Patent ID: 8293509

Claim:
A process for producing one more alcohols, the process comprising: a. in a first bioreactor, carrying out a first fermentation of a gaseous substrate that comprises CO and a gaseous co-substrate, wherein the first fermentation produces a first fermentation broth comprising one or more acids and optionally one or more alcohols; b. passing at least a portion of the one or more acids to a second bioreactor; c. in the second bioreactor, carrying out a second fermentation of a substrate comprising a carbohydrate, wherein the second fermentation produces a second fermentation broth comprising one or more alcohols, and wherein at least a portion of the one or more acids is utilised in the second fermentation to produce a gaseous co-substrate; d. passing at least a portion of the gaseous co-substrate produced in step (c) to the first bioreactor, wherein at least a portion of the gaseous co-substrate is utilized as a co-substrate in the first fermentation.