Developments in destructive and non-destructive pathways for selective desulfurizations in oil-biorefining processes

Area of Science:

• Biotechnology
• Environmental Science
• Microbiology

Background:

• Biocatalytic desulfurization is a promising, yet non-commercial, technology for removing sulfur from fossil fuels.
• Rhodococcus rhodochrous IGTS8 is a well-studied microorganism for biodesulfurization.
• Understanding metabolic pathways is crucial for optimizing biocatalytic processes.

Purpose of the Study:

• To investigate the biodesulfurization pathways of dibenzothiophene (DBT) using Rhodococcus rhodochrous IGTS8.
• To identify and characterize metabolic intermediates and byproducts.
• To explore the factors influencing the efficiency of biocatalytic desulfurization.

Main Methods:

• Cultivation of Rhodococcus rhodochrous IGTS8 under different growth conditions.
• Analysis of metabolic byproducts from dibenzothiophene (DBT) desulfurization.
• Enzyme assays to investigate specific hydrolase activities.

Main Results:

• Dibenzothiophene (DBT) desulfurization byproducts, including 2'-hydroxybiphenyl (HBP), sulfite, and sulfate, were found to inhibit the process.
• Two distinct metabolic pathways were identified in Rhodococcus rhodochrous IGTS8: one involving sulfinic acid hydrolase and another involving sulfonic acid hydrolase.
• Experiments suggest that sulfonic acid hydrolase is an induced enzyme, activated by benzene sulfonic acid.

Conclusions:

• The inhibitory effects of byproducts necessitate strategies to mitigate their impact on biocatalytic desulfurization efficiency.
• The identification of two distinct metabolic pathways provides insights into the microbial metabolism of DBT.
• The inducible nature of sulfonic acid hydrolase offers a potential target for enhancing biocatalytic desulfurization through enzyme induction.