Isolation Of Low-temperature Marine Oil Degrading Bacteria And Their Mechanisms Of Biodegradation

The exploitation, transportion and application of oil in environmental has caused seriouspollution, however, the oil pollution on the sea is particularly serious, especially in the pastfew years, frequent tanker accidents, oil spills and oil drilling are occurred thick and fast. As aresult, oil pollution has been a very serious problem and need to be solved. It remains below15℃for about five months of the year at our country’s northern region, particularly in thenorthern Yellow Sea and Bohai Sea, but mid-temperature microorganism which metabolicactivity are slow, can not be used to environment remediation.This thesis aimed at screening cold-adapted hydrocarbon-degrading bacteria which wereobtained from Arctic seawaters and sediments. It will play a fundamental role used forbioremediation technique and method of eliminating sea oil pollution at low temperature. Inthis paper, firstly, we tested degradation efficiency of the petroleum hydrocarbon-degradingcold-adapted bacteria which were isolated from Arctic sediments. Secondly, morphologicaltests, biochemical reactions and molecular identification of16S rRNA were carried to identifyArctic cold-adapted degrading bacteria, a phylogenetic tree was constructed on the basis ofthe results. Thirdly, we studied the optimization of nutrition and growing condition of theseArctic cold-adapted degrading bacteria. Meanwhile GC-MS spectrogram was used to studytheir degrading characteristics. Finally, petrol, machine oil, fuel oil and crude oil which arecommon oil spilled on the sea were chosed as only carbon source to study the oil degradationcapability of the three bacteria and mixed flora. The results were summarized as follows:Results of identification revealed that they all belonged to the described genusPseudoalteromonas. The optimum degradation temperature of BJ1, BJ9, BJ19and their mixedflora were:15℃,15℃,20℃,15℃; the optimum pH values of them were:7~8; the optimuminitial oil concentration of them were2.5g/L,2.5g/L,10g/L,10g/L; the optimum salinity ofthem were3.5%~7.0%; the optimal initial concentration of nitrogen source of them were:3g/L,4g/L,3g/L,4g/L; the optimal initial phosphorus source concentrations of them were:3g/L,2g/L,2g/L,2g/L. In conclusion, the degraded ratio of mixed flora was larger than onebacteria, meanwhile, mixed flora can live better than one bacteria in dreadful conditions.The degradation rates of these bacteria and their mixed flora were compared after30days. Theresults also showed that the degradation of alkane of BJ1, BJ9, BJ19and their mixed flora werebetter than the effect of PAHs, their degradation rates of alkane were68.01%,67.93%,59.52%and73.21%respectively. Their degradation rates of PAHs were33.04%,20.44%,16.99%and13.21%respectively. But the PAHs degradation rates of their mixed flora is worse than asingle one’s, BJ1has a good result both on the degradation of alkanes and PAHs. Petrol,machine oil, fuel oil and crude oil were chosed which are common oil pollution spilled on thesea as only carbon source, the results indicated that they can degraded petrol and oil obviously,but used the fuel oil and crude oil less.The study of degradation characteristics of Arcticcold-adapted degrading bacteria at low temperature provided efficient bioremediationtechnique and method of eliminating sea oil pollution at low temperature.