A method of converting an acid to its corresponding alcohol using a microbial culture in the presence of a substrate comprising carbon monoxide (CO) or CO and hydrogen. The method comprises: (a) Culturing a carboxydotrophic bacteria in the presence of the substrate to produce the acid; (b) Perturbing the culture so that the microbial culture switches from a production/growth phase to a conversion phase that converts the acid to its corresponding alcohol; and (c) Recovering the alcohol. The microbe can be Clostridium autoethanogenum and the acid/alcohol combination can be acetate and ethanol. The perturbation step can be (i) adjusting the pH of the medium, (ii) adjusting the ORP of the medium, (iii) adding a second acid, (iv) adding a reducing agent, (v) adjusting the CO concentration or (vi) adjusting the CO partial pressure.
