Paraffin Removal Capacity And Alkene Metabolism Of Alcanivorax Dieselolei

Paraffin wax is a mixture of alkene and the length of the carbon chain is between 16 to 30.The wax content of petroleum in oilfields is high,averaging over 20%.Paraffin precipitates out and accumulates on the pipeline due to the change of air pressure and temperature in the process of crude oil extraction,which caused a very serious phenomenon of pipeline blockage,thus affecting oil production.Therefore,it is necessary to take measures to remove and control wax.Generally speaking,physical method uses hot washing to clean wells and chemical method uses chemical paraffin remover to remove and control wax.Hot washing can cause formation clay expansion and blockage of oil pipeline,while long-term hot oil cleaning will cause damage to the structure of oil wells;chemical paraffin remover will not only destroy oil well pipeline,but also reduce crude oil quality and damage the environment.These methods are heavy workload,high cost and obvious shortcomings.Therefore,more and more attention has been paid to the environment-friendly,simple and inexpensive microbial methods.Recently,Alcanivorax dieselolei SH02,a paraffin-degrading strain,was isolated from Qinghai Oilfield by our laboratory,and some preliminary identification was carried out.In this paper,paraffin wax was used as the sole carbon source to perform wax removal experiments,and the paraffin removal conditions were optimized.In addition,the alkane-degrading strains were screened from the strains preserved in the laboratory.The paraffin removal rate(Pr)was determined by co-culture of screened strains with A.dieselolei.The degradation process of paraffin by A.dieselolei was analyzed by metabolomics based on UPLC/Q-TOF MS.The composition of the fermentation broth was analyzed,and the degradation mechanism of paraffin by A.dieselolei was preliminarily explored based on the identification results of intracellular and extracellular metabolites.The main research conclusions include the following aspects:(1)In the pure cultivation condition of A.dieselolei SH02,when initial pH value was 7.0 and NaCl concentration was 20 g/L,the effect on Pr was the best(reached 18.45%).Addition of surfactants and increasing inoculation amount would not significantly affect the effect of paraffin removal.Addition of tryptone could reduce the Pr.Addition of liquid paraffin could significantly improve the effect on Pr(reached 82.33%),but the main effect is that liquid paraffin promotes the dissolution of paraffin wax.(2)6 strains of alkane-degradation strains in our laboratory preserved strains were screened,including Pseudomonas aeruginosa,two strains of Microbacillus sp.,Bacillus licheniformis,Bacillus subtilis and one unidentified actinomycete.The Pr of pure culture and co-culture with A.dieselolei were determined.The best combination of Pr was co-culture between B.subtilis and A.dieselolei.However,compared with the Pr of pure culture of A.dieselolei,the enhancement effect was not significant.(3)A total of 88 metabolites including carboxylic acid,cyclic compound,carbohydrate,alcohol compound,aldehyde compound and ketone compound are identified in fermentation broth for paraffin degradation by A.dieselolei,in which 2-oxadipate accumulated over time in the fermentation broth.The intracellular components were basically the same as the fermentation broth.(4)Based on the identification results of intracellular and extracellular metabolites,the carbon chain of the identified straight-chain fatty acids was sequenced,and the pathway of alkane degradation was analyzed.It is found that the degradation of alkanes by the bacterial strain SH02 was a process of multiple oxidation modes,such as ?-oxidation,?-oxidation and so on.