基于宏基因组的青海农用沼气池微生物组成和功能分析

Metagenomic Analysis of Microbial Community Composition and Function in Rural Household Biogas Digesters in Qinghai Province

以产气性能不同的青海农用沼气池为研究对象,利用宏基因组技术分析了全年温度最高和最低时期污泥样品的微生物组成和功能特征。物种注释显示发酵系统中蕴藏着丰富的微生物种群。在细菌类群中,拟杆菌门、厚壁菌门和变形菌门丰度最高,占所有菌群相对丰度的72.37%~74.00%,参与关键的发酵作用。在4种样品中,互养菌门(相对丰度1.62%~4.73%)丰度偏低,与沼气产气的变化规律相一致,可能是沼气生产重要的功能类群。在属水平上,优势类群依次是海螺菌属(相对丰度6.75%)、梭菌属(相对丰度4.56%)、密螺旋体属(相对丰度3.60%)和假单胞菌属(相对丰度3.01%)。古菌类群中,产甲烷菌属(相对丰度25.41%~31.65%)是最优势类群,也是最主要的产气功能类群。功能注释表明,产气好比产气差的样品具有更多的有效基因,参与甲烷代谢相关路径的功能基因丰度更高。在样品中,甲烷代谢途径涉及的氢代谢营养型产甲烷菌参与CO2还原反应,所有代谢通路完整,且产气好的样品功能酶基因丰度趋高。研究结果表明,在青海农用沼气发酵系统中,甲烷产生的途径主要依赖于H2氧化/CO2还原的合成。

Taking the rural household biogas digesters with desirable and undesirable biogas productivity in Qinghai Province as study objects,the metagenomics methods were applied to investigate the microbial community structure and the functional characteristics in the sludge samples of digesters at annual peak and nadir temperatures.Species annotation results indicated high taxon richness and biodiversity in the fermentation system.Concerning bacterial groups,Bacteroidetes,Firmicutes and Proteobacteria were the most abundant species,accounting for 72.37%~74.00%relative abundance of all floras,and they might play key roles in the fermentation.The abundance of Synergistetes(1.62%~4.73%relative abundance)in each sample was consistent with the varied biogas productivity,so the Synergistetes could be an important functional group considerably affecting biogas production.At genus level,Marinospirillum(6.75%),Clostridium(4.56%),Treponema(3.60%),and Pseudomonas(3.01%)were the dominant groups.Regarding archaeal groups,Methanogenium(25.41%~31.65%relative abundance)was the most dominant and decisive function-group for biogas production.Functional annotations indicated that samples from digesters with higher biogas production had more effective genes than the digesters with lower biogas production,and that the functional genes involved in methane metabolism pathways showed significantly higher abundance.The methane metabolic pathways to reduce CO2 by hydrogenotrophic methanogens were complete in all samples,and the abundance of functional enzyme genes was higher in the samples with higher biogas production.The research result indicated that H2-oxidating/CO2-reducing was the major pathway for methane production in the Qinghai biogas rural fermentation system.