With the wide use of polyethylene film, the influence of polyethylene microplastic particles produced by its weathering on the rhizosphere soil microenvironment has attracted more and more attention from scientific research circles. In this study, the effects of low (0.2% w/w), medium (1% w/w), and high (2% w/w) doses of polyethylene particles and the combined reed biomass (2% w/w) on soil environmental factors and bacterial communities and metabolites in the reed rhizosphere were evaluated by a 90-day pot microscopic simulation system. The shape and surface microstructure of polyethylene particles in each treatment group changed obviously. A high (2% w/w) dose of microplastics significantly increased the TKN, TOC, and TP in reed root soil. The addition of the biomass significantly improved the activities of urease and sucrase in the soil. The α diversity of bacteria was not significantly affected by the addition of LDPE microplastics and biomass, but the β diversity of the bacterial community and the relative abundance of the Candidatus_Roku Bacteria, Chloroflexi, Unclassified_Blastocatella_Genus were significantly changed by the addition of middle (1% w/w) and high (2% w/w) doses of microplastics. In addition, the spectrum analysis of the soil metabolites showed that the abundance of soil metabolites was changed in each treatment group, and the differential metabolites were significantly up-regulated or down-regulated. Our findings provide a scientific reference to elucidate the impact of LDPE microplastic particles on the inter-rooted soil microenvironment and improve our understanding of the potential risks of microplastics in soil ecosystems.

In this study, we simultaneously investigated the community structure and abundance of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in the Grand Canal (the Zhenjiang section). Both clone library and qPCR (quantitative polymerase chain reaction) indicated that the abundance and diversity of AOB were higher than AOA in the Grand Canal for all four seasons. Among the 109 archaeal amoA sequences retrieved, 62.39 and 37.61% fell within the Nitrosopumilus and Nitrososphaera clusters, respectively. The 128 bacterial amoA gene sequences obtained in this study were grouped with known AOB sequences in the Nitrosomonas and Nitrosospira genera, which occupied 81.25 and 18.75% of the AOB group, respectively. The AOA abundance was significantly and positively correlated with the NH4-N. The AOB abundance did not show significant correlations with the measured parameters. Obvious differences were observed for the AOA community compositions obtained from different seasons. The community structure of AOB changed slightly. It indicated that AOB seemed to play a more important role for the nitrification process than AOA in this environment, and was more adapted to this environment.

—The microbial diversity and community structure of activated sludge in the biological treatment units of five municipal WWTPs and two industrial WWTPs were studied. The results showed that industrial WWTPs had the lowest diversity and abundance of activated sludge microbial communities, indicating that industrial wastewater inhibited the growth of microbial communities. In the correlation analysis between environmental factors and microbial diversity indices, pH and COD showed a significant negative correlation with the number of OTUs and microbial diversity. The main dominant microbial genus were Hyphomicrobium, Acinetobacter, Novosphingobium, Acinetobacter, and Meiothermus. Both principal coordinate analysis (PCoA) and phylogenetic analysis showed large differences in the structure of municipal and industrial microbial community structure, indicating the uniqueness of the activated sludge community structure in industrial WWTPs. Gene function predictions indicated that LJ had higher metabolic function associated with inorganic salt and lipid metabolism. Further co-occurrence network analysis showed that many of the key industrial WWTPs belonged in the same module, suggesting that they had strong interspecific interactions but were relatively independent from other microorganisms in the municipal WWTPs. This study broadens our understanding of microbial community differences between municipal WWTPs and industrial WWTPs.