微生物-矿物颗粒互作界面多环芳烃的厌氧微生物降解机制

Environment contaminated by polycyclic aromatic hydrocarbons (PAHs) emissions and accumulation in aquatic sediments due to industrial development and increase in energy consumption is becoming increasingly degenerative. In sedimentary environments, biodegradation by anaerobic microorganism plays an important role in natural attenuation of PAHs. Clay particles are the important solid-phase mineral components in sedimentary environments. Microbes-minerals interactions exert an important influence on contaminant bioavailability and extracellular electron transfer, thus changing the process of biodegradation. However, the influence mechanisms of microbes-minerals interactions on microbial degradation of organic contaminant is largely unknown. Geobacter sp., a higly-efficient phenanthrene anaerobic degrading bacteria, will be employed; the representative iron-bearing clay minerals (nontronite, illite and chlorite) are selected. The effects of microbes-minerals interactions on bioavailability of phenanthrene and extracellular electron transfer will be investigated by using classical chemical methods combined with modern analytical techniques including attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and microcalorimetry. The proposal aimed to clarify the effects of microbes-minerals interactions on the fate of PAHs in sedimentary environments and to provide scientific basis and technologic support for remediation of organic pollutants in contaminated sediments.

随着国内工业发展和能源消耗增加，大量PAHs排放并在水体沉积物中蓄积，带来的污染问题日益严重。在沉积物环境中，厌氧微生物主导的降解过程在PAHs自然衰减中发挥着重要作用。粘土矿物颗粒是沉积物中重要的固相组分，其与降解菌的互作会对污染物微生物有效性和胞外呼吸电子传递等降解环节产生重要影响，但相关机制尚不清楚。本项目选取沉积物环境中广泛存在的含铁粘土矿物（绿脱石、伊利石和绿泥石）和一株PAHs高效厌氧降解菌（Geobacter sp.）为材料，以多环芳烃代表物菲为目标污染物，运用经典化学方法和衰减全反射红外光谱、等温微量热等多种分析技术，研究细菌和粘土矿物相互作用对菲厌氧微生物吸收转化的影响，探讨粘土矿物颗粒在降解菌胞外电子传递中的作用，以期阐明微生物、矿物相互作用对沉积物中PAHs环境行为和归趋的影响机制，为沉积物环境中有机污染物修复提供科学依据和技术支撑。

厌氧环境中，矿物颗粒与微生物的互作会直接影响有机污染物微生物降解过程中的底物吸收和胞外电子传递等环节，从而改变其降解过程。基于此，本项目构建了可在分子水平研究细菌细胞界面行为的衰减全反射红外光谱观测系统，搭建了能够实时分析矿物表面微生物数量和活性的激光共聚焦显微镜技术平台，分析了电活性微生物在针铁矿表面的行为特征；通过还原动力学和微生物界面行为分析，首次研究了胞外黄素与针铁矿的相互作用对矿物微生物铁还原过程的影响；运用分子生物学和微生物/矿物界面互作分析技术，发现了一种新的铁（氢）氧化物对细胞外膜电子传递关键位点的堵塞机制，阐明了针铁矿抑制不同极性偶氮染料微生物还原的原因。研究解决了在粘土矿物颗粒表面的微生物行为难以观察的难题，为我们理解沉积物环境中电活性微生物的行为特征和相关环境效应提供了有效参考，并为厌氧环境有机污染物的去除提供了理论基础和技术依据。