Screening And Degradation Characteristics Of Petroleum Hydrocarbon Degrading Bacteria

The great harm caused by the:petro leum hydrocarbon in oil spill to human health,ecological environment and social economy has attracted more and more attention.In this paper,aiming at the goal of oil spill bioremediation,the petroleum hydrocarbon degrading bacteria were screened from seawater to contribute to the oil spill pollution restoration.The main research results are as follows:(1)Two strains of petroleum hydrocarbon degrading bacteria HSJ-1 and HSJ-2 were screened from seawater using the method of streak plate.Both strains were identified by 16S rRNA sequencing as Cobetia sp.which could produce surfactants,and the sequence similarity was up to 100%and 99.3%,respectively.(2)The single variable method was used to study the effects of pH,temperature,salinity and carbon-to-nitrogen ratio on the activities of HSJ-1 and HSJ-2.The results showed that the optimal pH of HSJ-1 and HSJ-2 was 8.0 and 7.5,the optimal temperature,The salinity and carbon-to-nitrogen ratio are the same,respectively 25?,4.5%and 32:1.Both strains are typical marine bacteria,have good adaptability to alkaline environment and high salinity environment,and can adapt to the seasonal change of seawater temperature with a wide range of temperature adaptation.(3)Under the optimal growth conditions of HSJ-1,the degradation characteristics of petroleum hydrocarbons were investigated.During the experiment,the saturated hydrocarbons and polycyclic aromatic hydrocarbons were separated by silica gel-alumina column,and the saturated hydrocarbon components were obtained by urea complexation.The contents of each component were measured by GC-MS.The results shows that after 15 days of degradation experiments,the average degradation rates of n-alkanes in 0#diesel and crude oil by HSJ-1 reached 71.19%and 64.58%,and the average degradation rates of polycyclic aromatic hydrocarbons reached 64.09%and 60.60%,n-C10,n-C11,naphthalene and phenanthrene were completely degraded.HSJ-1 has good degradation ability for n-alkanes and polycyclic aromatic hydrocarbons,and its degradation rule follows the priority of degradation of hydrocarbons with low carbon number and simple structure,and then degradation of hydrocarbons with high carbon number and complex structure,and the degradability of light oil(0#diesel oil)is higher than that of heavy oil(crude oil).(4)HSJ-1 was used for the degradation experiment of 0#diesel oil and crude oil in natural seawater,with the purpose of exploring its application in oil spill recovery.The results showed that the average degradation rates of n-alkane and PAHs in 0#diesel oil were 58.87%and 51.59%,and that of n-alkane and PAHs in crude oil were 47.99%and 43%respectively.HSJ-1 has a certain degradation rate of 0#diesel oil and crude oil in natural seawater.Although the degradation rate of HSJ-1 is not as high as that of the optimal growth condition,it still has the potential to be applied in the oil spill recovery project,which is of positive significance to the oil spill recovery.In this paper,strains HSJ-1 and HSJ-2 with unclear ability of degrading petroleum hydrocarbons were screened out,and the ability of degrading petroleum hydrocarbons of HSJ-1 was investigated.It was found that HSJ-1 had good ability of degrading petroleum hydrocarbons in spilled oil and played an important role in oil spill recovery.