Metabolic engineering of cyanobacteria for photosynthetic 3-hydroxypropionic acid production from CO2 using Synechococcus elongatus PCC 7942.
Photosynthetic conversion of CO2 to chemicals using cyanobacteria is an attractive approach for direct recycling of CO2 to useful products. 3-Hydroxypropionic acid (3 HP) is a valuable chemical for the synthesis of polymers and serves as a precursor to many other chemicals such as acrylic acid. 3 HP is naturally produced through glycerol metabolism. However, cyanobacteria do not possess pathways for synthesizing glycerol and converting glycerol to 3 HP. Furthermore, the latter pathway requires coenzyme B12, or an oxygen sensitive, coenzyme B12-independent enzyme. These characteristics present major challenges for production of 3 HP using cyanobacteria. To overcome such difficulties, we constructed two alternative pathways in Synechococcus elongatus PCC 7942: a malonyl-CoA dependent pathway and a β-alanine dependent pathway. Expression of the malonyl-CoA dependent pathway genes (malonyl-CoA reductase and malonate semialdehyde reductase) enabled S. elongatus to synthesize 3 HP to a final titer of 665 mg/L. β-Alanine dependent pathway expressing S. elongatus produced 3H P to final titer of 186 mg/L. These results demonstrated the feasibility of converting CO2 into 3 HP using cyanobacteria.
Institute for Genomics and Proteomics University of California, Los Angeles, CA 90095, USA.
Ethan I
EI
Lan
Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA.
Derrick S
DS
Chuang
Institute for Genomics and Proteomics University of California, Los Angeles, CA 90095, USA.
Claire R
CR
Shen
Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA.
Annabel M
AM
Lee
Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA.
Soo Y
SY
Ro
Institute for Genomics and Proteomics University of California, Los Angeles, CA 90095, USA; Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA. Electronic address: liaoj@seas.ucla.edu.
James C
JC
Liao
D002245:Carbon Dioxide / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000502:physiology; D019344:Lactic Acid / Q000031:analogs & derivatives* / Q000096:biosynthesis; D060847:Metabolic Engineering; D010788:Photosynthesis; D046940:Synechococcus / Q000235:genetics / Q000378:metabolism*; D015091:beta-Alanine / Q000378:metabolism
D015091:beta-Alanine; D002245:Carbon Dioxide; D019344:Lactic Acid; C031601:hydracrylic acid; D002262:Carboxy-Lyases; C019747:aspartate 4-decarboxylase
3-Hydroxypropionate; Biofuel; Cyanobacteria; Malonate semialdehyde