Study On The Screening And Degradation Characteristics Of Highly Efficient Crude Degrading Bacteria

In recent years, along with the economic development, oil demand is growing, resulting in the increasing of oil extraction wastewater’s emissions increases. But the treatment success rate is very low, and how to control the problem of environmental pollution caused by petroleum use and oil exploitation has become the concerned focus in the world. Currently, the pysical and chemical treatment of oil production wastewater are considered to be a process of complex operation and low input-output ratio, and can easily cause secondary pollution. Microbial degradation has no additional chemical reagents in the process of operation and low energy consumption, and will not cause secondary pollution. So it has become the focus of the domestic and foreign experimental research.In order to investigate microbial remediation of oil extraction wastewater, this study aim to isolate microbial degradation strains that have good repair effect, and determine their growing conditions and degradation performance.In the present study, four microbial degradation strains were obtained and named3#,2#,10#, and6#. The main findings are as follows:1.4strains degradation bacterias were isolated from Jilin oil field long-term polluted by oil, and all four types of bacteria have the ability to degrade crude oil.2. The results of16S rRNA amplification, sequencing, and homology analysis shown that bacterium3#belongs to Pseudomonas sp., bacterium2#belongs to Agrobacterium sp., bacterium10#belongs to Rhodococcus sp., bacterium6#belongs to Gordonia sp..3. The optimum growing conditions of four bacteria are as follows:degradation strain3#: crude oil concentration6.0g/L, pH=7.0, salt concentration8%, T=35℃.2#:crude oil concentration10.0g/L, pH=7.0, salt concentration8%, T=35℃.10#:crude oil concentration8.0g/L, pH=7.0, salt concentration4%, T=35℃.6#:crude oil concentration10.0g/L, pH=8.0, salt concentration4%, T=35℃.4. The growth and degradation rate of four degradation strains in their respective optimum growth conditions are increased. Degradation rate are61.63%,53.83%,49.24%and45.97%, respectively.5. All four degrading strains have good ability to use hydrophilic carbon source (beef extract peptone medium), OD600value is reached above0.5that is a lot higher than the original 6. Mixed bacteria C (bacteria3#and bacteria2#) has higher degradation rate under different circumstances, max value is69.40%, as advantage mixed bacteria.