Enzymatic methods for butanol production

A process for producing n-butanol, comprising:

• A) mixing water, lactate, an enzyme mixture, at least one cofactor and at least one coenzyme, to prepare a reaction mixture, wherein the enzyme mixture comprises:
• lactate dehydrogenase EC 1.1.1.27 and/or EC 1.1.1.28,
• pyruvate dehydrogenase EC 1.2.1.51, EC 1.2.4.1, EC 2.3.1.12 and/or EC 1.8.1.4, acetoacetyl-CoA thiolase EC 2.3.1.9,
• 3-hydroxybutyryl-CoA dehydrogenase EC 1.1.1.35 and/or EC 1.1 0.1.157,
• enoyl-CoA hydratase EC 4.1.1.55 and/or EC 4.2.1.17,
• butyryl-CoA dehydrogenase EC 1.3.1.44, EC 1.3.1.86 and/or 1.3.8.1,
• butanal dehydrogenase EC 1.2.1.57 and/or EC 1.2.1.10,
• alcohol dehydrogenase EC 1.1.1.1 and/or EC 1.1.1.2,
• pyruvate formate lyase EC 2.3.1.54,
• formate dehydrogenase EC 1.2.1.43,
• acetolactate synthase EC 2.2.1.6,
• ketoacid reductoisomerase EC 1.1.1.86,
• dihydroxy acid dehydratase EC 4.2.1.9,
• 2-oxoisovalerato dehydrogenase EC 1.2.1.25 and/or EC 1.2.4.4, and
• isobutyryl-CoA mutase EC 5.4.99.13;
• B) catalytically reacting the reaction mixture at a temperature of from 15 to 37° C. for an amount of time sufficient to cause conversion of lactate into n-butanol;
• and
• C) separating the n-butanol from a reactant obtained by the catalytic conversions in B), wherein the conversion of lactate into n-butanol in B) is conducted with no overall loss or gain of Nicotinamide Adenine Dinucleotide (NAD+) and Reduced Nicotinamide Adenine Dinucleotide (NADH) and/or Nicotinamide Adenine Dinucleotide Phosphate (NADP+) and Reduced Nicotinamide Adenine Dinucleotide Phosphate (NADPH), and less than a stoichiometric amount of NAD+ and/or NADP+ is employed to obtain a n-butanol from lactate with a conversion efficiency of 98 to 100%.