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Considering the widespread application of nanotechnology in the food industry, humans are increasingly exposed to food-related engineered nanoparticles (NPs). Upon ingestion, NPs come into contact with human commensal bacteria that play an important role in human health and disease. Therefore, the effects and biotransformation of food-related NPs in the digestive tract, including microbiota, need to be assessed. Herein, artificial saliva was used as a physiologically relevant test medium to investigate the effects of Ag, SiO2and TiO2NPs and food-grade TiO2on the growth and antagonistic activity of Streptococcus salivariusK12, a human beneficial bacterium inhabiting the oral cavity, and bacterially induced biotransformation of NPs. SiO2NPs, TiO2NPs and food-grade TiO2at concentrations up to 100 mg L−1did not affect the growth of S. salivariusK12, while Ag NPs were expectedly growth-inhibitory already at 10 mg L−1, both in aerobic and anaerobic conditions. At sub-growth-inhibitory concentrations, NPs and food-grade TiO2significantly modified the transcription of structural genes (salAand sboA) of two bacteriocins (salivaricins) in S. salivariusK12 genome, signal transduction gene (sboK) and bacteriocin immunity conferring gene (sboG, an ABC transporter). Changes in gene expression were accompanied by the increased antagonistic activity of the bacterial strain. Spent artificial saliva, where bacteria had been cultured, markedly affected the transformation of NPs compared to fresh artificial saliva. The transformations included significant agglomeration, increased dissolution of Ag NPs and enhanced bioavailability of SiO2NPs, TiO2NPs and food-grade TiO2, while Ag NPs became less toxic. The results showed that food-related NPs can affect beneficial bacterial traits needed for competitiveness in microbiota and bacterial activity influences the transformation of NPs, potentially affecting the fate and toxicity of NPs in the digestive tract.

Despite available technology and the knowledge that chemical pollution damages human and ecosystem health, chemical pollution remains rampant, ineffectively monitored, rarely prevented, and only occasionally mitigated. We present a framework that helps address current major challenges in the monitoring and assessment of chemical pollution by broadening the use of the sentinel species Daphniaas a diagnostic agent of water pollution. And where prevention has failed, we propose the application of Daphniaas a bioremediation agent to help reduce hazards from chemical mixtures in the environment. By applying “omics” technologies to Daphniaexposed to real-world ambient chemical mixtures, we show improvements at detecting bioactive components of chemical mixtures, determining the potential effects of untested chemicals within mixtures, and identifying targets of toxicity. We also show that using Daphniastrains that naturally adapted to chemical pollution as removal agents of ambient chemical mixtures can sustainably improve environmental health protection. Expanding the use of Daphniabeyond its current applications in regulatory toxicology has the potential to improve both the assessment and the remediation of environmental pollution.

Occurrence of brominated flame retardants especially tetrabromobisphenol A (TBBPA) in water bodies poses a serious threat to aquatic ecosystems. Heterogeneous photocatalysis is a versatile technology that can efficiently degrade organic contaminants. However, existing studies on photocatalytic degradation of TBBPA are all achieved under intense light irradiation and high initial concentrations of TBBPA, which are far from real environmental conditions and not conducive to practical application. In this study, series of Z-scheme heterojunctions of WO3/ZnIn2S4photocatalysts were prepared and used for the high-efficiency photocatalytic degradation of TBBPA at lower light irradiation intensity (100 W) and lower TBBPA concentration (5.4 mg/L). Among them, WO3/ZnIn2S4-3 (molar ratio of 1:3) exhibited the highest photocatalytic activity due to the formation of Z-Scheme heterojunction which effectively facilitated the separation of photogenerated charges and endowed WO3/ZnIn2S4-3 higher redox ability. Thus, under light illumination, 91.6% degradation of TBBPA was achieved at an initial pH of 8.0 within 150 min, with a pseudo-first-order rate constant of 0.01572 min−1. Electron spin resonance spectroscopy and radical scavenger experiments confirmed that ·O2−radicals were the primary reactive oxygen species driving the TBBPA degradation. By applying LC-MS/MS, the degradation products were identified and possible degradation pathways were proposed. Finally, potential toxicity for PBBPA and generated intermediates were evaluated using luminescent bacteria, which revealed the toxicity of PBBPA was reduced effectively during the photocatalytic degradation process. Overall, the Z-scheme WO3/ZnIn2S4photocatalyst provides a promising way for the application of photocatalytic technology in actual wastewater treatment.