【摘要】 嗜冷菌、嗜盐菌、耐重金属菌、耐重油菌等极端微生物广泛存在于极地高寒、盐碱地以及存在重金属、重油等污染的毒性污染土壤中,是胁迫条件下石油烃降解与转化的重要微生物资源。文章从适应机制、降解机理、降解特性、修复实践等角度出发,综述了低温、盐碱、重金属、重油等不同胁迫条件下的石油烃污染土壤微生物修复进展。在石油烃降解机理方面,微生物细胞与油滴的附着机制尚不清楚,而生物表面活性剂的产生和作用机制已经得到了很好的研究。嗜冷菌的适冷机制与细胞膜脂类组成、冷激蛋白、冷适应蛋白、嗜冷酶、能量代谢等有关,低温(15℃)时石油烃降解效率可达70%以上。嗜盐菌具备细胞外被隔离机制和离子反向运输机制,能产生渗透压调节剂、具有独特的渗透压平衡方式,NaCl浓度为30g·L-1时石油烃的降解效率可达60%以上。石油烃降解菌对重金属的耐受机制包括生物吸附、细胞内积累、酶催化转化、生物浸出和生物矿化、氧化还原反应等过程,会影响土壤中重金属的迁移率和生物有效性,提高作物的产量和对重金属的富集。微生物吸收重油的机制包括界面张力降低、选择性堵塞、粘度降低、生物降解和润湿性改变等,对重质原油的总体降解率可达70%以上,但是对其中沥青质单一组分的历史最高生物降解率仅为48%。利用极端微生物修复极端、胁迫条件下的石油污染土壤,应加强菌种培育、未明机制探索、重油组分(沥青质和树脂)降解、风险评估、修复工艺参数优化及推广应用等工作。更多还原

【Abstract】 Extremophiles such as psychrophile, halophilic bacteria, heavy-metal-adapted bacteria, heavy-oil-adapted bacteria which widely exists in polar alpine, saline and alkaline areas, as well as polluted soil with heavy metals and heavy oil, are the important microorganisms for petroleum hydrocarbons biodegradation under stress conditions. In this paper, we reviewed microbial remediation of petroleum hydrocarbon contaminated soil under different stress conditions such as low temperature, saline-alkali,heavy metal and heavy oil in terms of adaptation mechanism, degradation mechanism, degradation properties, and remediation application. Although the interaction mechanism between microbial cells and oil droplets during petroleum hydrocarbon degradation has still not well understood, the mechanisms relating to biosurfactants production has been well illustrated. It has been reported that cold-tolerance mechanism of psychrophilic bacteria are associated with lipid composition of cell membrane, cold shock protein,cold-tolerance protein, psychrophilic enzyme, energy metabolism and so on, contributing to above 70% of the petroleum hydrocarbon degradation efficiency at a low temperature(15 ℃). On the other hand, halophilic bacteria possess cell coat isolation mechanism and ion transport/antiport mechanism, and can produce osmotic pressure regulator for balancing cell osmotic pressure.For example, the degradation efficiency of petroleum hydrocarbon can reach over 60% at 30 g·L-1 NaCl. Heavy metal tolerance of soil microorganisms can be achieved via several mechanisms such as biosorption, intracellular accumulation, enzyme-catalyzed transformation, bioleaching and biomineralization, redox reactions. These mechanisms can enhance metal mobility and bioavailability in soil, and promote crop yields and heavy metal accumulation in crops. The key microbial heavy oil-recovery mechanisms are interfacial tension reduction, selective plugging, viscosity reduction, biodegradation and wettability alteration. The results in the literatures showed that the total degradation rate of heavy crude oil were more than 70%, while the highest asphaltene biodegradation rate was only 48%. Towards highly-effective extremophiles bioremediation of petroleum hydrocarbon-contaminated soils under stress conditions, future research should be focused on improvement in strain cultivation, unknown mechanism exploration, degradation of heavy petroleum components(asphaltenes and resins), risk assessment, process parameters optimization and remedial actions, etc.更多还原