Production of a Biocatalyst of Pseudomonas putida CECT5279 for Dibenzothiophene (DBT) Biodesulfurization for Different Media Compositions

Abstract

The production of a biocatalyst of a genetically modified microorganism (GMO) (Pseudomonas putida CECT5279) that can desulfurize dibenzothiophene (DBT) has been studied. The biomass growth rate and the development of the sulfur-removal capability during microorganism growth have been measured and modeled. Different growth media and different carbon-glucose, carboncitrate, and carbon-glutamic acid sources, as well as different nitrogen-ammonium and/or nitrogen-glutamic acid sources, have been used, in addition to different glutamic acid concentrations (5, 10, 20, and 40 g/L), to study their influence on the growth rate and desulfurizing capability. Experimental results show clear differences both in growth and in the biodesulfurization capability developed by the cells, depending on the media composition. To quantify the desulfurization capability, a parameter has been defined: D BDS , which is the degree of biodesulfurization developed during growth. This parameter is useful not only to compare the results achieved under different media and conditions but also to compare different microorganisms, in regard to the desulfurization capability. Inside the experimental range studied, the best production media is composed of 20 g/L of glutamic acid, with 670 ppm of NH 4 + as the respective carbon and nitrogen sources. A nonstructured kinetic model that describes the growth and desulfurizing capability development is proposed and applied by nonlinear simple response fitting to all the experiments that have been performed. The model can be used to describe all the experimental data with good statistical parameters.

Description of by-product inhibiton effects on biodesulfurization of dibenzothiophene in biphasic media

“…The basal salt medium (BSM) has been used for the growing steps. This medium has been described previously in literature (H. del Olmo et al 2005a;Martin et al 2004), and it is composed by NaH 2 PO 4 H 2 O 4 g l -1 , K 2 HPO 4 Á 3H 2 O 3 g l -1 , MgCl 2 Á 6 H 2 O 0.0245 g l -1 , CaCl 2 Á 2H 2 O 0.001 g l -1 , FeCl 3 6H 2 O 0.001 g l -1 , glycerol 2 g l -1 .…”

“…2005a; Martin et al 2004). The growth media used with both strains have different carbon and sulfur sources in order to optimize both the final cell concentration and the desulfurization activity.…”

“…Then the media was centrifuged at 7,000 r.p.m., 5 min and 4°C and into NaCl 9 g l -1 re-suspended. A 2 l bioreactor is inoculated with 0.25 g l -1 of inoculum and BSM media, with Lglutamic acid 20 g l -1 , NH 4 Cl 2 g l -1 , MgSO 4 0.44 g l -1 , TC 9.1 mg l -1 and IPTG 43.2 mg l -1 , inductor of 4S pathway enzymes production (Martin et al 2004). Operational conditions were the same as described above.…”

Recent Advances in the Science and Technology of Desulfurization of Diesel Fuel Using Ionic Liquids

“…Additionally, BDS can effectively remove some key sulfur-containing compounds that are among the most difficult for HDS to treat. BDS can be used instead of, or complementary with, HDS [40][41][42][43][44][45][46][47][48][49][50][51][52].…”

Analysis of Dibenzothiophene Desulfurization in a Recombinant Pseudomonas putida Strain

“…Samples collected at different growth times were used for resting-cell desulfurization assays using the substrates for all the 4S route enzymes (DBT, DBTO, DBTO 2 , and HBPS). Cells (0.7 g dry cell weight [DCW]/liter) were suspended in 50 mM HEPES buffer (pH 8.0) and 10 M substrate, and desulfurization was carried out at 30°C for 2 h. Samples (0.25 ml) were collected, and the concentrations of DBT, DBTO, DBTO 2 , HBPS, and HBP were determined by high-performance liquid chromatography as previously described (16,17). The BDS capability (X BDS ) of the cells was determined as the percentage of desulfurization according to the equation X BDS ϭ (C HBP,2 /C DBT,0 ) ϫ 100, where C DBT,0 is the initial concentration of DBT (M) and C HBP,2 is the HBP concentration (M) after a 2-h resting-cell assay.…”