Desulfurization of Dibenzothiophene, Benzothiophene, and Other Thiophene Analogs by a Newly Isolated Bacterium, <I>Gordonia alkanivorans</I> Strain 1B

Abstract

A novel bacterium, Gordonia alkanivorans strain 1B, was isolated from hydrocarbon-contaminated soil. Assessment of the biodegradation of distinct organic sulfur-compounds, such as dibenzothiophene (DBT), benzothiophene (BT), DBT sulfone, and alkylated tiophenic compounds, as the sole source of sulfur was investigated. G. alkanivorans strain 1B was able to remove selectively the sulfur from DBT while keeping intact the remaining carbon-carbon structure. Orthophenyl phenol (2-hydroxybiphenyl) was the only detected metabolic product. The bacterial desulfurization activity was repressed by sulfate. G. alkanivorans strain 1B consumed 310 microM DBT after 120 h of cultivation, corresponding to a specific desulfurization rate of 1.03 micromol/(g of dry cells x h). When an equimolar mixture of DBT/BT was used as a source of sulfur in the growth medium, G. alkanivorans strain 1B assimilated both compounds in a sequential manner, with BT as the preferred source of sulfur. Only when BT concentration was decreased to a very low level was DBT utilized as the source of sulfur for bacterial growth. The specific desulfurization overall rates of BT and DBT obtained were 0.954 and 0.813 micromol/(g of dry cells x h), respectively. The newly isolated G. alkanivorans strain 1B has good potential for application in the biodesulfurization of fossil fuels.