Method for producing aldehyde from co2

Abstract

The invention provides recombinant microorganisms capable of producing isobutyraldehyde using CO 2 as a carbon source. The invention further provides methods of preparing and using such microorganisms to produce isobutyraldehyde.

1 - 20 . (canceled) 
     
     
         21 . A method of producing an aldehyde from CO 2  via an engineered recombinant microorganism, the method comprising:
 growing a culture of a recombinant photosynthetic cyanobacteria microorganism, the microorganism having exogenous nucleic acid sequences that express enzymes that catalyze conversion of 2-keto acids to isobutyraldehyde;   providing CO 2  as a carbon source to the culture;   photosynthetically producing isobutyraldehyde from the CO 2  and via metabolic pathways of the recombinant photosynthetic cyanobacteria microorganism that catalyze conversion of metabolic intermediates, including 2-keto acids, to isobutyraldehyde; and   removing isobutyraldehyde from the culture.   
     
     
         22 . The method of  claim 21 , wherein the recombinant photosynthetic cyanobacteria microorganism includes a photoautotroph. 
     
     
         23 . The method of  claim 21 , wherein the recombinant photosynthetic cyanobacteria microorganism includes Synechococcus elongatus. 
     
     
         24 . The method of  claim 21 , wherein the 2-keto access includes at least one of the following: 2-ketobutyrate, 2-ketoisovalerate, 2-ketovalerate, 2-keto-3-methylvalerate, 2-keto-4-methyl-pentanoate, and phenylpyruvate. 
     
     
         25 . The method of  claim 21 , wherein the CO 2  is the sole carbon source for the culture. 
     
     
         26 . The method of  claim 21 , wherein the step of removing the isobutyraldehyde includes evaporating the isobutyraldehyde from the culture. 
     
     
         27 . The method of  claim 22 , further comprising condensing the evaporated isobutyraldehyde. 
     
     
         28 . The method of  claim 21 , wherein the exogenous nucleic acid sequences express a 2-ketoisovalerate decarboxylase, is obtained from Lactococcus lactis and represents an amino acid sequence with at least 85% identity SEQ ID NO:19 to catalyze the conversion of 2-ketoisovalerate to isobutyraldehyde. 
     
     
         29 . The method of  claim 21 , wherein isobutanol is not produced by the recombinant photosynthetic cyanobacteria microorganism at a level higher than 50 mg/L. 
     
     
         30 . The method of  claim 21 , further comprising re-suspending the culture in a fresh medium when isobutyraldehyde production rate falls below a threshold production rate. 
     
     
         31 . The method of  claim 30 , wherein the threshold production rate is no higher than 2,500 μg l −1  h −1 . 
     
     
         32 . The method of  claim 21 , wherein isobutyraldehyde production rate is at least 6,230 μg l −1  h −1 . 
     
     
         33 . The method of  claim 21 , further comprising maintaining an isobutyraldehyde concentration in the culture at or below 750 mg/l. 
     
     
         34 . The method of  claim 33 , further comprising maintaining the isobutyraldehyde concentration in the culture at or below 20 mg/l.