TECHNOLOGY FOCUS - BIOTECHNOLOGY - Recombinant Method (disclosed): The recombinant host cell is prepared using recombinant technology. Preferred Cell: The host cells (A1) and (A2) further comprise polynucleotides encoding polypeptides that catalyzes the substrate to product conversions: (2,3-dihydroxyisovalerate to alpha -ketoisovalerate, alpha -ketoisovalerate to isobutyraldehyde, and isobutyraldehyde to isobutanol; or 2,3-dihydroxyisovalerate to alpha -ketoisovalerate, alpha -ketoisovalerate to isobutyryl-CoA, isobutyryl-CoA to isobutyraldehyde, and isobutyraldehyde to isobutanol; or 2,3-dihydroxyisovalerate to alpha -ketoisovalerate, alpha -ketoisovalerate to valine, valine to isobutylamine, isobutylamine to isobutyraldehyde, and isobutyraldehyde to isobutanol; or acetolactate to acetoin, acetoin to 2,3-butanediol, and 2,3-butanediol to 2-butanone; or acetolactate to acetoin, acetoin to 2,3-butanediol, 2,3-butanediol to 2-butanone, and 2-butanone to 2-butanol. The host cell further comprises polynucleotides encoding polypeptides that catalyzes the substrate to product conversions: acetolactate to acetoin, acetoin to 3-amino-2-butanol, 3-amino-2-butanol to 3-amino-2-butanol phosphate, and 3-amino-2-butanol phosphate to 2-butanone. The host cell (A1) and (A2) are selected from bacterium, cyanobacterium, filamentous fungus, and yeast. The host cell is a member of a genus selected from Clostridium, Zymomonas, Escherichia, Salmonella, Rhodococcus, Pseudomonas, Bacillus, Lactobacillus, Enterococcus, Alcaligenes, Klebsiella, Paenibacillus, Arthrobacter, Corymbacterium, Brevibacterium, Pichia, Candida, Hansenula, Issatchenkia, Kluyveromyces, and Saccharomyces (preferably Escherichia coli, Lactobacillus plantarum and Saccharomyces cerevisiae. In the host cells (A1) and (A2), the polypeptide is expressed in the host cell cytosol. The polypeptide that catalyzes a substrate to product conversion of pyruvate to acetolactate is acetolactate synthase. The acetolactate synthase has at least 80% identity to an amino acid sequence selected from SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 16, or SEQ ID NO: 18, all as available on WIPO website, where expression of pyruvate decarboxylase in the host cell is decreased or eliminated. The host cell comprises a deletion, mutation, and/or substitution in an endogenous polynucleotide encoding a polypeptide having pyruvate decarboxylase activity. The polynucleotide encoding a polypeptide which catalyzes the conversion of pyruvate to acetolactate is integrated into an endogenous polynucleotide encoding a polypeptide having pyruvate decarboxylase activity, where the expression of glycerol-3-phosphate dehydrogenase or Fra2 in the host cell is decreased or eliminated. The polynucleotide is integrated into the chromosome at the pyruvate decarboxylase 1(PDC1)-thioredoxin I (TRX1) intergenic region.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred method: The method (M1) further involves contacting the fermentation broth with an extractant to produce a two-phase fermentation mixture; contacting the fermentation broth with an organic acid and an enzyme capable of esterifying the alcohol with the organic acid; and vaporizing at least a portion of the fermentation broth to form a vapor stream comprising water and alcohol. Preferred Components: The extractant comprises fatty acids which are derived from corn oil or soybean oil; a water immiscible organic extractant selected from 12-22C fatty alcohols, 12-22C fatty acids, esters of 12-22C fatty acids, 12-22C fatty aldehydes, and 12-22C fatty amides; and oleyl alcohol. EXAMPLE - No suitable example given.