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Antibiotic resistance is a serious global threat for public health. Considering the high abundance of cell-free DNA encoding antibiotic resistance genes (ARGs) in both clinical and environmental settings, natural transformation is an important horizontal gene transfer pathway to transmit antibiotic resistance. It is acknowledged that antibiotics are key drivers for disseminating antibiotic resistance, yet the contributions of non-antibiotic pharmaceuticals on transformation of ARGs are overlooked. In this study, we report that some commonly consumed non-antibiotic pharmaceuticals, at clinically and environmentally relevant concentrations, significantly facilitated the spread of antibiotic resistance through the uptake of exogenous ARGs. This included nonsteroidal anti-inflammatories, ibuprofen, naproxen, diclofenac, the lipid-lowering drug, gemfibrozil, and the β-blocker propranolol. Based on the results of flow cytometry, whole-genome RNA sequencing and proteomic analysis, the enhanced transformation of ARGs was affiliated with promoted bacterial competence, enhanced stress levels, over-produced reactive oxygen species and increased cell membrane permeability. In addition, a mathematical model was proposed and calibrated to predict the dynamics of transformation during exposure to non-antibiotic pharmaceuticals. Given the high consumption of non-antibiotic pharmaceuticals, these findings reveal new concerns regarding antibiotic resistance dissemination exacerbated by non-antibiotic pharmaceuticals.

Antibiotic resistance is a global threat to public health. The use of antibiotics at sub-inhibitory concentrations has been recognized as an important factor in disseminating antibiotic resistance via horizontal gene transfer. Although non-antibiotic, human-targeted pharmaceuticals are widely used by society (95% of the pharmaceuticals market), the potential contribution to the spread of antibiotic resistance is not clear. Here, we report that commonly consumed, non-antibiotic pharmaceuticals, including nonsteroidal anti-inflammatories (ibuprofen, naproxen, diclofenac), a lipid-lowering drug (gemfibrozil), and a β-blocker (propranolol), at clinically and environmentally relevant concentrations, significantly accelerated the dissemination of antibiotic resistance via plasmid-borne bacterial conjugation. Various indicators were used to study the bacterial response to these drugs, including monitoring reactive oxygen species (ROS) and cell membrane permeability by flow cytometry, cell arrangement, and whole-genome RNA and protein sequencing. Enhanced conjugation correlated well with increased production of ROS and cell membrane permeability. Additionally, these non-antibiotic pharmaceuticals induced responses similar to those detected when bacteria are exposed to antibiotics, such as inducing the SOS response and enhancing efflux pumps. The findings advance understanding of the transfer of antibiotic resistance genes, emphasizing the concern that non-antibiotic, human-targeted pharmaceuticals enhance the spread of antibiotic resistance among bacterial populations.

A pressurized chemical-looping combustion combined cycle (PCLC) system is proposed for solid fuels combustion with potential high system efficiency, improving the fuel conversion and lowering the cost for CO 2 sequestration. In this study, pressurized CLC of coal with Companhia Valedo Rio Doce (CVRD) iron ore was investigated in a laboratory fixed bed reactor focusing on cyclic performance. CVRD iron ore particles were exposed alternately for 20 cycles to reduction by 0.4 g of Chinese Xuzhou bituminous coal gasified with 87% steam/N 2 mixture and oxidation with 5% O 2 in N 2 at 970 °C at atmospheric pressure (0.1 MPa) and a typical elevated pressure of 0.5 MPa. With increasing number of redox cycles, more pyrolysis gases are oxidized by the oxygen carrier. At elevated pressure, the char gasification is intensified with negligible gasification intermediate products released. The CO 2 fraction increases from 80% to approximate 90% after 10 cycles at atmospheric pressure. At elevated pressures, the average CO 2 fraction stabilizes at 95.75%, approximate to the equilibrium value. The carbon conversion at 0.1 MPa and 0.5 MPa is 76.48 and 84.65%, respectively, and maintains approximately the same during the cycles because excessive steam gasification agent used in this study. The oxygen carrier conversion determined from the oxygen mass balance verifies that reduction level increases with the cycle number. The physical and chemical properties of oxygen carrier particles were characterized. X-ray diffraction (XRD) analysis verifies the extent of reduction level increases with cycles. No detectable formation of compound of iron oxide and coal ash was observed. Scanning electron microscope (SEM) analyses show that the iron ore particles become porous and that more pores formed with cycles. Agglomeration of particles was not observed in all experiments at both pressures. Energy-dispersive X-ray spectroscopy (EDX) analysis show an increasing amount of coal ash on the oxygen carrier particles with increasing numbers of cycles. Pore size analyses show that the oxygen carrier particles maintained mesopores for both atmospheric and elevated pressure. The increase of both surface area and pore volume illustrates that the particles become more porous with redox cycles. This study show that pressurized CLC of coal is promising and a low-cost iron ore-based oxygen carrier may be suitable for pressurized CLC of coal.

