摘要
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通过质粒介导的缀合进行抗生素抗性基因的水平基因转移（HGT）对全球公共健康构成了重大威胁。生物炭是一种广泛使用的环境修复材料，对ARGs的命运有着显著的影响。然而，尽管有报道称生物炭能够通过结合和转化抑制ARGs的HGT，但对介导抑制作用的细胞内过程知之甚少。另一方面，作为典型的天然有机物，黄腐酸是一种常见的环境影响因素，它如何干扰生物炭对ARGs HGT的影响尚不清楚。因此，本研究研究了在三种温度下热解的生物炭和用黄腐酸包裹的相应生物炭对携带质粒RP4的大肠杆菌MG1655和大肠杆菌HB101之间ARGs偶联转移的影响。结果表明，热解温度越高的生物炭对RP4质粒的偶联转移具有更大的抑制作用。生物炭的抑制作用主要归因于（i）由于三磷酸腺苷（ATP）能量供应受到抑制，质粒转移基因表达下调，包括偶联转移通道的形成和质粒复制；（ii）细胞膜通透性降低。相反，黄腐酸涂层减少了生物炭的这种抑制作用，主要是通过提供更多的ATP和加强细胞内活性氧（ROS）的防御。我们的发现揭示了介导生物炭对ARGs偶联转移影响的细胞内过程，这将为使用生物炭减少ARGs的传播提供支持。
Abstract
Abstract Image
Horizontal gene transfer (HGT) of antibiotic resistance genes (ARGs) through plasmid-mediated conjugation poses a major threat to global public health. Biochar, a widely used environmental remediation material, has remarkable impacts on the fate of ARGs. However, although biochar was reported being able to inhibit the HGT of ARGs via conjugation and transformation, little is known about the intracellular process that mediates the inhibition effects. On the other hand, as typical natural organic matter, fulvic acid is a common environmental influencer, and how it interferes with the effect of biochar on the HGT of ARGs is unknown. Therefore, this study investigated the effects on the conjugative transfer of ARGs between Escherichia coli MG1655 and E. coli HB101 carrying plasmid RP4, with biochars pyrolyzed at three temperatures and with the corresponding biochars coating with fulvic acid. Results showed that biochar with higher pyrolyzed temperature had a more substantial inhibitory effect on the conjugative transfer of the RP4 plasmid. The inhibitory effect of biochar was mainly attributed to (i) down-regulation of plasmid transfer gene expression, including the formation of conjugative transfer channel and plasmid replication, due to restrained adenosine triphosphate (ATP) energy supply and (ii) decreased cell membrane permeability. Conversely, the fulvic acid coating diminished this inhibition effect of biochar, mainly by providing more ATP and strengthening intracellular reactive oxygen species (ROS) defense. Our findings shed light on the intracellular process that mediates the effects of biochar on the conjugative transfer of ARGs, which would provide support for using biochar to reduce the spread of ARGs.

https://pubs.acs.org/doi/abs/10.1021/acs.est.2c02701