Study On The Screening Of Dibenzothiophene Desulfurizing Bacteria And Biodesulfurization Characteristics

Dibenzothiophene and its derivatives are an important component of high-sulfur crude oil,its presence not only reduces the oil quality,and also increased sulfur dioxide emissions when burned,which will decline environmental quality,and potentially threatened the ecology systems and human health.In this article,DBT has been used as a model compound to study biodesulfurization.A strain AS-21 which is capable of desulfurizing DBT was isolated from the long-term petroleum-contaminated soil,the strain AS-21 was analyzed by16 SrDNA gene sequence,and optimized the culture conditions and desulfurizeation conditions.On this basis,the AS-21 was inoculated into production liquid,investigate the desulfurization effect of AS-21.Finally,using the AS-21 to made resting cells and study the effect of different concentrations of resting cells to the desulfurization.The article obtained two strains of bacteria AS-21 and AS-26 after enrichment culture,screening,separation and purification,after three days of culture,the desulfurization rate were73% and 69%.The AS-21 was identified as gram-negative bacteria and short rod-shaped cells.After DNA extraction and PCR amplification,the strain AS-21 was identified by analyzing16 SrDNA gene sequence.The searches were conducted with BLAST program in the GenBank,which exhibited high levels of 99% similarity with Rhodopseudomonas.After the single-factor experiments,the optimal culture and desulfurization conditions were: the temperature was 30?;initial pH 7.5;carbon source was 10g/L glycerol;nitrogen source was2g/L ammonium chlorid;the initial DBT concentration was 100mg/L.Response surface methodology showed that when temperature was 29.70 ?,initial pH was 7.43,DBT concentration was 105.47mg/L,the desulfurization rate and strain growth is maximum.The experiment of AS-21 desulfurized DBT in production liquid showed that when added a series of nutrients,the desulfurization rate was 18.38%.The growth curve of this strain indicatedthat the strain AS-21 stepped into logarithmic phase after 15 hours which lasted to about 50 hours.Then,the growth of strain AS-21 entered stationary phase.The desulfurization rate of resting cells was 81%,higher than ordinary strains.