消落带土壤黑碳降解过程中真菌群落结构及酶活特征

Fungal Community Structure and Ligninolytic Enzyme Activities during Decomposition of Soil Black Carbon in A Water-level-fluctuating Zone

黑碳是生物质或化石燃料不完全燃烧或岩石风化形成的一种富含芳香族基团的产物,普遍存在于环境中,在全球碳循环中占有重要的位置。早期黑碳被认为是不可降解的,近年来许多证据表明黑碳是可降解的。腐生真菌降解是其降解的重要途径,该过程需要木质素降解酶的参与。然而,目前对降解黑碳的真菌群落结构和酶的种类和活性认识十分有限。选取消落带的典型土壤为研究对象,采用18S r DNA基因测序法,解析了消落带土壤黑碳降解过程中真菌群落结构,测定了木质素降解酶活性。结果表明,(1)该区土壤真菌以子囊菌(Ascomycota)和担子菌(Basidiomycota)为主。其中子囊菌以粪壳菌纲(Sordariomycetes)为优势类群,其次为散囊菌纲(Eurotiomycetes)、座囊菌纲(Dothideomycetes);担子菌以伞菌纲(Agaricomycetes)为优势类群。(2)木质素过氧化物酶(Li P)、锰过氧化物酶(Mn P)和漆酶(Lac)在该区土壤中均有不同程度检出,与Li P和Lac相比,Mn P活性相对较低。同时明确了研究消落带土壤黑碳降解应从水分对降解过程的影响和机制入手,并重视环境效应。该研究可为深入研究黑碳的生物地球化学循环提供重要依据。

Black carbon （BC） is a general term used to describe products derived from incomplete combustion of vegetation and fossil fuels. BC may play an important role in the global C budget. Despite the relative recalcitrance of BC, recent laboratory and field studies indicated that BC can be degraded. Saprophytic fungi and ligninolytic enzyme may be important to soil BC degradation processes. Based on sequencing of the fungal 18S rDNA fragments and the measurements of soil enzyme activities, the main fungal populations and ligninolytic enzyme activities in the water-level-fluctuating zone of Danjiangkou were investigated. The results showed that the majority of the recovered sequences in the area belonged to diverse phylotypes of Ascomycota and Basidiomycota. Sordariomycetes, Eurotiomycetes and Dothideomycetes among Ascomycota was dominant, Agaricomycetes among Basidiomycota was dominant. Main ligninolytic enzyme had been detected in our study area. MnP activities are lower compared to LiP and Lac activities. The authors also propose the effects of water regimes on black carbon degradation process and mechanism require further investigations, further environmental effects could not be ignored. The study may be useful for BC biogeochemical cycles and will hopefully elicit more research in this field.