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【目的】微生物土壤结皮(Microbial soil crusts,MSCs)对于遏制土壤荒漠化、恢复荒漠地区生态环境起着重要作用。MSCs中的微生物,特别是纤维素降解菌,起着稳固、修复生态环境的功能。外源纤维素诱导是全面认识MSCs中纤维素降解细菌的多样性及其在MSCs形成和发展中的作用的重要途径【。方法】通过对微生物土壤结皮分别添加小麦秸杆(麦秸)、锯末木屑两类纤维素材料进行诱导,以PCR-DGGE方法分析细菌群落变化。【结果】外源纤维素,特别是麦秸的添加会迅速提高MSCs中细菌丰富度及多样性,将细菌丰富度提高约66.7%,Shannon-Weiner指数提高约15.8%;相同处理的样品聚类位置较近,说明纤维素对于MSCs细菌菌群变化起主导作用;细菌群落结构组成在添加纤维素诱导后发生了变化,麦秸诱导样品与同时期对照样品差异最大,但各样品中Firmieutes和Alphaproteobacteria始终为优势类群;所得DGGE条带序列中有13条与纤维素降解菌序列同源性相近,他们所代表的细菌很可能具有纤维素降解能力,其中厌氧性的梭菌属(Clostridium)所占比例最大,约为46.1%,其次为芽孢杆菌属(Bacillus),约占30%;纤维素降解过程中,诱导增加了MSCs发育有重要作用的一些类群如Microcoleus vaginatus和一些Alphaproteobacteria类群细菌等的丰度和多样性,它们中有的可通过分泌多糖物质等增强土壤颗粒黏结、有的可以其固碳或固氮等能力提高土壤营养水平。【结论】为认识外源纤维素诱导MSCs细菌群落结构的变化规律,MSCs中纤维素降解细菌的多样性及纤维素降解细菌对MSCs形成和发展的作用提供了基础,同时也为恢复荒漠生态系统实践方法提供了理论依据。
【Objective】 Microbial soil crusts (MSCs) play an important role in curbing soil desertification and restoring the ecological environment in desert regions. Microorganisms in MSCs, especially cellulose-degrading bacteria, play a solid role in the restoration of ecological environment. Exogenous cellulose induction is an important way to fully understand the diversity of cellulolytic bacteria in MSCs and their role in the formation and development of MSCs. Methods The soil microbial crusts were respectively treated with wheat straw (wheat straw) and sawdust chips, and the bacterial community was analyzed by PCR-DGGE. 【Result】 The results showed that the addition of exogenous cellulose, especially wheat straw, rapidly increased the bacterial abundance and diversity in MSCs, increased the bacterial abundance by 66.7% and the Shannon-Weiner index by 15.8% The results showed that the cellulose played a leading role in the changes of bacterial flora of MSCs. The bacterial community composition changed after the addition of cellulose, and the difference between the straw-induced and the control samples was the highest, but Firmieutes and Alphaproteobacteria in each sample were always Among the obtained DGGE bands, 13 were similar to those of cellulose-degrading bacteria. The bacteria they represent are likely to have cellulolytic activity. Among them, the proportion of anaerobic Clostridium The highest was about 46.1%, followed by Bacillus, accounting for about 30%. The abundance of some species such as Microcoleus vaginatus and some Alphaproteobacteria groups that induced the increase of MSCs’ development during cellulose degradation And diversity, some of which can enhance soil particle bonding by secreting polysaccharides and others, and some can increase their carbon sequestration or nitrogen fixation Soil nutrient levels. 【Conclusion】 In order to understand the changing rules of bacterial community structure of MSCs induced by exogenous cellulose, the diversity of cellulolytic bacteria in MSCs and the role of cellulolytic bacteria in the formation and development of MSCs, as well as to restore the desert ecosystem Practice provides a theoretical basis.