The difference here is the type of fuel that comes out of the microbes: butanol.
butanol-a promising next-generation biofuel-packs more energy than ethanol and can be shipped via oil pipelines.
These organisms produce organic molecules that have been used to make butanol and other liquid fuels.
butanol can be mixed with gasoline in high percentages.
Two molecules of butanol are formed for each molecule of acetone.
British Dictionary definitions for butanol
a colourless substance existing in four isomeric forms. The three liquid isomers are used as solvents for resins, lacquers, etc, and in the manufacture of organic compounds. Formula: C4H9OH Also called butyl alcohol
(by'tə-nôl', -nōl', nŏl') Either of the two butyl alcohols that are derived from butane and have a straight chain of carbon atoms. Butanols are used as solvents and in organic synthesis. Chemical formula: C4H10O.