Response of bacterial communities in coastal mudflat saline soil to sewage sludge amendment

Microbial communities are of great importance in the development of saline soil fertility in coastal mudflats. However, the effects of sewage sludge use on the microbiome in saline soils of mudflats are unknown. This study aimed to investigate the response profile of bacterial communities in mudflat saline soil to sewage sludge amendment (SSA). Mudflat soil was treated once at the rates of 0, 30, 75, and 150 ton sewage sludge per hectare. Ryegrass, Sesbania, and Maize were successively planted and tilled. Approximately 3 years after the initial amendment, the Illumina Miseq sequencing of the 16S rRNA gene was performed to study bacterial community of mudflat soil. The results indicated that SSA significantly changed the mudflat saline soil bacterial community. A total of 37 phyla were found, dominated by Bacteroidetes, Proteobacteria, Chloroflexi, Actinobacteria, Acidobacteria, Planctomycetes, and Firmicutes. The SSA resulted in an increase in the comparable richness of Chloroflexi, Planctomycetes and Firmicutes, as well as a decrease in Proteobacteria. The canonical correspondence analysis indicated that the bacterial community structure was negatively affected by alkalinity or salinity, while positively affected by soil organic matter, and the N and P concentration in the saline soil. The bacterial community composition in the saline soil was altered by SSA. Lower salinity and alkalinity, and higher organic matter and nutrients favored microhabitats more suitable for bacteria.