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http://hdl.handle.net/1783.1/1624
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| Title: | Microbial desulfurization of dibenzothiophene |
| Authors: | Maxwell, Samiapillai
Yu, Jian |
| Keywords: | Dibenzothiophene
Desulfurization
Biotransformation
Fossil fuels |
| Issue Date: | 1999 |
| Citation: | Proceedings of the Asia-pacific Chemical Reaction Engineering Symposium "APCRE 99", Hong Kong SAR, China, June 13-16, 1999, The Hong Kong University of Science and Technology, Hong Kong SAR, China, 1999, p. 455-460 |
| Abstract: | Combustion of organic sulfur compounds present in fossil fuels releases SO2, a major air pollutant causing acid rains. Dibenzothiophene (DBT) is a representative organic sulfur compound in fossil fuels such as oil and coal. Desulfurization of DBT by the living cells, resting cells and enzymes of a bacterium was investigated in this study. The bacterial strain was isolated from soil by repeated cultivation in a selective medium with DBT as the sole sulfur source. The medium contained sulfur-free mineral salts as the growth nutrients and glycerol and glucose as the carbon and energy source. The strain could grow on DBT, but its maximum growth was found in a medium of DBT plus thiamine (50 mg/L). GC-MS analysis of the medium reveals that the strain transformed DBT to 2-hydroxybiphenyl (2HBP), a desulfurized compound with the intact carbon skeleton of DBT. The biotransformation was via an intermediate of dibenzothiophene sulfone (DBTS). The organic sulfur was utilized for cell reproduction and little sulfur was left as sulfate in the medium solution. DBT desulfurization was associated with cell growth, which was promoted by inorganic sulfate. A high extracellular sulfate concentration (>0.1 mM) repressed the expression of DBT desulfurization enzymes, but below this level the enzymes were expressed very well with a good growth as well as a stoichiometric biotransformation of DBT to 2HBP. Accumulation of 2HBP, the final product of DBT desulfurization, had an inhibitory effect on both cell growth and DBT desulfurization. DBT desulfurization could also be carried out in a crude enzyme solution if a cofactor NADH was supplied. The DBT content in the enzymatic solution was reduced from 2.45 mM to 2.06 mM giving 0.389 mM 2HBP in 45 min. The enzymatic conversion of DBT to 2HBP was almost at a stoichiometric ratio. DBT was also desulfurized by the resting cells of the bacterial strain, but the cofactor NADH was not needed. |
| URI: | http://hdl.handle.net/1783.1/1624 |
| Appears in Collections: | CBME Conference Papers
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| apcre99d.pdf | | 706Kb | Adobe PDF | View/Open |
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