摘要

       纳米材料的潜在风险和抗生素抗性基因（ARGs）的传播已成为全球公众关注的两大问题。研究证实，纳米氧化铝可以促进质粒介导的ARGs的传播。纳米二氧化钛（TiO2）是一种优异的光催化纳米材料，应用广泛，常存在于水环境中。在各种纳米材料浓度、细菌密度、消光时间和消光温度下，纳米二氧化钛均能显着促进 RP4 质粒在大肠杆菌中的结合。我们开发了一个数学模型来定量描述共轭过程，并使用该模型来评估纳米二氧化钛对 ARG 扩散的影响。我们获得了总细菌和抗性细菌的分析解决方案，这些解决方案通过使用 qPCR 的质粒和染色体特有的遗传位点的丰度进行计数。我们的结果表明，该数学模型能够很好地拟合实验数据，可用于定量评估纳米二氧化钛的效果。根据我们的模型，纳米 TiO2 的存在将细菌生长速率从 0.0360 降低到 0.0323 min−1 并将共轭转移速率从 6.69 × 10−12 增加到 3.93 × 10−10 mL 细胞−1 细胞−1这些结果表明纳米二氧化钛同时抑制细菌生长并促进结合。形态学和mRNA表达的数据也证明了这种现象。我们的结果证实，环境纳米二氧化钛可能会导致 ARG 的传播，从而造成环境风险。此外，我们提供了一种潜在的方法来监测由缀合引起的 ARG 的变化，并评估抗菌物质对 ARG 表达的影响。

       The potential risks of nano-materials and the spread of antibiotic resistance genes (ARGs) have become two major global public concerns. Studies have confirmed that nano-alumina can promote the spread of ARGs mediated by plasmids. Nano-titanium dioxide (TiO2), an excellent photocatalytic nano-material, has been widely used and is often present in aqueous environments. At various nano-material concentrations, bacterial density, matting time, and matting temperature, nano-TiO2 can significantly promote the conjugation of RP4 plasmid in Escherichia coli. We developed a mathematical model to quantitatively describe the conjugation process and used this model to evaluate the effects of nano-TiO2 on the spread of ARGs. We obtained analytical solutions for total and resistant bacteria, which were enumerated by the abundance of genetic loci unique to the plasmid and the chromosome using qPCR. Our results showed that the mathematic model was able to fit the experimental data well and can be used to quantitatively evaluate the effects of nano-TiO2. According to our model, the presence of nano-TiO2 decreased the bacterial growth rate from 0.0360 to 0.0323 min−1 and increased the conjugative transfer rate from 6.69 × 10−12 to 3.93 × 10−10 mL cell−1 min−1. These results indicate that nano-TiO2 inhibited bacterial growth and promoted conjugation simultaneously. The data for morphology and mRNA expression also demonstrated this phenomenon. Our results confirm that environmental nano-TiO2 may cause the spread of ARGs and thus poses an environmental risk. In addition, we provide a potential method for monitoring changes in ARGs that result from conjugation and evaluating the effects of antimicrobial substances on ARG expression.

https://www.tandfonline.com/doi/abs/10.3109/17435390.2014.991429