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Results demonstrate an unique anerobic oxidation of n-alkanes to form (1-methylpentylsuccinate) in a denitrifying bacterium growing on n-hexanes as the only organic substrate. Data reveal that n-hexane is activated by a radical reaction and added on to fumarate cosubstrate to give (1-methylpentylsuccinate).

Two new types of sulfate-reducing bacteria which can oxidize alkylbenzenes, o- and m-xylenes have been isolated. The alkylbenzenes were consumed during the growth of the sulfate-reducing enrichment culture with crude oil as the only source of the organic substrates. Two mesophilic, rod-shaped strains, oXyS1 and mXyS2 were detected with o- and m-xylenes as the organic substrates. The resulting 16S rRNA analysis revealed that strains belong to the delta subclass of Proteobacteria.

Hybridization of nucleic acids from a sulfate-enrichment culture growing anaerobically on crude oil revealed the presence of a species of sulfate-reducing bacteria. Fluorescent labeling studies showed that the bacteria do not utilize aromatic hydrocarbons, indicating that the cells do not belong to known Desulfovibrio species. More than 95% of the cells in the culture hybridized with a modified probe, suggesting that the cells may belong to the oxidizing, alkylbenzene-utilizing sulfate-reducing species.

Pure cultures of denitrifying bacteria have the ability to grow under anaerobic conditions using crude oil as a source of organic substrates. The bacteria utilizes toluene, ethylbenzene, and m-xylene from the crude oil and o-xylene and p-xylene to a smaller extent. The compounds used by the bacteria are the most water-soluble oil hydrocarbons and represent groundwater pollutants at places contaminated with oil. The amount of hydrocarbons utilized by the bacteria is however, very small.

SW2 and L7, two purple bacterial strains consisting of small rod-shaped nonmotile cells, oxidize colorless ferrous iron to brown ferric iron through a unique phototrophic metabolism pathway, under anoxic conditions. SW2 and L7 also utilize monocarboxylic acids, fructose and glucose, and acetate, glucose and pyruvate, respectively, as phototrophic growth substrates, and display absorption peaks characteristic of bacteriochlorophyll a. The ferrous iron contributes electrons to the anoxygenic phototrophs that are responsible for the accumulation of early banded-iron levels in an anoxic biosphere.

The isolation of a marine sulfate-reducing bacterium that anaerobically degrades toluene was reported. It was demonstrated by measurement of degradation balance that toluene was completely oxidized to CO2. The presence of carbon monoxide dehydrogenase and formate dehydrogenase indicated a terminal oxidation of acetyl coenzyme A via the CO dehydrogenase pathway. However, the results of the consumption of hypothetical intermediates do not support a degradation of toluene via the introduction of a hydroxyl group into the ring. The designation Desulfobacula toluolica is proposed for the new sulfate-reducing bacterium.

Pure and enrichment cultures of nitrate-reducing bacteria grow with iron as the sole or additional electron donor under anaerobic conditions. However, the oxidation of ferrous iron by the bacteria is unobservable in the absence of nitrates or in heat-inactivated cultures. The product of nitrate reduction is dinitrogen. The bacteria are probably responsible for the production of ferric iron in the suboxic region of aquatic sediments.

Research discusses the isolation of sulfate-reducing bacteria from marine sediments that can utilize ethylbenzene anaerobically as the only source of organic carbon for their growth. These bacteria show ethylbenzene-dependent reduction of sulfate to sulfide and exhibit a cell type that form gas vesicles in the stationary phase of growth.