The invention relates to the production of alcohols by microbial fermentation, particularly to production of alcohols by microbial fermentation of substrates comprising CO. It more particularly relates to processes for the production of alcohols from their corresponding acids in the presence of a substrate comprising CO. In particular embodiments, a fermentation reaction producing acid(s) and optionally alcohol(s) is perturbed such that at least a portion one or more of acid(s) is converted to alcohol.
