复配菌群降解煤产甲烷的宏基因组与宏转录组分析

Metagenomic and Metatranscriptomic Analysis of Methanogenesis from Coal Degradation by Compounded Microflora

【目的】芳香化合物代谢是微生物降解煤产甲烷的限制因素。为了提高煤的生物甲烷产量,经过富集、驯化获得煤降解产甲烷菌群(RI)和菲降解功能菌群,并通过二者配伍获得复配菌群(CM)。【方法】采用宏基因组与宏转录组相结合方法分析CM与RI的菌群结构及代谢途径的异同。【结果】复配后菌群的甲烷产量明显提高,增产114.55%。复配显著提高了芳香化合物降解菌的占比,如Pseudomonas的占比高达63.49%;同时提高了优势菌的代谢活性以及芳香化合物代谢途径中各关键酶的合成和表达。CM中芳香族化合物降解途径的基因丰度是RI的1.65倍,基因表达丰度是RI的6.34倍(P<0.05)。其中,关键酶EC:1.13.11.2基因丰度和表达丰度分别是RI的2.24、62倍。这些酶表达丰度的增加促使更多的芳香族化合物代谢为丙酮酸。复配同时增强了丙酮酸代谢为乙酰辅酶A过程的基因表达,该代谢途径中关键酶EC:1.2.4.1的表达丰度在CM中可达到RI的14.70倍。CM中各产甲烷途径的基因表达丰度也高于RI,是RI的2.66-7.10倍。【结论】复配富集了芳香化合物降解菌,并显著提高了芳香化合物降解产甲烷整个代谢途径中基因丰度,尤其是基因表达丰度,从而提高甲烷产量。

【Objective】Aromatic compound metabolism is considered a limiting factor for the generation of biogenic coalbed methane.To increase biomethane production from coal,the compounded microflora(CM)was obtained by compounding raw inoculum(RI)with ability of producing methane by degrading coal and phenanthrene-degrading functional microflora enriched from produced water.【Method】A combined metagenome and metatranscriptome approach was used to analyze the differences in the community structure and metabolic pathways of CM and RI.【Result】The methane yield of CM increased significantly by 114.55%.Compounding significantly increased the proportion of aromatics-degrading bacteria,such as Pseudomonas,accounting for 63.49%,and also increased the metabolic activity of the dominant bacteria as well as the synthesis and expression of the key enzymes in the metabolic pathway of aromatic compounds.Gene abundance of the aromaticsdegrading pathway in CM was 1.65 times higher than that of RI,and the gene expression abundance was 6.34 times higher than that of RI(P<0.05).The gene abundance and expression abundance of EC:1.13.11.2 were 2.24 and 62 times higher than those of RI,respectively.The increased expression abundance of these enzymes prompted the transformation of aromatic compounds to pyruvate.Compounding also enhanced the gene expression during the process of pyruvate metabolism to acetyl-CoA.The expression abundance of EC:1.2.4.1 reached 14.70-fold of the RI in CM.The gene expression abundance of the respective methanogenic pathways in CM was 2.66 to 7.10-fold of the RI.【Conclusion】The compounding enriched the aromatics-degrading bacteria and significantly increased gene abundance,especially gene expression abundance,in the whole metabolic pathway of degrading aromatics to methane generation,resulting in the increased methane production.