Kinetic Analysis of Microbial Desulfurization of Model and Light Gas Oils Containing Multiple Alkyl Dibenzothiophenes

Kobayashi, Morio; Horiuchi, Keizo; Yoshikawa, Osamu; Hirasawa, Kazuaki; Ishii, Yoshitaka; Fujino, Kazuhito; Sugiyama, Hiroshi; Maruhashi, Kenji

doi:10.1271/bbb.65.298

Cited by 76 publications

(35 citation statements)

References 13 publications

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“…The desulfurization activities of the cells with desulfurizing ability then decreased due to the increase in the molecular weight of the Cx-DBTs as substrates. These observations have been reported previously (Folsom et al, 1999;Kobayashi et al, 2001;Okada et al, 2002a).…”

Section: Comparison Of Desulfurization Activities In Oil/water Two-phsupporting

confidence: 91%

“…Cx-DBTs of more than C4-DBT are believed undergo a BDS process, because they remain in diesel oil treated using the current BDS technology (Folsom et al, 1999;Kobayashi et al, 2001). In this study, it was found that the decrease in V max and increase in K m dependent on the increase in molecular weight of the substrate caused the low desulfurization activity.…”

Section: Correlation Of Log K and Kinetic Parametersmentioning

confidence: 66%

“…Desulfurization studies were usually performed using authentic Cx-DBTs as models. It was observed that activity in the oil/water two-phase reaction system decreased markedly with an increase in the molecular weight of Cx-DBTs as substrate due to the side chain (Folsom et al, 1999;Kobayashi et al, 2001;Okada et al, 2002a). In the water-phase reaction system, this tendency was not observed (Okada et al, 2002a).…”

Section: Introductionmentioning

confidence: 99%

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Analyses of microbial desulfurization reaction of alkylated dibenzothiophenes dissolved in oil phase

Okada

Nomura

Nakahara

et al. 2003

Biotech & Bioengineering

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The kinetics of the oil/water two-phase reaction system was analyzed, and the reaction was carried out with the desulfurization of alkylated dibenzothiophenes (Cx-DBTs) using the desulfurizing microorganism Mycobacterium sp. G3. In the water-phase reaction system, the desulfurization activities were constant with respect to species of Cx-DBTs as substrates. However, the desulfurization activities in the oil/water two-phase reaction system against DBT, 4,6-dimethyl DBT, 4,6-diethyl DBT, 4,6-dipropyl DBT, and 4,6-dibutyl DBT were 49.0, 45.9, 11.5, 1.35, and 0.00 micromol g DCW(-1) h(-1), respectively. The kinetic parameters for the degradation of DBT, 4,6-dimethyl DBT, and 4,6-diethyl DBT were also obtained (V(max) values 90.0, 68.7, and 22.7 micromol g DCW(-1) h(-1) and K(m) values 0.21, 0.70, and 3.03 mM, respectively). The reason for the decrease in activity against Cx-DBTs of high molecular weight was a decrease in the V(max) value and an increase in the K(m) value, the latter being a particularly serious problem. Furthermore, the hydrophobicity of the substrate was evaluated as the capacity factor measured by high-performance liquid chromatography (HPLC). The correlation between substrate hydrophobicity and desulfurization activity indicated that the desulfurization reaction in the oil/water two-phase reaction system is greatly influenced by the hydrophobicity of the substrates. In addition, the influence of the solvent on desulfurization activity was examined, and it was found that not only the hydrophobicity of substrates, but also that of solvents, affected the desulfurization reaction.

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Section: Comparison Of Desulfurization Activities In Oil/water Two-phsupporting

confidence: 91%

Section: Correlation Of Log K and Kinetic Parametersmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

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Analyses of microbial desulfurization reaction of alkylated dibenzothiophenes dissolved in oil phase

Okada

Nomura

Nakahara

et al. 2003

Biotech & Bioengineering

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“…Alcohol proportions were always lower than 1% v/v, avoiding possible toxic effects reported previously (Kobayashi et al 2001;Yan et al 2000). Moreover, in biphasic reaction media the organic solvent used was hexadecane, because its high presence in diesel oil fraction (Maghsoudi et al 2001).…”

Section: Analysis Of 4s-pathway Compoundsmentioning

confidence: 97%

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

et al. 2007

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As several authors have reported previously, the Biodesulfurization of hydrodesulfurization recalcitrants, such as dibenzothiophene, is not yet commercially viable because mass transfer limitations and feedback inhibition effects are produced during the conversion. This work has been focused to investigate the inhibition process in aqueous and oil-water systems with two different aerobic biocatalysts types, Rhodococcus erythropolis IGTS8 and Pseudomonas putida CECT 5279. The results obtained have proven that global DBT desulfurization process using CECT 5279 was not clearly deactivated due to final product accumulation, under the experimental conditions assayed. Consistently, the desulfurization pattern has been described with the Michaelis-Menten equation, determining the kinetic parameters. On other hand, the assays have shown that important mass transfer limitations produced the decrease of the yields obtained with this Gram(-) strain in biphasic media. With strain IGTS8 it was observed lower mass transfer problems, but contrary the reaction was severely affected by the final product accumulation, in both aqueous and biphasic systems. Therefore it has been proposed an enzymatic kinetic model with competitive inhibition to describe the BDS evolution pattern when this Gram(+) strain was used.

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“…Accordingly, to date, most BDS studies have focused on DBT and alkylated derivatives (9,17,18), but the need to achieve extremely low levels of sulfur in diesel and in other oil streams such as gasoline has demanded a broader substrate range than the Dsz system can provide. Certain petroleum streams contain, in addition to alkylated DBTs, a variety of alkyl and aryl sulfides, thiophenes, and benzothiophenes (6,19).…”

mentioning

confidence: 99%

Chemostat Approach for the Directed Evolution of Biodesulfurization Gain-of-Function Mutants

Arensdorf¹,

Loomis²,

DiGrazia³

et al. 2002

Appl Environ Microbiol

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Chemostat enrichment is a classical microbiological method that is well suited for use in directed-evolution strategies. We used a two-phase sulfur-limited chemostat to select for gain-of-function mutants with mutations in the biodesulfurization (Dsz) system of Rhodococcus erythropolis IGTS8, enriching for growth in the presence of organosulfur compounds that could not support growth of the wild-type strain. Mutations arose that allowed growth with octyl sulfide and 5-methylbenzothiophene as sole sulfur sources. An isolate from the evolved chemostat population was genetically characterized and found to contain mutations in two genes, dszA and dszC. A transversion (G to T) in dszC codon 261 resulted in a V261F mutation that was determined to be responsible for the 5-methylbenzothiophene gain-of-function phenotype. By using a modified RACHITT (random chimeragenesis on transient templates) method, mutant DszC proteins containing all possible amino acids at that position were generated, and this mutant set was assayed for the ability to metabolize 5-methylbenzothiophene, alkyl thiophenes, and dibenzothiophene. No mutant with further improvements in these catalytic activities was identified, but several clones lost all activity, confirming the importance of codon 261 for enzyme activity.

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Kinetic Analysis of Microbial Desulfurization of Model and Light Gas Oils Containing Multiple Alkyl Dibenzothiophenes

Cited by 76 publications

References 13 publications

Analyses of microbial desulfurization reaction of alkylated dibenzothiophenes dissolved in oil phase

Analyses of microbial desulfurization reaction of alkylated dibenzothiophenes dissolved in oil phase

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

Chemostat Approach for the Directed Evolution of Biodesulfurization Gain-of-Function Mutants

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