Sulfur Removal from Dibenzothiopheneby Newly Isolated Paenibacillusvalidus Strain PD2 and Process Optimizationin Aqueous and Biphasic (Model-Oil) Systems

Abstract

A b s t r a c t Dibenzothiophene (DBT) is an organic sulfur compound which remains in oil after hydrodesulfurization (HDS) process and can be removed by biodesulfurization (BDS). A new strain of Paenibacillus validus (strain PD2) was isolated from oil contaminated soils that is able to desulfurize DBT. HPLC analysis and Gibb's assay showed that this strain was capable to convert DBT to 2-Hydroxybiphenyl (2-HBP) as final product. The presence of dszC gene confirmed that DBT desulfurization occurred through the 4S pathway. Maximum growth and the highest induction in dsz operon obtained in the presence of dimethyl sulfoxide (DMSO) as sole sulfur source. DBT concentration, temperature and pH were optimized statistically for growing and resting cells by using Response Surface Methodology (RSM). All parameters in growing cells had a significant effect on 2-HBP production during BDS of DBT by P. validus PD2, although in resting cells temperature in range of 20-40°C was not a significant factor. Maximum BDS for growing cells was obtained at 0.41 mM DBT concentration, pH 6.92 and temperature 31.23°C. For resting cells, optimum pH, temperature and DBT concentration were 6.62, 27.73°C and 7.86 mM respectively. The results of this study showed that high concentrations of DBT could be desulfurized by P. validus strain PD2 in model-oil. Thus, the isolated strain could be introduced as a proper candidate for biodesulfurization of organic sulfur in the oil industry. K e y w o r d s: Paenibacillus validus, 2-hydroxybiphenyl (2-HBP), dibenzothiophene (DBT), Response Surface Methodology (RSM)

Microbial Surfactants: The Next Generation Multifunctional Biomolecules for Applications in the Petroleum Industry and Its Associated Environmental Remediation

“…Dibenzothiophene (DBT) represents the model compound of sulphur-containing species of crude oil and fuel [82]. Rhodococcus erythropolis IGTS8 (a model bacterium) catalyzes DBT via what is known as the four-step desulphurization (4S pathway) in defining the BDS process (Figure 2).…”

Biodesulfurization of Petro-diesel by a Novel Hydrocarbon Tolerable Paenibacillus glucanolyticus HN4

“…The changes in pH would affect the enzymes' 3-D and the electrical charge on the substrate, which consequently would retard or inhibit the substrate binding to the sites of enzymes. Thus, inhibits the enzymatic catalytic activities [25]. In addition, the 4S-pathway enzymes are be active at pH around neutrality (pH 6-8) [26].…”

“…In addition, the 4S-pathway enzymes are be active at pH around neutrality (pH 6-8) [26]. Paenibacillus validus (strain PD2) isolated from oil polluted soil for its ability to desulfurize DBT via 4S-pathway producing 2-HBP [25]. Response surface methodology (RSM) based on 3 3 Box Behnken design was employed to optimize DBT-BDS batch process [25], which revealed relatively similar optimum conditions to those of HN4, recording; 0.41 mM DBT, pH 6.92 and 31.23°C.…”

Microbial Surfactants: The Next Generation Multifunctional Biomolecules for Diverse Applications

“…The dibenzothiophene (DBT) represents the model compound of sulphur-containing species of crude oil and fuel [82] Rhodococcus erythropolis IGTS8 (a model bacterium) catalysed DBT via what is known as the 4S pathway in defining the BDS process (Fig. 2).…”