Department of Bioproducts and Biosystems Engineering, University of Minnesota, 2004 Folwell Avenue, Saint Paul, MN, 55108, USA.
Appl Microbiol Biotechnol. 2013 Oct;97(19):8831-40. doi: 10.1007/s00253-013-5142-0. Epub 2013 Aug 6.
Interest in the mechanisms of wood-degrading fungi has grown in tandem with lignocellulose bioconversion efforts, yet many potential biomass feedstocks are non-woody. Using corn stover (Zea mays) as a substrate, we tracked degradative capacities among brown rot fungi from the Antrodia clade, including Postia placenta, the first brown rot fungus to have its genome sequenced. Decay dynamics were compared against Gloeophyllum trabeum from the Gloeophyllum clade. Weight loss induced by P. placenta (6.2 %) and five other Antrodia clade isolates (average 7.4 %) on corn stalk after 12 weeks demonstrated inefficiency among these fungi, relative to decay induced by G. trabeum (44.4 %). Using aspen (Populus sp.) as a woody substrate resulted in, on average, a fourfold increase in weight loss induced by Antrodia clade fungi, while G. trabeum results matched those on stover. The sequence and trajectories of chemical constituent losses differed as a function of substrate but not fungal clade. Instead, chemical data suggest that characters unique to stover limit decay by the Antrodia clade, rather than disparities in growth rate or extractives toxicity. High p-coumaryl lignin content, lacking the methoxy groups characteristically cleaved during brown rot, is among potential rate-distinguishing characters in grasses. This ineptitude among Antrodia clade fungi on grasses was supported by meta-analysis of other unrelated studies using grass substrates. Concerning application, results expose a problem if adopting the strategy of the model decay fungus P. placenta to treat corn stover, a widely available plant feedstock. Overall, the results insinuate phylogenetically distinct modes of brown rot and demonstrate the benefit of using non-woody substrates to probe wood degradation mechanisms.
对木质素降解真菌机制的兴趣与木质纤维素生物转化工作同步增长，然而许多潜在的生物质原料是非木质的。以玉米秸秆（Zea mays）为底物，我们跟踪了来自 Antrodia 类群的褐腐真菌的降解能力，包括 Postia placenta，它是第一个基因组测序的褐腐真菌。将其与来自 Gloeophyllum 类群的 Gloeophyllum trabeum 进行了比较。在 12 周后，P. placenta（6.2%）和其他五个 Antrodia 类群分离株（平均 7.4%）在玉米秸秆上引起的失重表明，与 G. trabeum（44.4%）引起的腐烂相比，这些真菌的效率较低。使用白杨（Populus sp.）作为木质底物，导致 Antrodia 类群真菌引起的失重平均增加了四倍，而 G. trabeum 的结果与秸秆的结果相匹配。化学组成损失的序列和轨迹因底物而异，但与真菌类群无关。相反，化学数据表明，秸秆特有的特征限制了 Antrodia 类群的腐烂，而不是生长速度或提取物毒性的差异。缺乏在褐腐过程中典型裂解的甲氧基的高对香豆素木质素含量是禾本科植物中潜在的速率区分特征之一。在禾本科植物上，Antrodia 类群真菌的这种无能得到了使用禾本科植物作为底物的其他不相关研究的荟萃分析的支持。在应用方面，如果采用模型褐腐真菌 P. placenta 来处理玉米秸秆（一种广泛可用的植物饲料），那么结果就会暴露一个问题。总的来说，这些结果暗示了褐腐的系统发育上不同的模式，并证明了使用非木质底物来探究木材降解机制的好处。
