Abstract

Laccases are a group of oxidases that catalyze the oxidation of a wide range of electron rich substrates like phenolic compounds, lignin and aromatic amines. They are of interest because of their potential to be used in environmental and industrial applications. In this research, potent laccase producer fungi were screened and isolated from olive mill wastewater (OMW). One of the 23 isolated fungi was identified as Galactomyces geotrichum based on 18S rDNA sequence analysis that detected good laccase activity. Produced laccase had a molecular weight of 55 kDa that was confirmed by zymogram analysis. This is the first report about the optimization of laccase Production by G. geotrichum under solid-state fermentation. The optimization was made by the Taguchi design of experiments (DOE) methodology. An orthogonal array (L25) was designed using Minitab 19 software to study four effective process factors in five levels for laccase production. The optimum condition derived was; moisture content (80%), fermentation time (14 day), CuSO₄⋅5H₂O as the inducer (300 μM), glucose as a co-substrate (5 g/L). Maximum laccase activity of 52.86 (U/g of dry substrate) was obtained using optimum fermentation condition. This study aimed to better understand the laccase producing microorganisms in OMW and take them to OMW treatment that is rich in phenolic compounds.

摘要

漆酶是一组氧化酶，可催化多种富含电子的底物（如酚类化合物、木质素和芳香胺）的氧化。它们很受关注，因为它们具有用于环境和工业应用的潜力。在这项研究中，从橄榄磨废水 (OMW) 中筛选和分离了有效的漆酶生产真菌。根据检测到良好漆酶活性的 18S rDNA 序列分析，将 23 种分离的真菌中的一种鉴定为Galactomyces geotrichum。产生的漆酶的分子量为 55 kDa，经酶谱分析证实。这是关于G. geotrichum优化漆酶生产的第一份报告在固态发酵下。优化是通过田口实验设计 (DOE) 方法进行的。使用 Minitab 19 软件设计正交阵列 (L25) 以研究漆酶生产的五个级别的四个有效工艺因素。得出的最佳条件是；水分含量（80%），发酵时间（14 天），CuSO ₄ ⋅5H ₂ O 作为诱导剂（300 μM），葡萄糖作为共底物（5 g/L）。使用最佳发酵条件获得了 52.86（U/g 干底物）的最大漆酶活性。本研究旨在更好地了解 OMW 中产生漆酶的微生物，并将它们带到富含酚类化合物的 OMW 处理中。