Fuels and Chemicals from Keto Acids

Kinetic analysis of native AHAS from S. elongatus PCC7942 demonstrated a preferred selectivity toward a-ketobutyrate. 

It is generally accepted that cyanobacterial TCA cycle is not very active under phototrophic conditions. A recent study further proved that it operates in a bifurcated way [112]. However, the bifurcated pattern switches to a dominantly cyclic pattern by introducing an ethylene-forming enzyme from Pseudomonas. Ethylene can be sustainably and efficiently produced from 2-oxoglutarate while also activating the TCA cycle metabolism. The enhanced flux via the remodeled TCA is 37% of the total fixed carbon which is higher than the 13% found in wild type. This result indicates that the metabolic malleability of the cyanobacterial TCA cycle depends on what it produces. 

Although it is promising, there are still a number of challenges that need to be overcome to see cyanobacteria become an industrial microorganism. The productivity of metabolites of interest is still low and needs to be increased through both metabolic engineering to create improved strains and development of more efficient bioreactors. With advances in both fields, cyanobacteria may become a valuable addition to the current industrial microbial platforms. 

(2009) Solar energy conversion efficiencies in photosynthesis minimizing the chlorophyll antetmae to maximize efficiency. Plant Sci., 177 (4), 272-280. 

and Ort, D.R. (2008) What is the maximum efficiency with which photosynthesis can convert solar energy into biomass Curr. Opin. Biotechnol, 19 (2), 153-159, 

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