Different Responses of Soil Microbial Community Structure to Irrigation with Treated Wastewater from Domestic and Industrial Sources

Abstract

To investigate the long-term effects of irrigation with treated domestic and industrial wastewater on the microbial community structure of the soil, Illumina MiSeq high-throughput sequencing technology was applied. Groundwater irrigated soil was used as a control. The effects of soil environmental factors and their interactions on the microbial community structure were investigated. Compared with the groundwater irrigation, irrigation with treated domestic wastewater can significantly increase the contents of TOC, DOC, Eh, NH4+-N, and TP, whereas irrigation with treated industrial wastewater can increase the contents of Cd, Cr, Cu, Pb, and Zn in the soil. Irrigation with treated wastewater also increases the relative abundance of Acidobacteria and Planctomycetes, and reduces the relative abundance of Firmicutes and Tectomicrobia. The effects of treated wastewater from different sources on functional microorganisms in soil are also different; irrigation with treated domestic wastewater can increase the relative abundance of Chloroflexi and Nitrospirae, whereas irrigation with treated industrial wastewater has negative effects on the abundance of Actinobacteria. The results of db-RDA analysis show that TN, TP, DOC, and Eh are the main factors that impact the microbial communities in soils irrigated with treated domestic wastewater (P<0.05), and heavy metals are the main factors that impact the microbial communities in soils irrigated with treated industrial wastewater (P<0.05). Compared with groundwater irrigation, treated wastewater irrigation can change the correlations between soil environmental factors, which in turn affect the microbial community structure. The growth of microorganisms in soils irrigated with treated domestic wastewater is mainly controlled by the increase in the nutrients such as DOC, TN, and TP and changes in soil redox conditions. The abundance of microorganisms in soil irrigated with treated industrial wastewater is significantly correlated with the accumulation of heavy metals.