The Optimization Of Culture And Combination Of Oil-degrading Bacteria

As an important energy source,with the development of contemporary industry,the demand of oil is increasing and the scope of application is more and more widely.Various oil spill accidents are becoming more and more serious harm to the natural environment and human beings,which makes the oil pollution control become a global concern.Because of its economic and environmental benefits,it is one of the most effective ways to control the pollution of petroleum hydrocarbon,and it is of great practical significance to study the bioremediation of petroleum hydrocarbons,as compared with traditional repair technology such as physical and chemical remediation.In this paper,three strains of NDL-2,NDL-5 and NZ-4 were selected from the oil-degrading bacteria selected from the laboratory.Morphological observation and 16S rDNA identification of the three strains were carried out.Three strains were identified as Rhizobium,Klebsiella pneumoniae and Bacillus,respectively.The ability of strain NDL-5 to decrease oil was determined by oil plate culture,and the ability of producing surfactant could be determined.The growth and fermentation conditions of the strain were optimized by single factor test.The effects of carbon source,nitrogen source,bacteria concentration,and so on were studied from the growth of strain itself,the ability of strain to produce surfactant and the ability of strain to degrade crude oil.The optimum culture conditions were as follows:soluble starch with 0.5%carbon source and 1.0%corn nitrate,10%in the amount of bacteria,and the incubation time was 10 h,the degradation time was 6 d.The results showed that the optimized ability of NDL-5 strain to degraded crude oil was improved,and the ability of strain to grow and its ability to produce surfactant was positively correlated with the degradation ability of crude oil.After optimization,NDL-5 strain reached a crude oil degradation rate of 42.3%.In order to further study the surfactant produced by NDL-5 strain,the surfactant in the culture medium was extracted and identified.The results showed that the surfactant produced by the strain was a lipopeptide and its emulsification characteristics in the process of degradation of crude oil has an important role in promotion.As a result of the combination of the crude oil components,the single strain can only be used for the degradation of certain components,so this paper continues to study the strain of the degradation of crude oil characteristics,The change of components before and after be degraded in crude oil by three strains were firstly analyzed.Then three kinds of combination were obtained by proportion one to one as NDL-2 and NZ-4,NDL-2 and NDL-5,NZ-4 and NDL-5.And GC-MS were used to analysis the degradation of crude oil after been combinationed.The results showed that the degradation rate of crude oil was greatly improved by the strain,and the degradation rate of components which were not degraded or degraded poor in crude oil can be degraded greately after combinationed.The degradation rate of NDL-2 and NDL-5 was the best,and the average degradation rate of crude oil reached 89.8%.