表面活性剂强化节杆菌降解PAHs的信号通路及分子机制

This project aims to elucidate the molecular mechanism of signal recognition and transduction in surfactant-enhanced biodegradation of PAHs by a Gram positive bacterium, Arthrobacter sp. SA02. From the gene expression, the chemical mechanisms of the signal pathway in surfactant-mediated membrane fluidity and the expression of biodegrading genes were explored. The combined technology with transcriptome and proteomics was employed to investigate the key genes, proteins and potential signal pathway involved in surfactant-mediated membrane fluidity and the expression of biodegrading genes. In additionally, the superamolecular system proteoliposome that can express the cell signal and transduction in vitro, was established to verify the functional mechanisms of the signal recognition and transduction of the proteins expressed by the key genes, combined with the fluorescence resonance energy transfer technology and molecular docking technology. This project would be expected to reveal a better and detailed mechanistic understanding of the signal pathway in surfactant-enhanced biodegradation of PAHs by the indigenous microorganism, and in turn help to select surfactant or surfactant coexisted in soil to more efficiently regulate the biodegradation process of the hydrophobic organic pollutants through the interrelated microinterface processes, such as the adsorption at the microinterface between soil and microbial cells, transmembrane transportation and intracellular biodegradation. Also, it would be expected to provide scientific basis to develop a simple, economic and efficient surfactant-enhanced bioremediation technology.

本项目旨在探明表面活性剂强化节杆菌SA02(Arthrobacter sp. SA02)降解PAHs过程中信号识别与传导的分子机制。拟从基因表达入手，重点探讨表面活性剂调控细胞膜流动性和降解基因表达信号通路的化学机制。利用转录组学和蛋白组学联合技术分析表面活性剂改变该菌细胞膜流动性和降解基因表达信号识别、传导的关键调控基因、蛋白及信号通路；构建能表达细胞信号并传导的体外超分子体系蛋白脂质体，借助荧光共振能量转移技术和分子对接技术分析和验证关键调控基因所表达蛋白的信号识别与传导的作用机制。试图从分子水平上深入理解表面活性剂强化土著微生物降解PAHs信号通路的微观机制，将有助于选择表面活性剂或利用土壤共存的表面活性剂更有效地调控疏水性有机污染物在土壤-土著微生物细胞界面吸附、跨膜和胞内降解三个微界面过程，为发展简单、经济和高效的表面活性剂强化生物修复技术提供科学依据。

表面活性剂的大量使用后可进入土壤环境，导致土壤中多环芳烃和微生物在土壤中共存，利用共存的表面活性剂发展强化生物修复技术将是具有发展前景的强化生物修复技术。然而，表面活性剂强化生物修复技术受限于作用机制不清，限制了其在土壤修复中的应用。本项目发现菲降解菌SA02的sigma 70因子能感知阴离子表面活性剂十二烷基苯磺酸钠SDBS浓度变化和菲浓度的变化，从而调控细胞膜流动性相关的脂肪酸脱饱和酶基因（△9Dase）和菲降解基因（RHDase）的表达，进而提高了SA02菌细胞膜流动性，促进更多的菲分子经细胞膜进入细胞，并由此增加了SA02菌对菲的降解。这说明SA02菌的sigma 70因子是SDBS影响菲降解过程的重要调控基因，也是信号传导的重要途径。本项目的研究结果为发展基于表活性剂强化微生物修复的土壤有机污染修复技术提供了理论支撑。