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Oil exploration causes huge volumes of oily wastewater and produced waters show a wide range of salinities with spilled brine inhibiting plant growth. A highly enriched halophilic culture was established with benzene as the sole carbon source using brine soil obtained from an oil production facility and community structure analysis showed that Marinobacter spp. was a dominant member of the enrichment.

Microbial community composition related to benzene oxidation under in situ Fe(III)-reducing conditions in a petroleum-contaminated aquifer located in Bemidji, MN, was studied. Findings indicated that specific Geobacter spp are associated with the capacity for benzene degradation in the petroleum-contaminated aquifer. Evidence supporting this conclusion includes the significant rise in the number of Geobacteraceae within the zone of benzene degradation and specific enrichment of a tight phylogenetic cluster of Geobacter spp in the zone of benzene degradation that is not found in the uncontaminated sediments.

Research was conducted to examine the factors involved in the uncoupling of substrate oxidation by investigating the reactions catalyzed by naphthalene dioxygenase (NDO) with a smaller substrate, namely, benzene. A trace amount of cis-benzene 1,2-dihydrodiol was developed by a coupling reaction. Results demonstrate that in the presence of benzene, NDO catalyzes a partial uncoupling reaction that results in the formation of cis-benzene 1,2-dihydrodiol and hydrogen peroxide.

Research was conducted to examine the link between nitrate reduction and benzene biodegradation in enrichment and transfer cultures obtained from the original nitrate-amended microcosms. Nitrate reduction and benzene biodegradation took place concurrently at a constant ratio of 10 mol of nitrate consumed per mol of benzene degraded. Results indicate that benzene degradation is coupled more tightly to nitrate reduction to nitrite than to nitrite reduction to nitrogen gas.

A study was conducted to analyze the metabolism of benzene, toluene and xylene (BTX) hydrocarbons in soil. Microtox toxicity assays were carried out on extracts of soil samples incubated with benzene, toluene and p-xylene mixtures. Total radiocarbon bound in the soil was then obtained using the web combustion of soil samples. Results indicated that xylenes are cometabolized in BTX mixtures applied to soil before being mineralized because of the diversity of soil microorganisms.

A Bacillus sphaericus monooxygenase capable of catalyzing the first two steps in the degradation of p-nitrophenol (PNP) via 4-nitrocatechol and 1,2,4-trihydroxybenzene (THB) was identified and characterized. Nitrite was produced stoichiometrically by PNP-grown cells. Results of the THB stimulation of oxygen consumption reveal that THB acts as a substrate for a ring cleavage dioxygenase. It was also observed that a single monooxygenase system was capable of catalyzing the initial hydroxylation of PNP and the oxidative release of the nitro group from the 4-nitrocatechol.

Pseudomonas strains with the ability to degrade isopropylbenzene (IPB) and tricholoroethane (TCE) are developed using an ipb DNA module. Results from the localization of transcriptional start points of the ipbA genes indicate that ipb gene expressions are regulated in response to IPB at the transcriptional level. The mutant Pseudomonas sp. strain JR1 exhibited the ability to efficiently degrade TCE after the induction of TCE-oxidizing oxygenase.

Aquifer sediments taken from the sulfate-reducing zone of a jet fuel-contaminated aquifer were treated with benzene to further investigate the potential for anaerobic benzene degradation coupled to sulfate reduction in aquifers contaminated with petroleum. The findings indicate that the persistence of benzene under sulfate-reducing conditions in the contaminated aquifer was due to the absence of benzene-oxidizing sulfate reducers in the aquifer sediments and not to the failure of the reducers to grow and metabolize under freshwater conditions.

The physiological properties of a mixed culture which effectively dechlorinates trichlorobenzenes were investigated as well as the effects of various specific inhibitors and alternative electron acceptors. In situ probing revealed that two major subpopulations within the microbial consortium were phylogenetically affiliated with a sublineage within the Desulfovibrionaceae and Proteobacteria. Sulfate strongly inhibited the dechlorination of trichlorobenzenes. Molybdate at a concentration of 1mM also inhibited the dechlorination of trichlorobenzenes.

A methanogenic microbial consortium which can reductively dechlorinate 1,2,4-trichlorbenzene (1,2,4-TCB) was enriched from a mixture of polluted sediments. Lactate, which was employed as an electron donor during the enrichment, was transformed into methane via proponate and acetate. Hexachlorobenzen and polychlorinated biphenyls were dechlorinated after a lag phase of ca. 15 days, indicating a dechlorination pattern that is different from those for lower chlorinated benzenes. Results indicated that the consortium has at least three distinct dechlorination activities.

Rhodococcus opacus is a gram-positive bacteria that uses phenols, halogenated benzenes, and benzoates as its sole source of carbon and energy. The R. opacus GM-14 strain is able to use saturated aqueous solutions of benzene and chlorobenzene. The bacterial strain releases stoichiometric amounts of chloride when grown on chlorobenzene, 1,3-dichlorobenzene, and isomers of monochlorophenol. Most of the chloride is released from 1,4-dichlorobenzene. The growth rate of R. opacus GM-14 on different substrates is different.

P. putida RE204 degrades benzothiophene by forming enzymes that catalyze reactions of the isopropyl benzene catabolic pathway. The biotransformation occurs at either the benzene ring or the thiophene ring. The product of one reaction will be a substrate for the next isopropyl dioxygenase of the pathway. Reductive dioxygenase reactions involve the formation of complex mixtures of the products.

The study examined benzene degradation in methanogenic sediments from an aromatic hydrocarbon-contaminated aquifer in Ponca City, OK. Conversion of [14C]benzene to 14CH4 and 14CO2 occurred without an apparent lag. This indicates that the microbial population was adapted for benzene degradation and that in situ degradation of benzene is possible. The fact that sediments at the site have long been exposed to comparatively high concentrations of benzene may contribute to the active conversion of benzene to methane in the sediments.

The consecutive hydroxylations led to the invention of toluene 4-monooxygenase (T4MO) of Pseudomonas mendocina KR1, toluene 3-monooxygenase (T3MO) of Ralstonia pickettii PKO1 and toluene ortho-monooxygenase(TOM) of Burkholderia cepacia G4 that changed benzene to phenol, catechol and 1,2,3-trihydroxybenzene. The very heavy liquid chromatography and mass spectrometry together were used to discover the catechol and 1,2,3-trihydroxybenzene products.