| Oil, also known as crude oil, is fossil fuels general formed by the organicresidues like animals and plants which are decomposed after a long time, and it ismostly founded in upper part of the earth’s crust. The composition of oil is verycomplicated, There are saturated alkanes, unsaturated alkanes, aromatic hydrocarboncompounds and bituminous material and so on, and it also contains thenonhydrocarbons such as compounds having O, N and S elements. As one of thenecessary energy for human existence and life, all countries in the world are in theexploitation of oil resources. But in the process of mining, transportation and using,the overflow and emissions of petroleum material can not be avoided. Petroleumhydrocarbons will pollute the ocean, the soil, underground water-surface watersystem, it also can threat to the survival and development of humans and othercreatures through the enrichment of the food chain and drinking water pollution,which influence the stability of the whole human society and ecological system.Bioremediation technology is developing rapidly in recent years because of itshuge advantage in the oil pollution treatment, and the application prospect ofmicroorganism in the environmental protection is becoming more and more wide.Domestic and overseas scholars have done a large number of related research inmicrobial remediation of ocean, soil and underground water oil pollution. Atpresent, a variety of oil degradation bacteria have been isolated, like Desulfovibrio,Pseudomonas, Alcaligenes, Flavobacterium and so on. In the mechanism of microbialdegradation of petroleum hydrocarbons, the factors influencing microbial remediationeffect and screening separation efficient strains, scholars have also done a lot ofresearch. And for a specific environment, domesticating a high efficient degradationbacteriacan which adapt to the environment is a great contribution in terms ofengineering application. In the northern areas of China, most of the microbialmetabolism is in the inhibition of state during the winter because of the lowtemperature in sewage treatment system, the ability of oil degradation is restricted too. Therefore, screening oil strains with high efficient degradation ability under the lowtemperature is very meaningful.This article screened25strains under the condition of low temperature withdiesel oil as the sole carbon source from aeration tank sludge of FushunPetrochemical Branch Company No.2Petroleum Factory. In the study ofdegradability we found that five bacterial strains had strong ability of degradation ondiesel oil, they were Q4, Q10, Q17, Q21and Q25. Strain screening experimentindicated that strain Q21was low temperature degradation bacterium with high oildegradation. After the individual morphological characteristics, physiological andbiochemical identification, whole-cell fatty acid composition analysis and16SrRNAgene sequencing analysis, Q21is identified as Acinetobacter junii.Growth and degradation of performance test of strain Q21showed that thedegradation ability of oil was strongest with10%inoculum concentration in15℃when the pH was7. Under the best degradation conditions, Q21degradation rate was71.50%after27h when the initial concentration of diesel was2000mg/L. Thedegradation rate was still more than30%when the salinity was3%, showing the saltresistance. The optimum salinity was between0.5%~1%, the degradation rate canreach70%.Diesel oil contains all the alkane C9~C24, after strain Q21degradationtreatment, alkane component types decreased significantly in residual oil components,And single alkane content also reduce.Q21has strong degradation ability to C9~C15alkanes. It can degrad most of branched alkanes and some high carbon numberalkanes, having a wide range of degradation. This article provides a theoretical basisin the application of oil degradation bacteria in the traditional biological treatmentand repair system under the low temperature, having a great guiding significance. |
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