[Screening, identification of the strain Fds-1 for microbial desulfurization specially and its use in diesel oil desulfurization].

A strain Fds-1, which can specially break the C-S bond of dibenzothiophene (DBT) and convert DBT into 2-hydrobenzophene (2-HBP), was screened out from soil soaked with crude oil and identified as Bacillus subtilis. Both Gibb's reaction and GC-MS analysis proved that this bacterium could remove sulfur of DBT by "4S" pathway. The optimal temperature of desulfurization is 30 degrees C. At this temperature, Fds-1 could remove 0.5mmol/L organ sulfur of DBT in 72h, so it is suitable to decrease the sulfur content of diesel oil. The final product named 2-HBP is a water-soluble compound. This research focused on the desulfurization methods of diesel oil using Fds-1 resting cells. The results showed Fds-1 exhibited strong degradation capacity of DBT and alkyl-DBT in diesel oil. Experiments of two diesel oil samples for desulfurization proved that Fds-1 did not break the carbon-carbon backbone and the calorific value of diesel oil was reserved. Therefore strain Fds-1 is significant to deep biodesulfurisation comparing the hydro-desulfurization of diesel oil.

[The innate ability of Rhodococcus sp. SDUZAWQ to tolerate sulfur in petroleum].

Removal of sulfur from petroleum can be accomplished by various means. One method is to use microorganisms, such as bacteria. In the present study, strain Rhodococcus sp. SDUZAWQ was employed to test the effects of various concentrations of dibenzothiophene (DBT) and sulfate, had on this removal process. Desulfurization was accomplished, using Basal Salts Medium (BSM), supplemented with 0.2mmol/L DBT and different concentrations of Na2SO4. Growth of SDUZAWQ was pronounced, even when the concentration of DBT was increased to 6mmol/L. Furthermore, it should be noted that the end product of DBT desulfurization, 2 hydroxybiphenyl (2-HBP), was detected as well. This finding was significant because it demonstrated the bacteria' s ability to withstand high concentrations of organosulfur. Dibenzothiophene was utilized when both DBT and Na2SO4 were present in the culture medium. Additionally, 2-HBP was produced. These data are in contrast to previous studies that indicated that DBT could not be metabolized by Rhodococcus sp. in the presence of sulfate. Finally, cloning and sequencing of the gene cluster dszABC, its upstream regulatory sequence and dszD, demonstrated that they share 99%, 100% and 100% with those of R. erythropolis IGTS8, respectively.

[Selectively desulfurizing organic sulfur of diesel oil by resting cells].

Rhodococcus sp. FS-1 ,which can specially break the C[single bond]S bond of dibenzothiophene (DBT) and convert DBT into 2-hydrobenzophene by "4S" pathway, is used to decrease the sulfur content in diesel oil. This research focuses on the diesel oil desulfurization using resting cells of Rhodococcus sp. FS-1. The research result indicate that the desulfurization activity of the resting cells of Rhodococcus sp. FS-1 was strongly high. When the concentration of DBT was 0.5 - 1.0mmol/L and the ratio of oil/water was 1:5, the effect of desulfurization was highest. The desulfurization rate was over 85 % when desulfurizing the diesel oil twice. GC analysis proves that this process did not break the carbon-carbon backbone. The calorific value of diesel oil is reserved.