贵州典型煤矸石堆场微生物群落结构及功能特征

Structural and functional characteristics of microbial communities of typical coal gangue dumps in Guizhou Province

摘要:

【背景】煤矸石堆场用于堆放煤矿开采过程中产生的一种热值低、含重金属的固体废弃物，会产生大量的酸性废水，对堆场周边的生态环境造成严重影响。【目的】探究煤矸石堆场的微生物群落结构和功能特征。【方法】选择贵州省六枝特区典型煤矸石堆场作为研究对象，采集堆场表层土壤、矸石层土壤、废水浸出口沉积物和堆场下游河道沉积物，通过宏基因组学技术进行分析。【结果】细菌的优势菌门为变形菌门(Proteobacteria)和放线菌门(Actinobacteria)，优势菌属为钩端螺菌属(Leptospirillum)和硫化杆菌属(Sulfobacillus)；古菌的优势菌门为Candidatus_Thermoplasmatota和泉古菌门(Crenarchaeota)，优势菌属为热原体属(Thermoplasma)和金属球菌属(Metallosphaera)。不同采样点细菌和古菌的优势菌属存在显著差异，矸石层土壤和废水浸出口沉积物中的铁氧化细菌和硫氧化细菌比其他2个样点丰富。煤矸石堆场中微生物的碳、氮、硫代谢基因丰度较高，共检测到6条固碳途径、6条氮代谢途径和3条硫代谢途径。主要的固碳基因为ACAT和E2.2.1.1，固碳途径以还原性三羧酸循环为主；主要的氮代谢基因为nirB、nasA和narG，氮代谢途径以反硝化为主；主要的硫代谢基因为cysH和sir，硫代谢途径以同化硫酸盐还原为主。【结论】本研究可进一步拓展对矿山生态环境的认识，为矿区生态修复、土壤和河流污染的治理提供理论依据。

关键词:煤矸石堆场;宏基因组学;微生物群落;代谢途径;功能基因

Abstract:

[Background] Coal gangue dumps stockpile coal wastes with low calorific values and heavy metals, which are generated during coal mining, along with a large amount of acidic wastewater and deteriorated eco-environment nearby. [Objective] This paper aims to explore the structure and functional characteristics of microbial communities in coal gangue dumps. [Methods] The soil samples of the dump surface and gangue layers, as well as the sediment samples from wastewater leaching outlets and dump downstream river, of a typical gangue dump in Liuzhi special district, Guizhou Province were collected. Metagenomics was employed to reveal the microbial community structures and functional characteristics of the samples. [Results] The results showed that bacteria were more diverse and abundant than archaea. The dominant bacterial phyla were Proteobacteria and Actinobacteria, and the dominant genera were Leptospirillum and Sulfobacillus. The dominant archaeal phyla were Candidatus_ Thermoplasmatota and Crenarchaeota, and the dominant genera were Thermoplasma and Metallosphaera. The dominant genera of bacteria and archaea in different sampling sites varied from each other, and Fe-oxidizing bacteria (FOB) and sulfur-oxidizing bacteria (SOB) were more abundant in the gangue layer soil and wastewater leaching outlet sediment than in the other two sampling sites. The genes for carbon, nitrogen, and sulfur metabolism were abundant in coal gangue, with six carbon fixation pathways, six nitrogen metabolism pathways, and three sulfur metabolism pathways detected. The dominant genes for carbon fixation were ACAT and E2.2.1.1, and the dominant pathway was reductive tricarboxylate cycle. For nitrogen metabolism, the dominant genes were nirB, nasA and narG, and the dominant pathway was denitrification. For sulphur metabolism, the dominant genes were cysH and sir, and the dominant pathway was assimilated sulphate reduction. [Conclusion] The findings are expected to enhance the understanding of mine ecology and provide a theoretical basis for the ecological restoration and pollution treatment in mining areas.

Key words:coal gangue dumps;metagenomics;microbial communities;metabolic pathways;functional genes