Biological production of organic compounds

Abstract

Strains of cyanobacteria that produce high levels of alpha ketoglutarate (AKG) and pyruvate are disclosed herein. Methods of culturing these cyanobacteria to produce AKG or pyruvate and recover AKG or pyruvate from the culture are also described herein. Nucleic acid sequences encoding polypeptides that function as ethylene-forming enzymes and their use in the production of ethylene are further disclosed herein. These nucleic acids may be expressed in hosts such as cyanobacteria, which in turn may be cultured to produce ethylene.

We claim: 
     
         1 . A method for producing alpha ketoglutarate (AKG) or pyruvate, comprising:
 a) culturing a cyanobacterial cell that lacks a functional ADP-glucose pyrophosphorylase (AGP) enzyme under conditions that allow for AKG or pyruvate production, and   b) recovering the AKG or pyruvate from the cyanobacterial cell culture.   
     
     
         2 . The method of  claim 1 , wherein the cyanobacterial cell does not express a functional glgC gene. 
     
     
         3 . The method of  claim 1 , wherein the cyanobacterial cell is a  Synechocystis  cell. 
     
     
         4 . The method of  claim 1 , wherein the cyanobacterial cell is a  Synechocystis  sp. PCC 6803 cell. 
     
     
         5 . The method of  claim 1 , wherein the cyanobacterial cell is cultured in media that does not contain nitrogen. 
     
     
         6 . The method of  claim 5 , wherein the concentration of nitrogen in the media is less than about 200 μM. 
     
     
         7 . The method of  claim 6 , further comprising a step of adding nitrogen to the media at a final concentration of less than about 1 mM. 
     
     
         8 . The method of  claim 6 , wherein the cyanobacterial cell is cultured under a light intensity of at least about 350 μE m −2 s −1 . 
     
     
         9 . The method of  claim 6 , wherein the cyanobacterial cell is cultured under a light intensity of at least about 600 μE m −2 s −1 . 
     
     
         10 . The method of  claim 1 , wherein the AKG concentration in the culture is greater than 100 mg per liter. 
     
     
         11 . The method of  claim 1 , wherein the AKG concentration in the culture is greater than 1000 mg per liter. 
     
     
         12 . The method of  claim 1 , wherein the cyanobacterial cell exhibits at least a 10,000-fold increase in AKG production when compared to a wild type cell. 
     
     
         13 . The method of  claim 1 , wherein the pyruvate concentration in the culture is greater than 1 g per liter. 
     
     
         14 . The method of  claim 1 , wherein the pyruvate concentration in the culture is greater than 100 g per liter. 
     
     
         15 . The method of  claim 1 , wherein the cyanobacterial cell exhibits at least a 10,000-fold increase in pyruvate production when compared to a wild type cell. 
     
     
         16 . A cyanobacterial cell that lacks a functional ADP-glucose pyrophosphorylase (AGP) enzyme and produces 10,000-fold more AKG or pyruvate when compared to a wild type cell. 
     
     
         17 . The cyanobacterial cell of  claim 16 , wherein the cyanobacterial cell does not express a functional glgC gene. 
     
     
         18 . The cyanobacterial cell of  claim 16 , wherein the cyanobacterial cell is a  Synechocystis  cell. 
     
     
         19 . The cyanobacterial cell of  claim 16 , wherein the cyanobacterial cell is a  Synechocystis  sp. PCC 6803 cell.