Study of bacterial community structure characteristics in humus soils of different landfill ages

In order to explore the effect of landfill time on the bacterial community structure of humus soil, taking humus in a domestic waste landfill in Jiangsu Province, China as the research object, Illumina Miseq high-throughput sequencing technology was used to analyze the bacterial community composition of humus and the surrounding soil with landfill time of 1-3 years, 3-6 years and 6-10 years. The results showed that the richness and diversity of the bacterial community in humus soil increased with the landfill time, but they were lower than those in the surrounding soil. Non metric multidimensional scaling (NMDS) analysis showed that the bacterial community structure difference was bigger in humus soil of different landfill time, but the similarity between the bacterial community in the soil surrounding the landfill site and the humus soil buried for 6-10 years was relatively high, which may be caused by the surrounding soil being polluted by landfill leachate to some extent. Firmicutes, Proteobacteria, Actinobacteriota, Chloroflexi and Bacteroidota were the dominant phylum in humus soil at each stage. The relative abundance of Firmicutes increased first and then decreased with the landfill time, the change of Chloroflexi was the opposite. The relative abundance of Bacteroidetes decreased at the later stage of landfill, while the relative abundance of Proteobacteria and Actinobacteria did not change significantly during the whole process. Redundant analysis (RDA) results showed that the change of bacterial community structure in humus soil was closely related to total nitrogen (TN), heavy metals (Cd, Zn) and pH.