Insights into the Kinetics of the Microbial Degradation of Dibenzothiophene (DBT) by Acidithiobacillus ferrooxidans

Abstract

Dibenzothiophene (DBT) is a major form of organo-sulfur compound chiefly found in coal. Acidithiobacillus ferrooxidans cells played the role of catalyst in degrading DBT to 2-hydroxy biphenyl (2HBP) through the formation of dibenzothiophene-sulfone and releasing the sulfur present in it. Experiments on the biodegradation of DBT by A. ferrooxidans bacterium using 9K medium with DBT at 3 g/L in a 500 mL shake flask scale achieved degradation of DBT up to 95% in 12 days. The A. ferrooxidans cells degrade DBT to 2-hydroxy biphenyl and release the sulfur atom in DBT through the formation of the intermediate dibenzothiophene-sulfone. The formation of 2HBP from microbial degradation of DBT followed the chemical control model of shrinking core reactions model in solid-liquid interactions. The kinetics of the DBT degradation by A. ferrooxidans followed first-order for a low initial concentration of DBT (3 g/L), and the kinetics were shifted to second-order with an increase in DBT concentration to 5 g/L.

Keywords:

• Dibenzothiophene
• acidithiobacillus
• reaction kinetics
• shrinking core model

Acknowledgments

A.S. acknowledges The Department of Biotechnology, Govt. of India for providing postgraduate student fellowship.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by The Science and Technology Department, Bhubaneswar, Govt. of Odisha through a grant to Dr. S.K. Behera [Research Grant Number: ST-SCST-MISC-0061/2018].