Isoloating Of Petroleum Degrading Strains And Biodegrading Characteristics In Huabei Oil Field

The oil pollution control is urgent as oil pollution problem becomes more andmore serious. Biological method is proved to be the most economic and effectivemanagement method to repair the oil pollution because it lies on the pollutantdegradation by oil-degradation-bacterial metabolism. Therefore, choose ofmicroorganisms with oil degradation ability becomes a key to oil pollutionbioremediation.Five petroleum degrading bacterial strains were isolated from oil-contaminatedsoils in Huabei oil field, which labeled as z-3, z-6, z-7, z-8and z-b, respectively. Theyhad strong oil degrading activity, and their oil degradation rates were63.8%,34.2%,44.8%,50.5%and42.3%, respectively. Based on the results of physiological andbiochemical characteristics as well as16S rDNA molecular biological analysis, thefive strains were identified. Both z-3and z-8were affiliated to Pseudomonas sp. Inaddition, z-6, z-7and z-b belonged to Rhizobium, Pseudoxanthomonas, andSphingomonas, respectively. Further study on degradation characteristics of these fivestrains was conducted. Specific conclusions as followed:(1) Microbial quantity had positive correlation with oil degradation ability. Inlogarithmic phase of strains, the degradation rate was the highest.(2) Temperature, pH, salinity, nitrogen source and phosphorus sources had animpact on the5strains both in growth and oil degradation. The optimum conditionsfor strain z-3is pH7.0,30℃,0.5%salinity, potassium nitrate as the nitrogen source,potassium dihydrogen phosphate and potassium hydrogen phosphate as thephosphorus source. strain z-6is pH7.0,30℃,0%salinity, ammonium chloride assource of nitrogen, potassium dihydrogen phosphate and potassium hydrogenphosphate as the phosphorus source. strain z-7is pH7.0,30℃,1%salinity, potassiumnitrate as the nitrogen source, potassium dihydrogen phosphate and potassiumhydrogen phosphate as the phosphorus source. strain z-8is pH7.0,30℃,0.5%salinity, sodium nitrate as the nitrogen source, potassium dihydrogen phosphate and potassium hydrogen phosphate as the phosphorus source. strain z-b is pH7.0,35℃,0.5%salinity, ammonium chloride as source of nitrogen, potassium dihydrogenphosphate and potassium hydrogen phosphate as the phosphorus source.(3) Through monitoring the activity of dehydrogenase and catechol2,3-dioxygenase(C23O)in the5strains, it was found that the higher the enzyme activitymanifestation, the better oil degradation ability was. Dehydrogenase and C23O areinducible enzyme and C23O is intracellular enzyme at the same time.(4) Experiments on these5strains were carried out by mixing with the same ratioof each concentration. Different combinations of bacterial groups were built.Meanwhile, oil degradation rates of bacterium groups were monitored. Resultsshowed that the bacterial groups, combining z-6, z-7and z-6, z-7, z-b, had higher oildegradation rates than a single strain and all of their oil degrading rates were over50%. The oil degradation rates of the rest combining bacteria had decreased.