Screening Of Crude Oil Degrading Bacteria And Basic Research On Its Application

With the increase of social demand for oil,oil pollution to the environment occurs from time to time,which destroys the ecological environment and indirectly threatens human health.Crude oil compounds,including polycyclic aromatic hydrocarbons(PAHs),pose significant environmental damages due to their wide distribution,persistence,high toxicity,mutagenicity,and carcinogenicity.There is significant interest in studying microorganisms present in contaminated environments for use in bioremediation.The use of bioremediation technology to eliminate PAHs from the environment is suggested to be an efficient,economical and versatile alternative to physicochemical treatments.This paper elaborates on the pollution hazards of petroleum,main treatment technologies,types of crude oil degrading bacteria,environmental factors and functional genes related to the degradation of petroleum,focusing on the degradation characteristics of crude oil degrading microorganisms and its influencing factors.The purpose of this study is to screen out high-efficiency crude oil-degrading bacteria,provide strain resources for microbial remediation of oil-contaminated environment,and provide theoretical basis for the repair of crude oil-contaminated environment by the related research on strain degradation characteristics and degradation conditions.as follows:(1)In this study,18 strains of oil-degrading bacteria were screened from petroleum wastewater and sludge samples collected from Changqing Oilfield.The strain Acinetobacter sp.HX09 had the highest degradation efficiency,and the degradation rate of total crude oil was as high as 64% on 8 days.The degradation rate of strain Enterobacter sp.HX06 was second only to strain HX09,and the degradation rate was 58%.The total crude oil material degradation rate of the remaining strains was 11%-53%.(2)The optimal conditions for crude oil degradation of two high-efficiency strains were: strain Acinetobacter sp.HX09: p H=7,temperature 30°C,inoculum 2%,oil content 1.5%;strain Enterobacter sp.HX06: p H=7,temperature 30°C The inoculum size is 3% and the oil content is 1.5%.(3)GC-MS analysis of the degradation characteristics of different components of crude oil by strain Acinetobacter sp.HX09 and strain Enterobacter sp.HX06.The results showed that the crude oil degrading bacteria had different degrees of degradation of the total crude oil.The degradation rate of the strain HX09 was 74% except for the medium chain C15 alkane,and the alkanes degradation rate of the medium chain C11-C28 was higher than 85%.The degradation rate of chain C35-C44 alkane was more than 70%;and the degradation rate of Enterobacter sp.HX06 to C12-C27 was relatively low,57%-88%.The degradation rates of the strain Enterobacter sp.HX06 on short-chain alkanes C10,C11 and long-chain alkanes C28-C44 were 70%,79% and 42%-52%,respectively.(4)Using PCR technology to detect the crude oil degradation functional genes in 18 strains,14 strains contained alk B gene,3 strains contained C23 O gene,4 strains contained alm A gene,and 7 strains contained P450.The gene,5 strains contained the nod B gene,indicating that the alk B gene is the most important crude oil degradation functional gene in the crude oil degradation strain obtained by this screening.(5)Differential expression analysis of alk B gene during degradation of high-efficiency crude oil degradation strain Acinetobacter sp.HX09 by fluorescence quantitative PCR.Acinetobacter sp.HX09 strain was cultured with different carbon sources(glucose,C12,C14,C16,C18,C22,C24,C28,C32,C36)as the sole carbon source.The results showed that the expression of alk B was upregulated in the HX09 strain when grown with various alkanes as substrates.Among them,when induced by C16-C32 as substrate,the expression of alk B gene reached the highest at 5 h;when induced with C12 and C14 as substrate,the alk B gene expression was highest at 8 h.The alk B gene in Acinetobacter sp.HX09 strain mainly played a major role in the degradation of C16,C18,C22,C24,C28,and C32 alkanes between 2 h and 5 h,and mainly played a role in C12 and C14 at 5 h-8 h.And 8 h-11 h mainly acts on C36.