Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount Avenue, Montréal, Quebec, Canada.
ISME J. 2010 Sep;4(9):1206-14. doi: 10.1038/ismej.2010.41. Epub 2010 Apr 15.
The fate of the carbon stocked in permafrost following global warming and permafrost thaw is of major concern in view of the potential for increased CH(4) and CO(2) emissions from these soils. Complex carbon compound degradation and greenhouse gas emissions are due to soil microbial communities, but no comprehensive study has yet addressed their composition and functional potential in permafrost. Here, a 2-m deep permafrost sample and its overlying active layer soil were subjected to metagenomic sequencing, quantitative PCR (qPCR) and microarray analyses. The active layer soil and the 2-m permafrost microbial community structures were very similar, with Actinobacteria being the dominant phylum. The two samples also possessed a highly similar spectrum of functional genes, especially when compared with other already published metagenomes. Key genes related to methane generation, methane oxidation and organic matter degradation were highly diverse for both samples in the metagenomic libraries and some (for example, pmoA) showed relatively high abundance in qPCR assays. Genes related to nitrogen fixation and ammonia oxidation, which could have important roles following climatic change in these nitrogen-limited environments, showed low diversity but high abundance. The 2-m permafrost showed lower abundance and diversity for all the assessed genes and taxa. Experimental biases were also evaluated using qPCR and showed that the whole-community genome amplification technique used caused representational biases in the metagenomic libraries by increasing the abundance of Bacteroidetes and decreasing the abundance of Actinobacteria. This study describes for the first time the detailed functional potential of permafrost-affected soils.
考虑到这些土壤中 CH(4) 和 CO(2) 排放增加的可能性，全球变暖及多年冻土解冻后多年冻土中储存的碳的命运是主要关注点。复杂的碳化合物降解和温室气体排放是由土壤微生物群落引起的，但迄今为止，还没有综合研究解决其在多年冻土中的组成和功能潜力。在这里，对 2 米深的多年冻土样本及其上层活动层土壤进行了宏基因组测序、定量 PCR（qPCR）和微阵列分析。活动层土壤和 2 米深多年冻土微生物群落结构非常相似，优势门为放线菌。这两个样本的功能基因谱也非常相似，尤其是与其他已发表的宏基因组相比。在宏基因组文库中，与甲烷生成、甲烷氧化和有机质降解相关的关键基因高度多样，一些基因（例如 pmoA）在 qPCR 分析中显示出相对较高的丰度。与固氮和氨氧化有关的基因，在这些氮限制环境中气候变化后可能具有重要作用，其多样性较低但丰度较高。所有评估的基因和分类单元在 2 米深的多年冻土中的丰度和多样性均较低。还使用 qPCR 评估了实验偏差，结果表明，全社区基因组扩增技术通过增加拟杆菌门的丰度和降低放线菌门的丰度，在宏基因组文库中引起了代表性偏差。本研究首次描述了受多年冻土影响的土壤的详细功能潜力。
