NOVELTY - Producing product alcohol in fermentation process, involves (a) providing a fermentation broth comprising recombinant microorganism that produces a product alcohol from a fermentable carbon source, (b) contacting the fermentation broth with a fermentable carbon source, hence the recombinant microorganism consumes the fermentable carbon source and produces the product alcohol, and (c) contacting the fermentation broth with fatty acids derived from biomass at a step in the fermentation process.    USE - The method is useful for producing product alcohol, preferably butanol (claimed) which is used in beverage (ethanol), fuel, reagents, solvents and antiseptics.    ADVANTAGE - The method is rapid and environmentally-friendly, and has improved productivity.    DETAILED DESCRIPTION - Method for producing product alcohol in fermentation process, involves (a) (i) providing a fermentation broth comprising recombinant microorganism that produces a product alcohol from a fermentable carbon source, where the recombinant microorganism comprises reduction or elimination of pyruvate decarboxylase activity, (ii) contacting the fermentation broth with a fermentable carbon source, hence the recombinant microorganism consumes the fermentable carbon source and produces the product alcohol, and (iii) contacting the fermentation broth with fatty acids derived from biomass at a step in the fermentation process, where at least one of growth rate and fermentable carbon consumption of the recombinant microorganism is greater in the presence of the fatty acids than the growth rate and/or the fermentable carbon consumption of the recombinant microorganism is in the absence of the fatty acids, (b) (i) providing biomass comprising a fermentable carbon source and oil, (ii) converting at least a portion of the oil into fatty acids to form a biomass comprising the fatty acids, (iii) contacting the biomass with a fermentation broth comprising a recombinant microorganism capable of producing a product alcohol from a fermentable carbon source, and (iv) contacting the fatty acids with the fermentation broth, or (c) (i) providing a feedstock, (ii) liquefying feedstock to create a feedstock slurry, (iii) separating the feedstock slurry to produce a product comprising an aqueous layer comprising a fermentable carbon source, an oil layer, and a solids layer, (iv) obtaining an oil from the oil layer and converting at least a portion of the oil into fatty acids, (v) feeding the aqueous layer to a fermentation vessel containing a fermentation broth comprising a recombinant microorganism capable of producing a product alcohol from a fermentable carbon source, where the recombinant microorganism comprises a reduction or elimination of pyruvate decarboxylase activity, (vi) fermenting the fermentable carbon source of the aqueous layer to produce the product alcohol, and (vii) contacting the fermentation broth with the fatty acids. An INDEPENDENT CLAIM is included for composition, which comprises recombinant microorganism comprising a reduction or elimination of pyruvate decarboxylase activity and fatty acids.