玉米秸秆厌氧降解微生物群落结构解析及调控研究
文献类型：学位论文
| 作者 | 乔江涛 |
| 学位类别 | 硕士 |
| 答辩日期 | 2013-07 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 邱艳玲 |
| 关键词 | 玉米秸秆 厌氧降解 群落结构 16S rRNA 基因克隆文库 代谢调控 |
| 学位专业 | 生物化学与分子生物学 |
| 中文摘要 | 秸秆沼气技术不仅能够提供清洁能源，又可以充分利用农业废弃物，保护和改善生态环境。由于秸秆的木质纤维素含量高、结构复杂，同时表面还包裹一层蜡质层，导致秸秆生物自然降解极其缓慢，以秸秆为主要原料的沼气发酵仍存在许多技术难题。秸秆降解微生物研究对于深入理解秸秆厌氧消化本质、提高秸秆厌氧降解率及产气量具有重要意义。国外主要以青贮秸秆作为混合发酵原料，没有以干秸秆作为单一物料的沼气工程，相关微生物信息未见报道。本研究为了掌握参与秸秆厌氧降解的优势微生物菌群，以自然界秸秆堆积土壤、水淹稻田、腐烂稻草等木质纤维素降解样品为接种物，以玉米秸秆为唯一碳源，进行了秸秆厌氧降解微生物的驯化培养，构建了8组复合菌系。结合复合菌系的产甲烷特性，有机酸、pH等理化指标及微生物群落结构研究，发现水解发酵性细菌是秸秆厌氧降解的优势菌群，并且微生物群落结构与发酵pH存在映衬关系：甲烷产量高的复合菌系，pH中性，微生物多样性较高；而甲烷产量低的复合菌系，pH偏酸性，微生物多样性较低，厚壁菌门（Firmicutes）和拟杆菌门（Bacteroidetes）微生物占绝对优势。为了进一步掌握实际秸秆沼气工程的微生物群落结构，以运行稳定的秸秆沼气工程沼液为研究对象进行了研究。沼液产甲烷活性实验表明，沼液对玉米秸秆具有较高的总固体（TS）去除率及甲烷产率，说明以玉米秸秆为原料进行沼气发酵具有很大的应用潜力。在秸秆降解过程中，除有机酸外，还检测到对甲酚、苯丙酸、苯酚等芳香族化合物，说明木质素可能参与了厌氧降解。克隆文库解析表明秸秆实际沼气工程的微生物多样性更高，群落结构更复杂，水解发酵性细菌占绝对优势。在掌握秸秆厌氧降解优势功能菌群的基础上，为提高秸秆沼气发酵的甲烷产量，考察了添加各阶段（水解发酵、产氢产乙酸及产甲烷）功能菌群对秸秆甲烷产率的影响，发现添加共生菌群、氢营养型产甲烷菌及乙酸型产甲烷菌的强化效果最佳，甲烷产量提高30%左右，初步确立了秸秆沼气发酵生物强化的最佳接种量为10%。 |
| 英文摘要 | Straw biogas technology can not only produces clean energy, but also make full use of agricultural residues and provide a basis for environmental protection and sustainable development. Because of high amounts of cellulose, hemicellulose, and lignin and its wax layer structure, which makes crop straw decomposition process very slowly and technical problems still existed. The research on anaerobic corn straw degrading microbial community is of significance to understand the essential of corn straw degradation and improve the degradation rate and gas production. The general pattern of corn straw biogas reactor was co-digestion of silage corn straw with other wastes, hoverer, there is no full-scale biogas reactor used the corn straw as the sole feedstock. In addition, the knowledge of the microbial community involved in anaerobic digestion system for the treatment of crop residues is still limited.To get a grasp of the microbial communities in anaerobic corn straw degrading microbial systems, methanogenic corn stalk degrading enrichment cultures were constructed using corn stalk as the sole carbon source and eight types of environmental samples such as rice, corn, wheat soils and reed swamp as inocula. Combined methane production, volatile acids, pH and microbial communities, we found fermentative heterotrophs were the major bacterial community and microbial community structure and fermentation pH has a corresponding relationship: bacterial diversity was higher in cultures with neutral pH than those with acidic pH. Overall, clones affiliated with the phylum Firmicutes and Bacteroidetes were the most frequently and commonly observed in cultures with acidic pH. To get deep insights into microbial communities involved in full-scale reactor treating corn straw, anaerobic biogas slurry was taken from a full-scale mesophilic (35°C), anaerobic completely stirred tank reactor (CSTR) (volume, 500 liters) constructed in China. Corn straw biogas slurry showed high specific methane yield and TS removal rate, suggesting crop residues are promising alternative feedstocks for biogas production. During anaerobic degradation of corn straw, volatile acids and aromatic compounds (p-cresol, phenylpropionate, phenol and benzoate) were detected as transient intermediates, indicating lignin could decomposed under anaerobic condition. Phylogenetic analysis indicated biogas slurry showed higher microbial diversity and more complex community structure. Fermentative heterotrophs were the predominant bacterial community. On basis of knowledge on dominant functional microbial groups, the biotechnological intensification of biogas production was studied by adding various microbes to hydrolytic and fermentative, acetogenic and methanogenic stages of straw degradation, respectively. The results showed that methane increased 30% upon addition of syntrophic bacterial groups, hydrogenotrophic methanogens and aceticlastic methanogens, and the optimum inoculum size (10%) was estibalished for corn straw degrading microbial system. |
| 学科主题 | 生物制氢与沼气 |
| 公开日期 | 2013-07-13 |
| 源URL | [http://ir.qibebt.ac.cn:8080/handle/337004/1516]  |
| 专题 | 青岛生物能源与过程研究所_生物制氢与沼气团队 |
| 推荐引用方式 GB/T 7714 | 乔江涛. 玉米秸秆厌氧降解微生物群落结构解析及调控研究[D]. 北京. 中国科学院研究生院. 2013. |
入库方式： OAI收割
来源：青岛生物能源与过程研究所
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