Ralstonia eutropha as a biocatalyst for desulfurization of dibenzothiophene

Abstract

The potential of Ralstonia eutropha as a biocatalyst for desulfurization of dibenzothiophene (DBT) was studied in growing and resting cell conditions. The results of both conditions showed that sulfur was removed from DBT which accompanied by the formation of 2-hydroxybiphenyl (2-HBP). In growing cell experiments, glucose was used as an energy supplying substrate in initial concentrations of 55 mM (energy-limited) and 111 mM (energy-sufficient). The growing cell behaviors were quantitatively described using the logistic equation and maintenance concept. The results indicated that 2-HBP production was higher for the energy-sufficient cultures, while the values of the specific growth rate and the maintenance coefficient for these media were lower than those of the energy-limited cultures. Additionally, the kinetic studies showed that the half-saturation constant for the energy-limited cultures was 2 times higher than the energy-sufficient ones where the inhibition constant (0.08 mM) and the maximum specific DBT desulfurization rate (0.002 mmol g h) were almost constant. By defining desulfurizing capacity (D ) including both the biomass concentration and time to reach a particular percentage of DBT conversion, the best condition for desulfurizing cell was determined at 23% g L h which corresponded with the resting cells that were harvested at the mid-exponential growth phase.

Water Splitting–Biosynthetic Hybrid System for CO2 Conversion using Nickel Nanoparticles Embedded in N‐Doped Carbon Nanotubes

“…[50,51] The PHB production was determined by ultraviolet spectroscopy (Cintra 303, GBC, Canada). The DCW was calculated with ac orrelation established between the OD 600 and DCW:D CW (g L À1 ) = 0.4695 OD 600 .T he correlation was established following ap revious publication.…”

“…The DCW was calculated with ac orrelation established between the OD 600 and DCW:D CW (g L À1 ) = 0.4695 OD 600 .T he correlation was established following ap revious publication. [50,51] The PHB production was determined by ultraviolet spectroscopy (Cintra 303, GBC, Canada). The bacterial multiplication was estimated by the amount of biomass, and the ability of the hybrid system to utilize electron and electricity was evaluated by the FE and ECE.…”

Metabolic and process engineering for biodesulfurization in Gram-negative bacteria

“…(betaproteobacteria), Desulfobacterium (deltaproteobacteria), able to desulfurize DBT, have been also described and some of them have been used in BDS processes (Table 1) (Papizadeh et al, 2011;Gunam et al, 2013;Liu et al, 2015;Bordoloi et al, 2016;Mohebali and Ball, 2016;Dejaloud et al, 2017;Gunam et al, 2017;Papizadeh et al, 2017). Nevertheless, the genetic characterization of the desulfurization gene clusters in these Gram-negative bacteria is still missing.…”

Elevated c‐di‐GMP levels promote biofilm formation and biodesulfurization capacity of Rhodococcus erythropolis

“…In fact, the specific desulfurization activity attained with the biofilm approach proposed in this study is 84.2 µmol 2HBP /g DCW/h. This is the highest value described in the literature with either Rhodococcus or other bacterial species when performing microbial resting cell cultures in aqueous phase (Maghsoudi et al, 2001;Martin et al, 2005;del Olmo et al, 2005;Rashtchi et al, 2006;Davoodi-Dehaghani et al, 2010;Alves and Paixão, 2014;Martínez et al, 2016;Ismail et al, 2016;Dejaloud et al, 2017). Additional research to confirm increased bioconversion efficiency may be focused on carrying out resting cells assays in a two-phase system where desulfurization activity is higher than in aqueous media (Davoodi-Dehaghani et al, 2010).…”