Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China; Guangdong Provincial Key Laboratory of Environmental Protection Microbiology and Regional Ecological Security, Guangzhou 510070, China.
Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China; Guangdong Provincial Key Laboratory of Environmental Protection Microbiology and Regional Ecological Security, Guangzhou 510070, China.
J Hazard Mater. 2024 Dec 5;480:135902. doi: 10.1016/j.jhazmat.2024.135902. Epub 2024 Sep 18.
Extracellular polymeric substances (EPS) are tightly related to the horizontal gene transfer (HGT) of antibiotic resistance genes (ARGs), but often neglected in soil. In this study, nanoscale zero-valent iron (nZVI) was utilized for attenuation of ARGs in contaminated soil, with an emphasis on its effects on EPS secretion and HGT. Results showed during soil microbe cultivation exposed to tetracycline, more EPS was secreted and significant increase of tet was observed due to facilitated HGT. Notably, copies of EPS-tet accounted for 71.39 % of the total tet, implying vital effects of EPS on ARGs proliferation. When co-exposed to nZVI, EPS secretion was decreased by 38.36-71.46 %, for that nZVI could alleviate the microbial oxidative stress exerted by tetracycline resulting in downregulation of genes expression related to the c-di-GMP signaling system. Meanwhile, the abundance of EPS-tet was obviously reduced from 7.04 to 5.12-6.47 log unit, directly causing decrease of total tet from 7.19 to 5.68-6.69 log unit. For the reduced tet, it was mainly due to decreased EPS secretion induced by nZVI resulting in inhibition of HGT especially transformation of the EPS-tet. This work gives an inspiration for attenuation of ARGs dissemination in soil through an EPS regulation strategy.
胞外聚合物（EPS）与抗生素抗性基因（ARGs）的水平基因转移（HGT）密切相关，但在土壤中往往被忽视。在本研究中，纳米零价铁（nZVI）被用于衰减污染土壤中的 ARGs，重点研究其对 EPS 分泌和 HGT 的影响。结果表明，在四环素暴露下的土壤微生物培养过程中，由于 HGT 的促进，更多的 EPS 被分泌，四环素的浓度显著增加。值得注意的是，EPS-四环素的拷贝数占总四环素的 71.39%，这意味着 EPS 对 ARGs 增殖有重要影响。当与 nZVI 共同暴露时，EPS 分泌减少了 38.36-71.46%，因为 nZVI 可以减轻四环素对微生物的氧化应激，从而下调与 c-di-GMP 信号系统相关的基因表达。同时，EPS-四环素的丰度明显从 7.04 减少到 5.12-6.47log 单位，直接导致总四环素从 7.19 减少到 5.68-6.69log 单位。对于减少的四环素，主要是由于 nZVI 诱导的 EPS 分泌减少，从而抑制了 HGT，特别是 EPS-tet 的转化。这项工作为通过 EPS 调控策略衰减土壤中 ARGs 的传播提供了启示。
