶表现出优异的水解潜力，导致聚酯 vylon-200 的重量为 76%。差示扫描量热法显示 PV-200 的玻璃化转变温度显着降低（从 72.6 ºC 到 63.9 ºC）。扫描电镜观察到酶处理后薄膜表面出现各种微米级的裂纹和孔洞。同样，FTIR 分析也证实了 PV-200 薄膜的显着重量损失。这项研究的结果表明脂肪酶作为一种绿色环保的生物催化剂具有强大的聚酯降解和解聚潜力。