Isolation, Identification And Oil-degradation Characteristics Of Bacterial Species And Microbial Communities

With the rapid development of oil industry, the activities of oil exploration are increasing, which has induced the result that oil pollution has become a common concern in the countries of the world. There are many obvious advantages on the treatment of crude oil pollution using bio-technology, such as high-speed, low consumption, high efficiency, free of second pollution, environmental friendly and mild conditions etc. So bio-technology offers us the prospect for solving the problem of oil pollution. In this thesis, the bacteria owning the ability of degradating crude oil were isolated from polluted soil, oilwell wastewater and sewage treatment pond wastewater. And then, the study of certain bacteria species identification and oil degradation factors was conducted. Polyurethane foam unit (PFU) was chosen to absorbing the oil-degradation bacteria, and the oil-degradation ability of PFU immobilized bacteria was studied. Also, the oil-degradation ability of natural PFU microbial communities was also included. The main results were as follows:1. The samples from contaminated soil of Renqiu, polluted water of Liuzan Tangshan and sewage treatment pond wastewater of Yanshan Petrochemical company were used to isolate oil degradation microbe. The oil degradation rates of the 42 bacterial strains were tested, TLA-1 showed the highest oil degradation rate (67.14%) among the 42 bacterial strains.2. Morphological observation, physiological and biochemical test, and melocular biology technological 16SrDNA were used to identify the isolated microbes, and 12 stains were identified. TLA-1, which showed the highest degradation rate was identified as Pseudomonas aeruginosa. The best crude oil degradation condition of Pseudomonas aeruginosa was: pH 7.0, initial crude oil concentration 0.5%, and the inoculum size 1.0 mL in the logarithmic phase (about 1.8×1010 cfu/mL).3. The oil degradation rates of Acinetobacter schindleri, Staphylococcus epidermidis, Staphylococcus aureus and Psychrobacter pulmonis were 54.48%, 16.51%, 43.13% and 43.00% respectively, above results were firstly reported in this paper.4. Three sizes (2.0 cm, 1.0 cm and 0.5 cm) of PFUs were used to absorb bacteria, and the oil degradation ability of immobilized bacteria was tested. The result showed that the bacteria absorb by 0.5 cm PFU block had the highest degradation of 64.45%, 41.25% higher than that of the control group .The 2.0 cm and 1.0 cm sizes PFU groups were 20.74% and 22.92% higher than that of the control group. The results showed that the PFU fixing bacteria had better ability to crude oil degradation.5. Narural microbial communities were collected using PFU method, and oil degradation ability of PFU microbial communities were measured. The highest degradation rates of PFU microbial communities for crude oil and 20# heavy diesel were 69.99% and 66.92% respectively, which were similar to degradation rates of the isolated bacterial stains. The result confirmed that the PFU microbial communities have oil biodegradation ability.