The initial adhesion of microbes onto plastics is crucial for the subsequent formation of the plastisphere, which might be affected by signal molecules commonly present in bacteria-related environments that regulate cell-to-cell communication. Herein, the initial retention performance of E. coli onto six types of plastics, both without and with N-acyl-homoserine lactones (AHLs, a common signal molecule) at concentrations ranging from 10 ng/L to 100 μg/L in suspension, was determined to reveal the influence of signal molecules on the formation of the plastisphere. We found that AHLs coexisting in suspensions significantly enhanced bacterial adhesion performance onto plastics, regardless of plastic types and AHL types, with a more pronounced enhancement observed at higher AHL concentrations. This enhanced bacterial adhesion induced by AHLs also held true in solutions containing humic acid, in river water, and in sewage. AHLs stimulated the synthesis of EPS, enhanced EPS hydrophobicity by altering the protein/polysaccharide ratio and its secondary structures, and upregulated pathways related to flagellar assembly, quorum sensing, protein production, and biofilm formation, thereby enhancing bacterial adhesion capability onto plastics. Moreover, AHLs adsorbed onto plastic surfaces could induce chemoattraction effects, further promoting bacterial adhesion performance. Obviously, through various mechanisms, the signal molecules greatly influence the initial adhesion of bacteria onto plastics in aquatic systems.

Antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in aquatic environments pose threats to ecosystem safety and human health, which could not be efficiently removed by conventional disinfection techniques. Herein, layered FeOCl with coordinatively unsaturated Fe sites were fabricated and used to activate Fe(VI) for the efficient ARB/ARG removal in the present study. We found that highly reactive Fe(IV)/Fe(V) intermediates were generated in the FeOCl/Fe(VI) system, rapidly disinfecting 1 × 107 CFU mL–1 ARB to below the limit of detection within only 6 min. Via the combination of in situ characterization and theoretical calculations, we revealed that Fe(VI) was preferentially adsorbed onto Fe sites on the (010) plane of FeOCl and subsequently activated to produce reactive Fe(IV)/Fe(V) through direct electron transfer. Meanwhile, O2•– generated from O2 activation on the FeOCl surface enhanced Fe(VI) conversion to Fe(IV)/Fe(V). During the disinfection process, intracellular/extracellular ARGs and DNA bases were simultaneously degraded, inhibiting the potential horizontal gene transfer process. The FeOCl/Fe(VI) system could effectively disinfect ARB under complex water matrices and in real water samples including tap water, lake water, and groundwater. When integrated into a continuous-flow reactor, the FeOCl/Fe(VI) system with excellent stability successively disinfected ARB. Overall, the FeOCl/Fe(VI) system showed great promise for eliminating ARB/ARGs from water.

Injection of bacteria with petroleum degrading capability into contaminated sites is one of the most cost-effective and environmental friendly strategies for the successful remediation of petroleum-contaminated groundwater. The successful in-situ bioremediation of petroleum contamination in subsurface is greatly impacted by the mobile/retention performance of petroleum-degrading bacteria in porous media, which yet is not well understood. The present study systematically investigated the mobile performance of petroleum-degrading strains in porous media with petroleum contamination under environmentally relevant solution and flow conditions. We found that although the mobile performance of petroleum-degrading bacteria was similar to petroleum non-degrading bacteria in uncontaminated porous media, bacteria containing different petroleum degrading function yet exhibited opposite transport behaviors in petroleum contaminated porous media. Enhanced mobility in porous media with petroleum contamination was achieved for petroleum non-degrading bacteria, while reduced mobility was obtained for petroleum-degrading bacteria. Combining the batch adsorption experiments, capillary chemotaxis assays, in-situ microfluidic chamber experiments together with theoretical calculation, we found that the opposite mobile performance observed for bacteria containing different petroleum degrading functions could be mainly attributed to their different chemotactic responses towards petroleum with negative and positive chemotaxis response respectively for non- and petroleum-degrading bacteria. Clearly, pollutant-degrading bacteria exhibited different mobile performance from non-degrading bacteria in contaminated porous media. The previous findings achieved from the model bacteria without pollutant-degrading capability could not be simply used to predict the mobile performance of pollutant-degrading bacteria. To ensure the successful implementation of in-situ bioremediation, the mobility of pollutant-degrading bacteria in contaminated porous media should be fully understood.

