Chemistry: molecular biology and microbiology – Micro-organism – per se ; compositions thereof; proces of... – Fungi
Reexamination Certificate
1998-02-26
2001-05-22
Achutamurthy, Ponnathapu (Department: 1652)
Chemistry: molecular biology and microbiology
Micro-organism, per se ; compositions thereof; proces of...
Fungi
C435S189000, C435S252300, C435S262000, C435S282000, C435S320100, C536S023100, C536S023200
Reexamination Certificate
active
06235519
ABSTRACT:
BACKGROUND OF THE INVENTION
Organic sulfur in fossil fuels causes environmental pollution when combusted and sulfur in petroleum can affect the performance of the refining equipment. High levels of sulfur in gasoline can also deactivate catalyst-based engine exhaust emission control systems (Gonzalez, R. G., Hart's Fuel Technology and Management, November/December 1996, 56-61). Therefore, low sulfur level gasoline is required by government regulation and desired by the refinery and auto industry.
Many biocatalysts and processes have been developed to desulfurize fossil fuels, including those described in U.S. Pat. Nos. 5,356,801, 5,358,870, 5,358,813, 5,198,341, 5,132,219, 5,344,778, 5,104,801 and 5,002,888, incorporated herein by reference. Analyses indicate that a limitation in the commercialization of the technology is the ability of the biocatalysts, such as the bacteria and enzymes that are involved in the desulfurization process, to catabolize or metabolize only specific types of organosulfur compounds. These organosulfur compounds, contain aromatic rings, such as, for example, dibenzothiophene (DBT). Often, other organosulfur compounds, such as thiophene, 2, 2′-bithiophene, 2-methylthiophene and 3-methylthiophene, remain in the refined fossil fuel without significant removal by the biocatalyst.
The most common method for petroleum desulfurization is hydrotreating. However, with increasingly stringent regulations this is becoming more difficult and expensive. Conventional hydrotreating can decrease the sulfur level in FCC gasoline from 1000-2000 parts per million (ppm) to 200 ppm for a relatively low cost. However, it is very expensive to produce FCC gasoline below the 200 ppm specification because the light fraction of the FCC gasoline must also be hydrotreated. Due to the high olefin content of the light fraction, the hydrotreating process involves much higher hydrogen consumption and octane loss due to the saturation of olefins (Gonzalez, R. G. (1996), supra).
Over 90% of the sulfur in gasoline resulting from fluid catalytic cracking occurs in thiophene and substituted thiophenes. Thus, to obtain gasoline meeting current requirements for low sulfur content, methods are needed for removing a substantial amount of the thiophene and substituted thiophenes present in gasoline. Therefore, a need exists for efficient and economical methods for removing thiophene and substituted thiophenes from gasoline.
SUMMARY OF THE INVENTION
The present invention relates to the cloning and characterization of genes from
Nocardia asteroides
strain KGB1 which encode one or more enzymes which catalyze the biotransformation of thiophene and substituted thiophenes.
In one embodiment, the invention includes an isolated nucleic acid molecule, such as a DNA or RNA nucleotide sequence or molecule, which encodes one or more enzymes which catalyze one or more steps in the desulfurization of thiophene. Suitable nucleotide sequences can be isolated from, for example,
Nocardia asteroides
strain KGB1.
The present invention also provides a recombinant non-human organism which contains a heterologous nucleic acid molecule comprising a nucleotide sequence encoding one or more enzymes which catalyze the desulfurization of thiophene. In one embodiment, the nucleotide sequence which encodes the desulfurization enzyme(s) is derived from a Nocardia organism, such as
Nocardia asteroides
strain KGB1.
In a further embodiment, the invention provides a method of desulfurizing a fossil fuel, which comprises thiophene or a substituted thiophene. The method includes the steps of (1) contacting the fossil fuel with an aqueous phase containing a recombinant biocatalyst which contains a heterologous nucleic acid molecule comprising a nucleotide sequence encoding one or more enzymes which catalyze the desulfurization of thiophene, thereby forming a fossil fuel and aqueous phase mixture; (2) maintaining the mixture under conditions sufficient for biocatalysis, thereby resulting in a fossil fuel having a reduced thiophenic sulfur content; and (3) separating the fossil fuel having a reduced thiophenic sulfur content from the resulting aqueous phase.
REFERENCES:
patent: 5002888 (1991-03-01), Kilbane, II
patent: 5104801 (1992-04-01), Kilbane, II
patent: 5132219 (1992-07-01), Kilbane, II
patent: 5198341 (1993-03-01), Kilbane, II
patent: 5297625 (1994-03-01), Premuzic et al.
patent: 5344778 (1994-09-01), Kilbane, II
patent: 5356801 (1994-10-01), Rambosek et al.
patent: 5356813 (1994-10-01), Monticello
patent: 5358870 (1994-10-01), Monticello et al.
patent: WO 92/19700 (1992-11-01), None
Snell, E.E., “Tryptophanase: Structure, Catalytic Activities, and Mechanism of Action,”Adv. Enzymol.42:287-333 (1976).
Bibb, M.J., et al., “The Relationship between base composition and codon usage in bacterial genes and its use for the simple and reliable identification of protein-coding sequences,”Gene30:157-166 (1984).
Overby, L.H., et al., “Characterization of Flavin-Containing Monoxygenase 5 (FMO5) Cloned from Human and Guinea Pig: Evidence That the Unique Catalytic Properties of FMO5 Are Not Confined to the Rabbit Orthology,”Arch. Biochem. Biophys.317:275-284 (1995).
Chang, J H, et al., “Desulfurization of Diesel Oils by a Newly Isolated Dibenzothiophene-Degrading Nocardia sp. Strain CYKS2,”Biotechnology Progress14:851-855 (1998).
Atta-Asafo-Adjei, E., et al., “Dimethylaniline Monooxygenase (N-oxide Forming) 5 (EC 1.14.13.8) (Hepatic Flavin-containing Monooxygenase 5) (FMO 5) (Dimethylaniline Oxidase 5) (FMO 1C1) (FMO Form 3),”J. Biol. Chem.268:9681-9689 (1993). Abstract.
Childs John D.
Squires Charles H.
Wang Yongzhao
Achutamurthy Ponnathapu
Energy BioSystems Corporation
Hamilton, Brook, Smith and Reynolds, P.C.
Stole Einar
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