Genetic Analysis of Benzothiophene Biodesulfurization Pathway of Gordonia terrae Strain C-6

Wei Wang,Ting Ma,Huimei Tian,Kehui Lian,Yue Zhang,Kaihua Ji,Guoqiang Li,Inês A Cardoso Pereira

doi:10.1371/journal.pone.0084386

Abstract

Sulfur can be removed from benzothiophene (BT) by some bacteria without breaking carbon-carbon bonds. However, a clear mechanism for BT desulfurization and its genetic components have not been reported in literatures so far. In this study, we used comparative transcriptomics to study differential expression of genes in Gordonia terrae C-6 cultured with BT or sodium sulfate as the sole source of sulfur. We found that 135 genes were up-regulated with BT relative to sodium sulfate as the sole sulfur source. Many of these genes encode flavin-dependent monooxygenases, alkane sulfonate monooxygenases and desulfinase, which perform similar functions to those involved in the 4S pathway of dibenzothiophene (DBT) biodesulfurization. Three of the genes were found to be located in the same operon, designated bdsABC. Cell extracts of pET28a-bdsABC transfected E. coli Rosetta (DE3) converted BT to a phenolic compound, identified as o-hydroxystyrene. These results advance our understanding of enzymes involved in the BT biodesulfurization pathway.

Highlights

Sulfur-oxide gases are released during the combustion of sulfur compounds, which results in serious air pollution, and poison metal catalysts [1]
As DBT is a common organosulfur compound found in a variety of fuels and more resistant to HDS treatment than other thiophene sulfides, it is widely regarded as a model compound for the isolation and characterization of biodesulfurization bacteria [6]
BT utilization, and product yield of strain C-6 cultured with BT as sole source of sulfur

Summary

Introduction

Sulfur-oxide gases (mostly SO2) are released during the combustion of sulfur compounds, which results in serious air pollution, and poison metal catalysts [1]. Benzothiophene (BT), dibenzothiophene (DBT), and their alkylated derivatives, account for more than 50% of the total sulfur content of commercial diesel [2,3]. These aromatic thiophenes are recalcitrant organic sulfur compounds and more resistant to hydrodesulfurization (HDS) treatment than other sulfur compounds such as mercaptans and sulfides [4]. As DBT is a common organosulfur compound found in a variety of fuels and more resistant to HDS treatment than other thiophene sulfides, it is widely regarded as a model compound for the isolation and characterization of biodesulfurization bacteria [6]. Two major pathways of DBT biodesulfurization have been reported and designated the “Kodama” and “4S”

Methods

Results

Conclusion