Edwin S. Olson

Bio: Edwin S. Olson is an academic researcher from University of North Dakota. The author has contributed to research in topics: Mercury (element) & Flue gas. The author has an hindex of 22, co-authored 66 publications receiving 2985 citations.

Microbial desulfurization of dibenzothiophene: A sulfur‐specific pathway

Abstract: Rhodococcus rhodochrous strain IGTS8 metabolizes dibenzothiophene, a model compound for organic sulfur in fossil fuels, in a sulfur-specific manner. Two routes of desulfurization have been identified. Under growth conditions, the intermediates are dibenzothiophene sulfoxide, dibenzothiophene sulfone, 2′-hydroxybiphenyl-2-sulfonate, and 2,2′-dihydroxybiphenyl. Stationary phase cells produce 2-hydroxybiphenyl as the desulfurized product and use the 2′-hydroxybiphenyl-2-sulfonate, rather than the sulfonate, as key intermediate.

Elucidation of the metabolic pathway for dibenzothiophene desulphurization by Rhodococcus sp. strain IGTS8 (ATCC 53968)

Abstract: Summary: Rhodococcus sp. strain IGTS8 (ATCC 53968) is able to utilize dibenzothiophene (DBT) as a sole source of sulphur. The carbon skeleton of DBT is not metabolized and is conserved as 2-hydroxybiphenyl (HBP), which accumulates in the medium. This phenotype is due to the expression of the plasmid-encoded DBT-desulphurization (dsz) operon, which encodes three proteins, DszA, B and C. In this paper it is shown, using [35S]DBT radiolabelling studies, that sulphur is released in the form of inorganic sulphite. The pathway of DBT desulphurization is described in detail. In summary, DszC catalyses the stepwise S-oxidation of DBT, first to dibenzothiophene 5-oxide (DBTO) and then to dibenzothiophene 5,5-dioxide (DBTO2); DszA catalyses the conversion of DBTO2 to 2-(2′-hydroxyphenyl)benzene sulphinate (HBPSi-) and DszB catalyses the desulphination of HBPSi- to give HBP and sulphite. Studies with cell-free extracts show that DszA and DszC, but not DszB, require NADH for activity. 18O2-labelling studies show that each incorporated oxygen atom is derived directly from molecular oxygen. These results are consistent with the role of DszC as a mono-oxygenase, of DszA as an apparently unique enzyme which catalyses the reductive hydroxylation of DBTO2 leading to cleavage of the thiophene ring, and of DszB as an aromatic sulphinic acid hydrolase.

Metabolism of dibenzothiophene and naphthalene in Pseudomonas strains: complete DNA sequence of an upper naphthalene catabolic pathway.

Abstract: From a soil isolate, Pseudomonas strain C18, we cloned and sequenced a 9.8-kb DNA fragment that encodes dibenzothiophene-degrading enzymes. Nine open reading frames were identified and designated doxABDEFGHIJ. Collectively, we refer to these genes as the DOX pathway. At the nucleotide level, doxABD are identical to the ndoABC genes that encode naphthalene dioxygenase of Pseudomonas putida. The DoxG protein is 97% identical to NahC (1,2-dihydroxynaphthalene dioxygenase) of P. putida. DoxE has 37% identity with cis-toluene dihydrodiol dehydrogenase. DoxF is similar to the aldehyde dehydrogenases of many organisms. The predicted DoxHIJ proteins have no obvious sequence similarities to known proteins. Gas chromatography with a flame ionization detector and mass spectroscopy confirmed that the DOX proteins convert naphthalene to salicylate and converting phenanthrene to 1-hydroxy-2-naphthoic acid. doxI mutants convert naphthalene to trans-o-hydroxybenzylidenepyruvate, indicating that the DoxI protein is similar to NahE (trans-o-hydroxybenzylidenepyruvate hydratase-aldolase). Comparison of the DOX sequence with restriction maps of cloned naphthalene catabolic pathway (NAH) genes revealed many conserved restriction sites. The DOX gene arrangement is identical to that proposed for NAH, except that the NAH equivalent of doxH has not been recognized. DoxH may be involved in the conversion of 2-hydroxy-4-(2'-oxo-3,5-cyclohexadienyl)-buta-2,4-dienoat e to cis-o-hydroxybenzylidenepyruvate. doxJ encodes an enzyme similar to NahD (isomerase). Our findings indicate that a single genetic pathway controls the metabolism of dibenzothiophene, naphthalene, and phenanthrene in strain C18 and that the DOX sequence encodes a complete upper naphthalene catabolic pathway similar to NAH.

Recent Advances in Petroleum Microbiology

Abstract: Recent advances in molecular biology have extended our understanding of the metabolic processes related to microbial transformation of petroleum hydrocarbons. The physiological responses of microorganisms to the presence of hydrocarbons, including cell surface alterations and adaptive mechanisms for uptake and efflux of these substrates, have been characterized. New molecular techniques have enhanced our ability to investigate the dynamics of microbial communities in petroleum-impacted ecosystems. By establishing conditions which maximize rates and extents of microbial growth, hydrocarbon access, and transformation, highly accelerated and bioreactor-based petroleum waste degradation processes have been implemented. Biofilters capable of removing and biodegrading volatile petroleum contaminants in air streams with short substrate-microbe contact times ( 2 S and sulfoxides from petrochemical waste streams. Microbes also have potential for use in removal of nitrogen from crude oil leading to reduced nitric oxide emissions provided that technical problems similar to those experienced in biodesulfurization can be solved. Enzymes are being exploited to produce added-value products from petroleum substrates, and bacterial biosensors are being used to analyze petroleum-contaminated environments.

New design approaches to ultra-clean diesel fuels by deep desulfurization and deep dearomatization

Abstract: This paper is a selective review on design approaches and associated catalysis and chemistry for deep desulfurization and deep dearomatization (hydrogenation) of hydrocarbon fuels, particularly diesel fuels. The challenge for deep desulfurization of diesel fuels is the difficulty of removing the refractory sulfur compounds, particularly 4,6-dimethyldibenzothiophene, with conventional hydrodesulfurization processes. The problem is exacerbated by the inhibiting effect of polyaromatics and nitrogen compounds, which exist in some diesel blend stocks on deep HDS. With the new Environmental Protection Agency (EPA) Tier II regulations to cut the diesel sulfur from current 500 ppmw down to 15 ppmw by June 2006, refineries are facing major challenges to meet the fuel sulfur specification along with the required reduction of aromatics contents. The principles and problems for the existing hydrodesulfurization processes, and the concepts, advantages and disadvantages of various new approaches will be discussed. Specifically, the following new design approaches for sulfur removal will be discussed: (1) novel catalysts for ultra-deep hydrodesulfurization under conventional HDS process conditions; (2) new design concept for sulfur-tolerant noble metal catalysts for low-temperature hydrogenation; (3) new desulfurization process by sulfur adsorption and capture under H2; (4) new desulfurization process by selective adsorption at ambient temperature without H2 and a related integrated process concept; (5) oxidative desulfurization in liquid-phase; and (6) biodesulfurization.

Methods and compositions for cellular and metabolic engineering

Abstract: The present invention is generally directed to the evolution of new metabolic pathways and the enhancement of bioprocessing through a process herein termed recursive sequence recombination. Recursive sequence recombination entails performing iterative cycles of recombination and screening or selection to “evolve” individual genes, whole plasmids or viruses, multigene clusters, or even whole genomes. Such techniques do not require the extensive analysis and computation required by conventional methods for metabolic engineering.