School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, PR China; Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012, PR China; Instrumental Analysis Center of Zhejiang Gongshang University, Hangzhou 310012, PR China.
School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012, PR China; Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012, PR China.
Ecotoxicol Environ Saf. 2021 Jul 1;217:112240. doi: 10.1016/j.ecoenv.2021.112240. Epub 2021 Apr 23.
Quorum sensing (QS) plays an important role in the intensive communication between plants and microbes in the rhizosphere during the phytoremediation. This study explored the influence of the root exudates of hyperaccumulator Sedum alfredii on Pseudomonas aeruginosa based on QS. The effects of the components of root exudates, genes expression and transcription regulation of QS system (especially the las system) in Pseudomonas aeruginosa wild-type strain (WT) and rhl system mutant strain (ΔrhlI) were systematically analyzed and discussed. The WT and ΔrhlI exposed to gradient root exudates (0×, 1×, 2×, 5× and 10×) showed a concentration-corrective inhibition on protease production, with the inhibition rates of 51.4-74.5% and 31.2-50.0%, respectively. Among the components of the root exudates of Sedum alfredii, only thymol had an inhibition effects to the root exudates on the activity of protease and elastase. The inhibition rates of 50 μmol/L thymol on protease and elastase in WT were 44.7% and 24.3%, respectively, which was consistent with the variation in ΔrhlI. The gene expression of lasB declined 36.0% under the 1× root exudate treatment and 73.0% under the 50 μmol/L thymol treatment. Meanwhile, there was no significant impact on N-3-oxo-dodecanoyl-L-homoserine lactone signal production and the gene expression of lasI and lasR. Therefore, thymol from Sedum alfredii root exudates could inhibit the formation of protease and elastase in Pseudomonas aeruginosa by suppressing the expression of lasB, without any significant influence on the main las system as a potential natural QS inhibitor.
群体感应（QS）在植物修复过程中根际植物与微生物的强化通讯中起着重要作用。本研究基于 QS 探讨了超积累植物垂盆草根系分泌物对铜绿假单胞菌的影响。系统分析和讨论了根系分泌物成分、QS 系统（特别是 las 系统）基因表达和转录调控对铜绿假单胞菌野生型（WT）和 rhl 系统突变型（ΔrhlI）的影响。WT 和 ΔrhlI 暴露于梯度根系分泌物（0×、1×、2×、5×和 10×）中，对蛋白酶的产生表现出浓度校正抑制作用，抑制率分别为 51.4%-74.5%和 31.2%-50.0%。在垂盆草根际分泌物的成分中，只有百里香酚对根系分泌物的蛋白酶和弹性蛋白酶活性有抑制作用。50μmol/L 百里香酚对 WT 中蛋白酶和弹性蛋白酶的抑制率分别为 44.7%和 24.3%，与ΔrhlI 的变化一致。lasB 的基因表达在 1×根系分泌物处理下下降了 36.0%，在 50μmol/L 百里香酚处理下下降了 73.0%。同时，对 N-3-氧代十二酰基-L-高丝氨酸内酯信号产生和 lasI 和 lasR 的基因表达没有显著影响。因此，垂盆草根际分泌物中的百里香酚通过抑制 lasB 的表达来抑制铜绿假单胞菌蛋白酶和弹性蛋白酶的形成，作为一种潜在的天然 QS 抑制剂，对主要的 las 系统没有显著影响。
