While municipal solid waste (MSW) provides an ideal habitat for pathogen propagation, the dynamics and assembly of airborne pathogen communities in these environments remain largely unknown. Here, we combined amplicon and metagenomics with spatiotemporal sampling to study inhalable particulate matter-carried potential pathogenic bacteria at full-scale food waste treatment plants (FWTPs), alongside comparisons to urban air in the area. The results showed that pathogenic bacteria constituted a notable portion (64.5 % ± 20.6 %, n = 75) of the total bacterial communities in FWTPs-impacted air, with species and relative abundance 2-4 times higher than that of urban air, and contributed over 50 % of pathogens to the outdoor air. Airborne pathogen community structures were highly shaped by sampling sites (i.e. treatment units), but conserved across seasons (summer vs. winter) and particle sizes (PM
Membrane biofouling is an unevadable problem that occurr during the reverse osmosis (RO) desalination of dyeing wastewater; therefore, it is necessary to minutely understand biofouling characteristics of RO membranes to effectively hinder the fouling.In this study, two sets of laboratory-scale desalination systems of biologically treated dyeing wastewater were operated, respectively, for 10 and 30 d, and the performance and biofouling of RO membrane were investigated.The obvious decrease of permeate flux after 10 d of operation reflected a more serious membrane fouling.The analysis on surface morphology, foulant characteristics, and active biomass of membrane fouling layer exemplified that biofouling was perhaps responsible for the permeate flux decline, and the fouling was more serious after operation of 30 d than that of 10 d.Further, bacterial community of biofilm showed that Proteobacteria was the most predominant, followed by Firmicutes and Bacteroidete.The relative abundance of γ-Proteobacteria significantly decreased and that of α-Proteobacteria, Clostridia, and Sphingobacteria increased with operation time, which seemed to facilitate the more developed/mature biofilm formation.The results would provide fundamental information for effective strategy on prevention and control of membrane biofouling during RO desalination of dyeing wastewater.
The dissemination and propagation of antibiotic resistance genes (ARGs) is an emerging global health concern, and the potential effects of nanomaterials on ARGs fates have drawn much attention recently. In the current study, the effects of metallic nanoparticles on ARGs occurrence of leachate culturable microbiota were investigated by four typical metal and metal oxide nanoparticles (Cu, Zn, CuO, and ZnO). The ARGs diversity was remarkably decreased during the cultivation and enrichment of leachate microbiota, and their abundances decreased for 1.4–3.2 orders of magnitude. The presence of nanoparticles facilitated the ARGs attenuation, and the magnitude of effects depended on types of nanoparticles and ARGs. Metal oxide nanoparticles caused more remarkable effects than metal nanoparticles. Mechanism analysis indicated that bacterial growth was inhibited, and the dissolved metal ions from nanoparticles partially contributed to nanoparticles decreasing ARGs. Flow cytometry experiments further confirmed that nanoparticles could enter bacterial cells, and then induce excessive reactive oxygen species (ROS) generation and increase membrane permeability. Finally, the possible mechanisms were put forward, and the structural equation models (SEM) differentiated the contribution of different factors shaping ARGs. The dissolved metal ions and growth inhibition caused by nanoparticles decreased ARGs transfer frequencies via exerting excessive metal stress and lowering population density. On the other hand, nanoparticles were incorporated into the cells, and then induced the generation of ROS, which might facilitate ARGs horizontal transfer via increasing membrane permeability, or decrease ARGs via the damage of genomic and plasmid DNA. Therefore, nanoparticles could affect ARGs fates via several ways, and combined effects finally determined the ARGs variations.
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