Current antibiotic-resistant bacteria (ARB) disinfection techniques commonly rely on large dosages of oxidants, resulting in the presence of considerable amounts of residuals and toxic disinfection byproducts (DBPs) in water. Herein, we propose a highly effective ARB disinfection approach via activating an ultralow concentration (10 μM) of chlorite (ClO2–) by naturally abundant sunlight to generate various reactive species (i.e., HO•, Cl•, ClO•, and ClO2) with negligible generation of halogenated DBPs. Combining in situ characterization with theoretical calculations, we reveal that, in addition to the photolysis of ClO2– in the bulk solution, ClO2– ions electrostatically adsorbed on the positive local sites of lipids can boost light absorption and facilitate the in situ generation of reactive species upon sunlight irradiation, enabling more efficient attacks toward cell membranes and the intracellular antioxidant enzyme system. The intracellular antibiotic resistance genes (ARGs) are then released and further degraded, inhibiting horizontal ARG transfer. This approach can also achieve excellent ARB disinfection performance in real water matrices (e.g., lake and river water) in 1 L tanks and 500 mL plastic bottles with natural sunlight irradiation. Overall, this work presents an efficient, safe, and sustainable method to inactivate ARB with deep insights into disinfection mechanisms at the subcellular level.

Insufficient charge separation and sluggish two-electron water-oxidation reaction are two critical factors restricting the photosynthesis performance of metal-free covalent organic frameworks (COFs) for hydrogen peroxide (H2O2) generation from naturally abundant water and air. Herein, we develop a facile strategy to simultaneously boost the charge-separation efficiency and water-oxidation capability through constructing short and rapid charge-transfer tunnels within highly charge-confined COFs via replacing the phenyl with pyrimidine. Compared with a single charge-transfer tunnel within a lowly charge-confined COF-5-(4-aminophenyl)pyrimidin-2-amine (APM) with pyrimidine, dual charge-transfer tunnels are constructed within a highly charge-confined COF-5,5′-bipyrimidine-2,2′-diamine (BPM) with bipyrimidine due to the ground-state charge transfer between para-carbon and meta-nitrogen, which significantly accelerates the intermolecular charge-transfer process and prevents charge recombination. This strategy also decreases the energy barrier of rate-determining water oxidation in H2O2 photosynthesis and thus promotes the effective generation of the key *OH intermediates, facilitating the generation of H2O2 at a production rate of 5521 μmol g−1 h−1 from water, oxygen and light without sacrificial reagents or additional energy consumption by COF-BPM. Furthermore, COF-BPM can also efficiently produce H2O2 under broad pH conditions, in widely available real water, on a floatable foam sheet, in a continuous-flow reactor and in a scaled-up reactor by using natural solar light for water decontamination.

Sunlight-driven photosynthesis by covalent organic frameworks (COFs) from water and air without using sacrificial reagents is a promising H2O2 fabrication approach, but is still restricted by the insufficient charge separation and sluggish 2e- water oxidation process. Herein, we provide a facile strategy to simultaneously improve charge separation and water oxidation in COFs via confining the charge transfer pathways from two diversion ones to a confluence one through regulating the site of nitrogen in bipyridine. Combining in-situ characterization with computational calculations, we reveal that compared to COF-BD1 containing two diversion charge transfer pathways, the charge transfer pathway in COF-BD2 is confined to a confluence one due to the electron-deficiency effect of nitrogen, which greatly accelerates the intermolecular and out-of-plane charge transfer. Via effectively reducing the energy barrier of rate-determining water oxidation reaction, the subsequent water oxidation process to produce key *OH intermediate in COF-BD2 is also greatly facilitated, boosting the yield of H2O2 (5211 μmol g-1 h-1) from water, oxygen, and light without sacrificial agents or additional energy consumption. We further demonstrate that H2O2 can be efficiently produced by COF-BD2 in broad pH range, in real water, and in enlarged reactor with using natural sunlight for water decontamination.

The proliferation and spread of antibiotic-resistant bacteria (ARB) significantly threaten human health and ecosystem. Periodate (PI) based advanced oxidation process has potentials for water purification but limited by complex activators or activation process. Herein, we demonstrated that H2O2 could be used to activate PI, achieving efficient ARB disinfection performance. Particularly, we found that the PI/H2O2 system (0.1 mM for both oxidants) could inactivate ARB (Escherichia coli) within 35 min. The intracellular defense system attacked by HO· radicals generated in the disinfection system, resulting in the inactivation of ARB. Antibiotic resistance genes (ARGs) released with the lysis of cell membrane could be further degraded by HO· radicals. Moreover, we found that the PI/H2O2 system was effective to inactivate ARB in a broad range of ionic strengths, with coexisting common ions and humic acid, as well as in four typical actual water bodies. The PI/H2O2 system could also efficiently disinfect other types of bacteria and degrade typical organic contaminants. In addition, under sunlight irradiation, the ARB inactivation performance of the PI/H2O2 system could be greatly improved. This study provided a practical and efficient way for decontaminating ARB/ARGs-polluted water.