Microbial enzyme systems for lignin degradation and their transcriptional regulation

Lignocellulosic biomass is the most abundant renewable resource in nature and has received considerable attention as one of the most promising alternatives to oil resources for the provision of energy and certain raw materials. The phenolic polymer lignin is the second most abundant constituent of this biomass resource and has been shown to have the potential to be converted into industrially important aromatic chemicals after degradation. However, due to its chemical and structural nature, it exhibits high resistance toward mechanical, chemical, and biological degradation, and this causes a major obstacle for achieving efficient conversion of lignocellulosic biomass. In nature, lignin-degrading microorganisms have evolved unique extracellular enzyme systems to decompose lignin using radical mediated oxidative reactions. These microorganisms produce a set of different combinations of enzymes with multiple isozymes and isoforms by responding to various environmental stimuli such as nutrient availability, oxygen concentration and temperature, which are thought to enable effective decomposition of the lignin in iignocellulosic biomass. In this review, we present an overview of the microbial ligninolytic enzyme systems including general molecular aspects, structural features, and systematic differences in each microorganism. We also describe the gene expression pattern and the transcriptional regulation mechanisms of each ligninolytic enzyme with current data.

木质素降解菌株产木质素降解酶的研究

采用液体静止培养,通过对分离筛选获得的两株高效木质素降解菌株15-1和14-7的发酵产木质素酶条件进行优化,得出结论:两株菌的最佳碳源均为稻草,最佳氮源均为尿素,最佳温度均为30℃。在最佳培养条件下进行发酵产酶,测得14-7的木素过氧化物酶和锰过氧化物酶活力分别为0.350 U.mL-1和0.080 U.mL-1;而15-1的木素过氧化物酶和锰过氧化物酶活力分别为0.300 U.mL-1和0.072 U.mL-1。

木质素降解复合菌的选育及其对芦苇浆卡伯值的影响

筛选木质素降解菌株并从中挑出产漆酶(Lac)和锰过氧化物酶(MnP)能力较强的4株菌株,复合培养得到4种复合菌ABC,ACD,ABD和BCD.复合培养后Lac和MnP产酶高峰较单一培养均有所提前,ABC,ACD的Lac和MnP酶活力活在60~72 h达到最大.BCD的Lac和MnP酶活力均高于其他3种,而且其MnP有两个产酶高峰.芦苇浆经4种复合菌处理后,卡伯值均有所下降,经BCD处理后卡伯值降幅最大,达到(5.3±0.12).

1株木质素降解菌的筛选、鉴定及液态发酵条件优化

【目的】制作应用于园林绿化废弃物的以木质素降解菌为原材料的高效液体菌剂。【方法】通过苯胺蓝平板褪色圈法和愈创木酚平板变色圈法从分离纯化得到的22株菌中筛选目标菌株,并用内转录间隔区(ITS)测序法对目标菌株进行鉴定,然后通过单因素试验对目标菌株的培养时间、接种量和培养基配方(碳源和氮源)进行优化,最后根据单因素试验结果,采用均匀实验结合人工神经网络算法寻找目标菌株的最佳发酵条件。【结果】根据平板褪色和显色结果,选定菌株Q01为目标菌株。经鉴定,菌株Q01为栓菌属Trametes真菌。根据单因素试验和均匀试验结果,确定菌株Q01的最优发酵条件为培养时间5 d,接种菌液体积分数为12.5%;培养基配方为木质素磺酸钠14.00 g·L^(-1)、蛋白胨12.30 g·L^(-1)、酵母粉5.00 g·L^(-1)、豆饼粉3.00 g·L^(-1)、五水合硫酸铜0.12 g·L^(-1)、氯化钠0.53 g·L^(-1)、pH自然。优化条件后菌株Q01的生物量提高1.27倍,锰过氧化物酶活性提高31.71倍,木质素过氧化物酶活性提高19.12倍,漆酶活性略有降低,但3种木质素酶的总酶活性提高了4.38倍。【结论】菌株Q01在优化后的发酵条件下制得的液体菌剂具有高酶活性和高生物量的特点,在降解园林绿化废弃物木质素方面具有一定应用潜力。图6表3参29。

木质素降解酶系染料降解原理概述

染料废水因染料本身的特性,无法通过传统的污水治理方法对废水内的染料进行降解,使得染料废水往往直接被排放,对生态环境造成恶劣影响,而染料本身所具有的生物毒性也有可能影响附近居民的身体健康,这也使得染料废水处理成为目前水污染控制难以解决的问题之一.木质素降解酶系可以有效降解多类有机污染物,为工业废水处理工作提供了新的思路与方法.本文简要介绍了木质素降解酶系的 产生、构成以及其降解原理,并从漆酶、锰过氧化物酶以及木质素过氧化物酶三个方面分别分析了木质素降解酶系对染料的降解原理,以期明确木质素降解酶系在染料废水治理工作中的价值.