Microbial community structure and diversity in a municipal solid waste landfill

Municipal solid waste (MSW) landfills are the most prevalent waste disposal method and constitute one of the largest sources of anthropogenic methane emissions in the world. Microbial activities in disposed waste play a crucial role in greenhouse gas emissions; however, only a few studies have examined metagenomic microbial profiles in landfills. Here, the MiSeq high-throughput sequencing method was applied for the first time to examine microbial diversity of the cover soil and stored waste located at different depths (0-150 cm) in a typical MSW landfill in Yangzhou City, East China. The abundance of microorganisms in the cover soil (0-30 cm) was the lowest among all samples, whereas that in stored waste decreased from the top to the middle layer (30-90 cm) and then increased from the middle to the bottom layer (90-150 cm). In total, 14 phyla and 18 genera were found in the landfill. A microbial diversity analysis showed that Firmicutes, Proteobacteria, and Bacteroidetes were the dominant phyla, whereas Halanaerobium, Methylohalobius, Syntrophomonas, Fastidiosipila, and Spirochaeta were the dominant genera. Methylohalobius (methanotrophs) was more abundant in the cover layers of soil than in stored waste, whereas Syntrophomonas and Fastidiosipila, which affect methane production, were more abundant in the middle to bottom layers (90-150 cm) in stored waste. A canonical correlation analysis showed that microbial diversity in the landfill was most strongly correlated with the conductivity, organic matter, and moisture content of the stored waste.