Department of Bioproducts and Biosystems Engineering, University of Minnesota, 2004 Folwell Ave., Saint Paul, MN, USA.
Appl Microbiol Biotechnol. 2010 May;86(6):1785-93. doi: 10.1007/s00253-010-2462-1. Epub 2010 Feb 23.
Brown rot fungi uniquely degrade wood by creating modifications thought to aid in the selective removal of polysaccharides by an incomplete cellulase suite. This naturally successful mechanism offers potential for current bioprocessing applications. To test the efficacy of brown rot cellulases, southern yellow pine wood blocks were first degraded by the brown rot fungus Gloeophyllum trabeum for 0, 2, 4, and 6 weeks. Characterization of the pine constituents revealed brown rot decay patterns, with selective polysaccharide removal as lignin compositions increased. G. trabeum liquid and solid state cellulase extracts, as well as a commercial Trichoderma reesei extract (Celluclast 1.5 L), were used to saccharify this pretreated material, using beta-glucosidase amendment to remove limitation of cellobiose-to-glucose conversion. Conditions varied according to source and concentration of cellulase extract and to pH (3.0 vs. 4.8). Hydrolysis yields were maximized using solid state G. trabeum extracts at a pH of 4.8. However, the extent of glucose release was low and was not significantly altered when cellulase loading levels were increased threefold. Furthermore, Celluclast 1.5 L continually outperformed G. trabeum cellulase extracts, although extent of glucose release never exceeded 22.0%. Results suggest methodological advances for utilizing crude G. trabeum cellulases and imply that the suboptimal hydrolysis levels obtained with G. trabeum and Celluclast 1.5 L cellulases, even at high loading levels, may be due to brown rot modifications insufficiently distributed throughout the pretreated material.
褐腐真菌通过创建被认为有助于通过不完全纤维素酶系选择性去除多糖的修饰来独特地降解木材。这种自然成功的机制为当前的生物加工应用提供了潜力。为了测试褐腐纤维素酶的功效，首先用褐腐菌 Gloeophyllum trabeum 降解南方黄松木块，时间分别为 0、2、4 和 6 周。对松木成分的表征揭示了褐腐腐烂模式，随着木质素组成的增加，选择性地去除了多糖。使用液体和固态 G. trabeum 纤维素酶提取物以及商业 Trichoderma reesei 提取物（Celluclast 1.5 L）对预处理材料进行糖化，使用β-葡萄糖苷酶修饰来消除纤维二糖到葡萄糖转化的限制。条件根据纤维素酶提取物的来源和浓度以及 pH 值（3.0 与 4.8）而变化。在 pH 值为 4.8 时，使用固态 G. trabeum 提取物可最大化水解产率。然而，葡萄糖释放的程度较低，当纤维素酶加载水平增加三倍时，也没有显著改变。此外，尽管 Celluclast 1.5 L 始终优于 G. trabeum 纤维素酶提取物，但葡萄糖释放的程度从未超过 22.0%。结果表明，利用粗 G. trabeum 纤维素酶的方法有所改进，并暗示即使在高加载水平下，G. trabeum 和 Celluclast 1.5 L 纤维素酶获得的水解水平不理想，可能是由于褐腐修饰物分布不均整个预处理材料。
