Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou 310014, China.
Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou 310014, China.
J Hazard Mater. 2021 Aug 15;416:125728. doi: 10.1016/j.jhazmat.2021.125728. Epub 2021 Mar 23.
Antibiotic contamination and antibiotic resistance have caused growing concerns in different aquatic environments. This work investigated the complexation between tetracycline chloride (TCH) and the molecular weight (MW)-fractionated root exudates - the key abiotic mechanism impacting antibiotic fate and antibiotic resistance in rhizosphere. Results show that the affinity of TCH to the high MW exudates (≥10 kDa) facilitated the TCH deposition on roots and meanwhile reinforced the expression of certain tetracycline resistance genes (i.e. tetA) and the growth of tetracycline resistant bacteria. The interaction between TCH and the lower MW exudates (<10 kDa) completely inhibited the bacteria growth even below the minimum inhibitory concentration of TCH. In microcosms, the abiotic interaction between TCH and root exudates made effects along with biotic processes. Persistent TCH stimulation (≥50 µg/L, 7 d) induced the change of tet gene abundance and bacteria phyla composition though the mediation of root exudates made the rhizosphere less sensitive to the TCH stress. Summarily, the affinity of antibiotics to root exudates varied with MWs, which was closely related to (i) the antibiotic fate in the root mucus layer, (ii) the bacteria inhibition capacity of antibiotics, and (iii) the antibiotic resistance and bacterial community.
抗生素污染和抗生素耐药性在不同的水生环境中引起了越来越多的关注。本研究探讨了四环素盐酸盐（TCH）与分子量（MW）分级的根分泌物之间的络合作用-影响根际抗生素命运和抗生素抗性的关键非生物机制。结果表明，TCH 与高分子量分泌物（≥10 kDa）的亲和力促进了 TCH 在根上的沉积，同时增强了某些四环素耐药基因（如 tetA）的表达和四环素耐药菌的生长。TCH 与低分子量分泌物（<10 kDa）之间的相互作用完全抑制了细菌的生长，甚至低于 TCH 的最小抑菌浓度。在微宇宙中，TCH 与根分泌物之间的非生物相互作用与生物过程一起产生影响。持续的 TCH 刺激（≥50 µg/L，7 d）通过根分泌物的介导改变了 tet 基因丰度和细菌门组成，使根际对 TCH 胁迫的敏感性降低。总之，抗生素与根分泌物的亲和力随 MW 而变化，这与（i）抗生素在根粘液层中的命运、（ii）抗生素对细菌的抑制能力以及（iii）抗生素耐药性和细菌群落密切相关。
