TECHNOLOGY FOCUS - BIOLOGY - Preferred Component: At least one of the microorganism species is a species of Desulfuromonas. At least one of the first, second and third microbial consortiums comprises at least one species of Desulfuromonas. The first-bite microbial consortium or the downstream microbial consortium comprises one or more species of Acetobacterium.    TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Component: Both the first-bite microbial consortium and the downstream microbial consortium are anaerobic microbial consortiums. At least one of the first-bite metabolic products is the starting hydrocarbon metabolic product. The isolated microbial consortia further comprise an intermediate microbial consortium that converts the first-bite metabolic product into the starting hydrocarbon metabolic product. The intermediate microbial consortium comprises microorganism species that converts the first-bite metabolic product into the starting hydrocarbon metabolic product through intermediate metabolic products. The isolated microbial consortia may comprise a first microbial consortium that converts the starting hydrocarbon into one or more intermediate compounds; a second microbial consortium that converts type(s) of the intermediate compounds into carbon dioxide (CO2) and hydrogen (H2); and a third microbial consortium that converts the CO2 and H2 into methane and water. The first, second and third consortiums comprise anaerobic microorganisms. The second microbial consortium converts the type of the intermediate compounds into acetate. The third microbial consortium converts the acetate into methane and water. The third microbial consortium comprises a first group of microorganisms that convert acetate into carbon dioxide and free hydrogen, and a second group of microorganisms that convert the carbon dioxide and free hydrogen into methane and water.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: The intermediate metabolic products comprise carbon monoxide (CO), or CO2.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The starting hydrocarbon comprises coal, oil, kerogen, peat, lignite, oil shale, tar sands, bitumen, or tar. The downstream metabolic product comprises an organic acid, an alcohol, an amine, a straight or branched hydrocarbon, or an aromatic hydrocarbon. It preferably comprises methane. The starting hydrocarbon metabolic product and the intermediate compound comprise a formate compound, an acetate compound, a benzoate compound, the alcohol, or the organic acid. EXAMPLE - No suitable example given.