Study On Screening And Degradation Effect Of Indigenous Petroleum Degradation Bacteria In Liaoning Province

The composition of oil is complex and the pollution range is large,so it still needs to be repaired.The natural degradation process of petroleum is slow,the degradation process of petroleum pollutants can be accelerated by adding exogenous oil-degrading bacteria.Petroleum-degrading bacteria are characterized by many species,wide distribution,rapid reproduction,small individual,large specific surface area and easy variation,therefore,it shows high efficiency and diversity in remediation of oil-contaminated soil.Using petroleum degrading bacteria to remediation of petroleum contaminated soil has the advantages of simple operation,low cost,no secondary pollution,no damage to soil structure,and is suitable for in situ and ectopic remediation.The native oil-degrading bacteria were more suitable than the non-native strains which were artificially constructed and bred in different places when the oil contamination in different area of space is repaired,and the climate in northern China is dry and cold in autumn and winter,the limitation of adding non-native to repair pollution is great,so screening out native microbes to degrade oil could not only reduce the risk of biological invasion,but also make them adapt to the local environment to repair oil pollution faster and better.In respect of the issues above,the native oil-degrading bacteria screened from nature were selected as the research object in this paper,the effect of degradation of petroleum pollution was discussed.The research content mainly includes the following aspects:First of all,petroleum-contaminated soil was collected from different layers of the former refinery in Tai'an County,Anshan,Liaoning Province,eight microbial strains growing with petroleum as the only carbon source were screened out from the soil microbial flora,numbering them as 1#?8#.The ability of 8 strains to degrade petroleum was studied after three acclimations,the results show that the degradation efficiency of petroleum is in the range of 1.57%?30.2%.Two predominant strains 2#and 3# which showed better oil degradation effect were screened from the above 8oil-degrading strains,among them,strain 2# achieved a good degradation effect after6 days of culture,it can also maintain stably its good degradation effect for a period of time;the oil degradation ability of strain 3# was stronger,After 6 days of cultivation,the oil degradation rate reached 30.2%.Physiological and biochemical characteristics and 16 Sr DNA sequences were analyzed and identified,the results showed that strain2# was Bacillus oleronius,strain 3# belongs to Bacillus.Secondly,because the culture time,temperature,p H value,strain dosage,nitrogen source,petroleum concentration and so on are the main factors affecting the degradation effect of petroleum pollutants,the effects of various factors on the degradation of petroleum were systematically studied.The experiment result shows that 2# strain's Optimum degradation conditions as follow:the incubation time was 6days,the inoculation dose was 10%,the temperature of 35 ?,the p H value was 8.0,the concentration of oil is 1500 mg/L,the nitrogen source is ammonium sulfate;3# strain's Optimum degradation conditions as follow:the incubation time was 6 days,the inoculation dose was 1%,the temperature of 35 ?,the p H value was 8.0,the concentration of oil is 1500 mg/L,the nitrogen source is ammonium sulfate,and both strains 2# and 3# could degrade in the temperature range of 5 to 40 ?,it has a wide range of temperature application,The degradation rate of petroleum can reach about15% at 15 ?,these characteristics contribute to its ability to degrade oil in low temperature environment in the north.In addition,the petroleum degrading bacteria 2# and 3# were combined to construct the compound bacteria,and exploring the change of its degradation effect.The optimum compound ratio of compound bacteria was 2:3,the degradation efficiency of petroleum can reach 62.66%,compared with the single strain of oil degradation efficiency,the degradation rate of petroleum by the compound bacteria increased by about 32.46%.The results showed that the degradation effect of the compound strain was better than that of the single strain,this will lay the foundation for the further use of petroleum-degrading bacteria for remediation of oil-contaminated soils.