Method for the production of 1-butanol

A method for the production of 1-butanol comprising:

• a) providing a recombinant microbial production host cell which is tolerant to 1-butanol, and wherein the recombinant microbial host cell comprises heterologous DNA molecules encoding polypeptides that catalyze each of the following substrate to product conversions:
• i) acetyl-CoA to acetoacetyl-CoA;
• ii) acetoacetyl-CoA to 3-hydroxybutyryl-CoA;
• iii) 3-hydroxybutyryl-CoA to crotonyl-CoA;
• iv) crotonyl-CoA to butyryl-CoA;
• v) butyryl-CoA to butyraldehyde;
• and
• vi) butyraldehyde to 1-butanol;
• b) seeding the production host of (a) into a fermentation medium comprising at least one fermentable carbon substrate to create a fermentation culture;
• c) growing the production host in the fermentation culture at a first temperature for a first period of time determined by a change in at least one monitored metabolic parameter of the fermentation culture;
• d) lowering the temperature of the fermentation culture to a second temperature for a second period of time determined by a change in at least one monitored metabolic parameter of the fermentation culture;
• e) optionally lowering the temperature of the fermentation culture to a third temperature for a third period of time determined by a change in at least one monitored metabolic parameter of the fermentation culture;
• wherein steps (c), (d) and (e) are optionally repeated to maintain a desired rate of 1-butanol production.