Desulfurization of Dibenzothiophene by Pseudomonas fluorescens (UCP 1514) Leading to the Production of Biphenyl

Abstract

Dibenzothiophene (DBT) is a typical recalcitrant thiophenic sulfur component of fuels, and its desulphurization has been a model reaction in the treatment of these compounds. Based on this information, the potential of Pseudomonas fluorescens (UCP 1514) on the desulfurization of dibenzothiphene was studied, in order to use it for reducing the sulfur content of diesel oil in compliance with environmental regulations. The result of biodegradation by the bacteria was determined by undertaking high-performance liquid chromatography of the metabolites produced. These can also be identified by gas chromatography with a mass spectrometry detector, and doing so revealed a sulfur-free product, biphenyl, as the final product of the degradation process. The results showed a decrease of 73% in dibenzothiophene content, which means that P. fluorescens removes sulfur from dibenzothiophene with a good selectivity to form biphenyl. These promising results indicate that P. fluorescens has an interesting potential to degrade sulfur-containing compounds in diesel oil and thereby could help in removing sulfur content from diesel oil. The process of microbial desulfurization described herein can be used particularly after carrying out hydrodesulfurization. Consequently, the sulfur content could be reduced even further. Applying P. fluorescens UCP 1514 in dibenzothiophene could help to understand the nature of the biodegradation process and to achieve the regulatory standards for sulfur level in fossil fuels.

Optimizing the Metabolic Performance of Mixed Bacterial Culture Towards Dibenzothiophene Desulfurization under the Effect of Varying Nutrient and Environmental Factors

“…Naturally, DBT is a xenobiotic compound and at the elevated level, it had a negative effect on cell growth and desulfurization performance of microorganisms. Such kind of effect was also shown by Thayse et al [29] by providing DBT as the bioavailable source of sulfur to Pseudomonas fluorescens UCP 1514. The bacterium exhibited a maximum of 73% desulfurization when supplied 2 mM of DBT, however, the desulfurization achieved with the consortium IQMJ-5 (current paper) is 80%.…”

Bio-catalytic degradation of dibenzothiophene (DBT) in petroleum distillate (diesel) by Pseudomonas spp.

“…DBT metabolites such as DBTO, DBTO 2 and HBPS were not detected in this study. Similarly, Silva et al 34 confirmed in their investigations that intermediate metabolites including DBTO, DBTO 2 , and HPBS were not discovered by GC-MS analysis, which might be explained by the existence of another pathway for the breakdown of DBT. Therefore, further investigations are required to identify all the metabolites in the 4S pathway.…”

“…Other authors also confirmed that other metabolites of the 4S pathway could not be detected in the experiment. However, they are indicated as postulated metabolites [32][33][34] .…”

Assessment of the dibenzothiophene desulfurization potential of indigenously isolated bacterial consortium IQMJ-5: a different approach to safeguard the environment

“…The two most important pathways identi ed in different bacteria for the desulfurization of DBT are the Kodama and the "4S" pathways (Mohebali et al, 2007, Bordoloi et al, 2016. The Kodama pathway is also called a degradative or ring-destructive pathway because in this pathway the bond between two carbon atoms is broken (Silva et al, 2018). The "4S" pathway is also called a sulfur-speci c pathway in the sense, that the sulfur atom in DBT is released as sul te while the carbon skeleton of DBT remains unchanged, and results in retaining the calori c value of fossil fuels.…”