Screening, Identification And Degradation Characteristics Of Dibenzothiophene Desulfurizing Bacteria

When it comes to energy, most people may think of different kinds of fossil fuels, such as petroleum, gas and coal. Nowadays, they are the most widely used energy materials in many countries across the world. Especially the development and use of petroleum, making its supply quantity closely linked with the fate of conntry, it is also about the lifeline of one countries’ industrial economy. So it is vividly called “the blood of industry”by people. The formation and structure of fossil fuels are very special and complex, almost all the fossil fuels contain sufler elements,which include inorganic and organic sulfur. Most inorganic sulfur exists in the form of elemental sulfur and pyrite. Organic sulfur mainly includes sulfide, mercaptan, thiophene and other heterocyclic compounds with more complex structure. However, sulfur is pumped out into the atomosphere through various ways, causing severe environment contamination. So how to reduce the emissions of the organic sulfur become one of the most urgent and difficult task for everye country around the world. Meanwhile, dibenzothiophene(DBT) is the major heterocyclic organic sulfur compound in petroleum, which is difficult to remove using the traditional desulfurization technology. Therefore, most of the biological desulfurization technologies usually use DBT as model compounds to do research.The paper maked DBT as the sole source of sulfur to domesticate and isolate a DBT desulfurization strain 5-1 with high activity and degradation specificity of DBT from the soil contaminated by petroleum. The identification result through BIOLOG was corynebacterium and the gram staining was positive.Through the growth curve of strain 5-1, result showed that strain 5-1 began to enter logarithmic phase after 12 h, which probably lasted 40 h. After this, the strain entered the stationary phase, with the same duration of 40 h. Conclusion was drew from the determination of the strain desulphurization curve that the initial concentration of DBT degradated from 0.2mmol/L to 0.0284mmol/L, obtaining a high DBT degradation rate of 85.8%.The paper conducted experiments on the optimization of culture conditions through eight groups of single factor experiments. The best culture conditions for strain 5-1 were listed as follows: sugar as the best carbon source, ammonium chloride as the best nitrogen source, the best C/N ratio was 25:1, the best temperature was 30℃,the best initial p H value was 7.0, the best initial concentration of DBT was 0.2mmol/L, the best inoculation quantity was 1m L and the best table speed was 200r/min.