陕北地区石油污染土壤中不动杆菌属的筛选、鉴定及降解性能

Identification and oil-degrading performance of Acinetobacter sp. isolated from North Shaanxi oil-contaminated soil

从陕北地区石油污染土壤中分离鉴定得到两株不动杆菌属(Acinetobacter sp.)的高效石油降解菌A.sp 1和A.sp 2,分别从盐浓度、pH值、氮源、磷源和接种量等因素进行研究以确定其最佳石油降解条件,并进一步通过GC-MS(Gas ChromatographyMass Spectrometer)方法分析其在最佳条件下对原油组分的不同降解性能。结果显示:A.sp 1在盐浓度为1%、pH值为6—7、磷源为KH2PO4和K2HPO4、氮源为尿素和接种量为4%的条件下,最高降解率可达到60%。A.sp 2在盐浓度为1%、pH值为7—9、磷源为KH2PO4和K2HPO4、氮源为硝酸铵和接种量为8%的条件下,最高降解率可达到67%。GC-MS分析结果表明,菌株A.sp 1对石油烃类C21—C25有明显的降解效果,菌株A.sp 2对石油烃类C20—C30的降解效果较好。

Currently, the accidental releases of petroleum products are of particular concern in the environment. Hydrocarbon contamination is one of the major problems facing industrialized nations today resulting from the activities related to the petrochemical industry. Hydrocarbon contamination may produce toxic effects such as ecotoxicity and carcinogenic risk on the soil and water, and on the human body such as the central nervous system, liver, kidneys, heart, and so forth. The process of bioremediation has been defined as the use of microorganisms to detoxify or remove pollutants owing to their diverse metabolic capabilities and is also an evolving method for the removal and degradation of many environmental pollutants including the products of petroleum industry. It is believed that many indigenous microorganisms in water and soil are capable of degrading hydrocarbon contaminants. Bioremediation functions basically on biodegradation, transforming complex organic contaminants to other simpler organic compounds by biological agents like microorganisms. Biodegradation of petroleum hydrocarbons is a complex process that depends on the nature and the amount of the hydrocarbons present, while biodegradation is relatively noninvasive and more economical than other remediation technologies such as chemical and physical methods. As bioremediation is cost-effective and would lead to complete mineralization, it is the promising technology for the treatment of these contaminated sites. Bacteria are the most active agents in petroleum degradation, and they work as primary degraders of spilled oil in environment. Numerous scientific articles have covered various factors that influence the rate of oil biodegradation. Different factors influencing hydrocarbon degradation have been reported previously. In this study, two strains of Acinetobacter, A.sp 1 and A.sp 2, efficiently capable of degrading crude oil were isolated from North Shaanxi oil-contaminated soil. The influence of the salinity, pH, different N, P sources and inoculation amount on the degradation of crude oil was separately studied to obtain the optimum degradation conditions, and the performance of these two strains under the optimum conditions on crude oil degradation were further separately investigated by GC-MS（Gas Chromatography-Mass Spectrometer） method. The results showed that A.sp 1 was able to efficiently degrade crude oil under the salt concentration of 1%, pH 6-7, KH2PO4 and K2HPO4 as phosphorus source, urea as nitrogen source, an inoculum ratio of 4%, respectively, and in which a degradating rate of 60% can be reached under the combined optimum conditions. A.sp 2 was observed to efficiently degrade crude oil under the salt concentration of 1%, pH 7-9, KH2PO4 and K2HPO4 as phosphorus source, ammonium nitrate as nitrogen source, an inoculum ratio of 8%, respectively, and in which a degradating rate of 67% can be obtained under the combined optimum conditions. GC-MS analysis showed that A.sp 1 was performed efficiently for the hydrocarbon C21-C25 components of the crude oil. A.sp 2 was shown to efficiently degrade the hydrocarbon C20-C30 components of the crude oil. Microbial degradation is the major and ultimate natural mechanism by which one can cleanup the petroleum hydrocarbon pollutants from the environment. Our results may be helpful to establish an efficient biodegradation strategy for Hydrocarbon contamination.