TECHNOLOGY FOCUS - BIOLOGY - Preferred Method: The acetoacetyl-CoA synthase gene encodes an enzyme that catalyzes a reaction that converts two acetyl-CoA molecules into acetoacetyl-CoA, where the acetoacetyl-CoA synthase gene is the thiolase gene (the thlA gene) derived from Clostridium acetobutylicum. The acetoacetyl-CoA synthase gene encodes a protein comprising either the amino acid sequence of SEQ ID NO: 2 (comprising a fully defined sequence of 392 amino acids, as given in the specification) or an amino acid sequence having greater than or equal to 80% identity to the amino acid sequence of SEQ ID NO: 2 and has a function of synthesizing acetoacetyl-CoA from two acetyl-CoA molecules. The acetoacetyl-CoA synthase gene encodes an enzyme that catalyzes a reaction that converts acetyl-CoA and malonyl-CoA into acetoacetyl-CoA, where acetoacetyl-CoA synthase gene is a gene (the orfN gene) derived from a Streptomyces microorganism. The acetoacetyl-CoA synthase gene encodes a protein comprising either the amino acid sequence of SEQ ID NO: 1 (comprising a fully defined sequence of 329 amino acids, as given in the specification) or an amino acid sequence having greater than or equal to 80% identity to the amino acid sequence of SEQ ID NO: 1 and has a function of synthesizing acetoacetyl-CoA from malonyl-CoA and acetyl-CoA. The recombinant microorganism is obtained via introduction of genes including the genes involved in 2-propanol biosynthesis, where the gene to be introduced does not exist in the microorganism as an endogenous gene. Preferred Components: The group of genes involved in 2-propanol biosynthesis consists of the acetoacetyl-CoA transferase gene, the acetoacetic acid decarboxylase gene and the isopropanol dehydrogenase gene. The acetoacetyl-CoA transferase gene is the ctfA or ctfB gene derived from Clostridium acetobutylicum. The acetoacetic acid decarboxylase gene is the adc gene derived from Clostridium acetobutylicum. The isopropanol dehydrogenase gene is the pdh gene derived from Clostridium beijerinckii. The recombinant microorganism is obtained from an Escherichia coli host strain, where the Escherichia coli strain is an Escherichia coli K strain. EXAMPLE - Escherichia coli BL21 (DE3) strains was transformed with pCDFDuet-thiA, pETDuet-ADC-ctfAB and pCOLADuet-PDH plasmids. The resulting recombinant Escherichia coli strains was designated as E/BL21. The solution containing ammonium chloride (7g), mono potassium phosphate (1.5g), disodium phosphate (1.5g), potassium sulfate (0.35 g), magnesium sulfate heptahydrate (0.17 g), yeast extract (5 g) and trace element solution (0.8 ml) (including ferrous sulfate heptahydrate (40 g), manganese sulfate (10 g), aluminum sulfate (28.3 g), cobalt chloride (4 g), zinc sulfate (2 g), sodium molybdate dihydrate (2 g), cuprous chloride (1 g) and boric acid (0.5 g)) was dissolved in deionized water (0.8 l), and the pH was adjusted to 7 with ammonium hydroxide. The total amount of the medium was filled with deionized water (up to 1 l), to obtain SD-7 medium. The solution containing ammonium chloride (7g), mono potassium phosphate (7.5g), disodium phosphate (7.5g), potassium sulfate (0.85 g), magnesium sulfate heptahydrate (0.17 g), yeast extract (10 g) and trace element solution (0.8 ml) was dissolved in deionized water (0.8 l), and the pH was adjusted to 7 with ammonium hydroxide. The total amount of the medium was filled with deionized water (up to 1 l), to obtain SD-8 medium. Single colonies of the obtained recombinant Escherichia coli strains were inoculated in SD-7 medium (5 ml) containing 2% glucose and the culture was incubated at 37 degrees C overnight. The culture (500 mu l) was transferred into Erlenmeyer flask with buffer (having 50 ml of SD-8 medium containing 2% glucose) and the flask was shaken rotationally at 37 degrees C and 130 rpm. After isopropyl-beta-D-thiogalactopyranoside (IPTG) (0.1 mM) was added, a portion of culture solution (5 ml) was periodically dispensed into a screw-capped test tube. The resultant was then stored at -30 degrees C. The glucose was further added to a final concentration of 2% in 24 hours after the addition of IPTG. The culture solution stored at -30 degrees C was thawed at room temperature. After the broth was thoroughly suspended with a vortex, the culture solution (1 ml) was transferred into an eppendorf tube and centrifuged at 13000rpm for 10minutes at 4 degrees C, and the supernatant was removed. The remaining culture solution (4 ml) was subjected to centrifugation at 1000 g at room temperature for 5 minutes. The supernatant (2 ml) was transferred into a 20-ml headspace crimp vial, the vial was capped, and the vial was then transferred into a warm bath at 60 degrees C, to obtain 2-butanol and other components from the culture.