摘要
      抗生素的滥用导致抗生素耐药性基因在环境中迅速传播，对生态系统和人类健康构成巨大威胁。在自然系统中应用生物炭来对抗ARGs的传播是一种引人注目的解决方案。不幸的是，由于对BC特性和细胞外ARGs转化之间相关性的了解不全面，BC的有效性仍然无法控制。为了确定关键因素，我们主要探讨了暴露于BC（在悬浮液或提取液中）的质粒介导的ARGs的转化行为、ARGs对BC的吸附能力以及BC对大肠杆菌的生长抑制。具体而言，强调了BC性质，包括颗粒尺寸（大颗粒150μm和胶体0.45–2μm）和热解温度（300、400、500、600和700°C）对ARGs转化的影响。结果表明，大颗粒BC和胶体BC，无论其热解温度如何，都会对ARGs转化产生显著的抑制作用，而BC提取溶液除了在300°C下热解外，几乎没有影响。相关分析表明，BC对ARGs转化的抑制作用与其对质粒的吸附能力密切相关。因此，具有较高热解温度和较小粒径的BCs的更大抑制作用主要来源于它们更大的吸附能力。有趣的是，大肠杆菌无法摄入吸附在BC上的质粒，这导致ARGs被阻断在细胞膜外，尽管这种抑制作用部分受到BC对大肠杆菌生存抑制的影响。特别是，在300°C下热解的大颗粒BC的提取溶液中可能发生显著的质粒聚集，导致ARGs转化的显著抑制。总的来说，我们的发现填补了对BC对ARGs转化行为影响的不足理解，并有可能为科学界缓解ARGs传播提供新的见解。
Abstract
Rampant use of antibiotics has caused a rapid dissemination of antibiotic resistance genes (ARGs) in environment, posing great threats to ecosystems and human health. Applying biochar (BC) in natural systems to combat the spread of ARGs arises as an attention-grabbing solution. Unfortunately, the effectiveness of BC is still unmanageable due to the incomprehensive knowledge over correlations between BC properties and extracellular ARGs transformation. To pinpoint the crucial factors, we primarily explored transformation behaviors of plasmid-mediated ARGs exposed to BC (in suspensions or extraction solutions), adsorption capacities of ARGs on BC, and growth inhibition of E. coli imposed by BC. Specifically, the effects of BC properties including particle size (large-particulate 150 μm and colloidal 0.45–2 μm) and pyrolytic temperature (300, 400, 500, 600, and 700 °C) on the ARGs transformation were emphasized. Results showed that both large-particulate BC and colloidal BC, irrespective of their pyrolytic temperature, would induce significant inhibitory effects on the ARGs transformation, while the BC extraction solutions showed little effect except BC pyrolyzed at 300 °C. Correlation analysis uncovered that the inhibition effect of BC on ARGs transformation was tightly correlated with its adsorption capacity towards plasmid. Accordingly, greater inhibitory effects from those BCs with higher pyrolytic temperatures and smaller particle sizes mainly originated from their greater adsorption capacities. Intriguingly, E. coli was unable to ingest the plasmid adsorbed on BC, which led to ARGs blocked outside the cell membrane, although this inhibitory effect was partially affected by survival inhibition of BC on E. coli. Particularly, significant plasmid aggregation could occur in the extraction solution of large-particulate BC pyrolyzed at 300 °C, leading to a significant inhibition of ARGs transformation. Overall, our findings complete the insufficient understanding over the effects of BC on ARGs transformation behavior, and potentially provide new insights to scientific communities in mitigating ARGs spreading.

https://www.sciencedirect.com/science/article/abs/pii/S0048969723015395