The bacterial infection that involves antimicrobial resistance is a rising global threat to public health. Chlorine-based water disinfection processes can inactivate antibiotic resistant bacteria. However, at the same time, these processes may cause the release of antibiotic resistance genes into the water as free DNA, and consequently increase the risk to disseminate antibiotic resistance via natural transformation. Presently, little is known about the contribution of residual chlorine affecting the transformation of extracellular antibiotic resistance genes (ARGs). This study investigates whether chloramine and free chlorine promote the transformation of ARGs and how this may occur. We reveal that both chloramine and free chlorine, at practically relevant concentrations, significantly stimulated the transformation of plasmid-encoded ARGs by the recipient Acinetobacter baylyi ADP1, by up to a 10-fold increase. The underlying mechanisms underpinning the increased transformations were revealed. Disinfectant exposure induced a series of cell responses, including increased levels of reactive oxygen species (ROS), bacterial membrane damage, ROS-mediated DNA damage, and increased stress response. These effects thus culminated in the enhanced transformation of ARGs. This promoted transformation was observed when exposing disinfectant-pretreated A. baylyi to free plasmid. In contrast, after pretreating free plasmid with disinfectants, the transformation of ARGs decreased due to the damage of plasmid integrity. These findings provide important insight on the roles of disinfectants affecting the horizontal transfer of ARGs, which could be crucial in the management of antibiotic resistance in our water systems.

Chemical-looping combustion (CLC), employing metal oxide(s) as the oxygen carrier for solid fuels (such as coal and biomass) combustion, is of growing interest thanks to its low cost of CO2 capture and the high system conversion efficiency. In this work, Fe2O3-containing wastes from the steel industry were applied as the oxygen carrier for chemical looping combustion with a Chinese bituminous coal in a bench-scale fixed-bed reactor. The performance of Fe2O3-containing industrial wastes was estimated with comparison to that of two other commercial iron ores (MAC iron ore from Australia and CVRD iron ore from Brazil). Effects of the operating pressure of the system (from 0.1 to 0.5 MPa) and cycle number (0–20) on the performance of the oxygen carriers were extensively studied, in terms of overall gas composition, carbon conversion, and its conversion rate. The Fe2O3-containing industrial wastes were remarkably sensitive with the operating pressure, as more pyrolysis gases and char gasification products were converted under higher pressure leading to higher concentration of CO2 and lower concentrations of CO and CH4. The elevated pressure also increased the carbon conversion and the overall reaction rate. The reactivity and porosity of the Fe2O3-containing industrial wastes under atmospheric pressure were notably enhanced by the reduction cycles, giving the concentration of 99% CO2 and the carbon conversion 81.41% after 20 cycles. Comparatively, the Fe2O3-containing industrial wastes exhibited better performance as oxygen carrier than the other two iron ores (MAC iron ore and CVRD iron ore), while the two iron ores behaved similarly to the Fe2O3-containing industrial waste with regard to the variation of operating pressure and cycles. It could be concluded that the Fe2O3-containing industrial wastes would be the outstanding oxygen carrier for chemical-looping combustion of coal over the other two iron ores.

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