Renewable energy from Cyanobacteria: energy production optimization by metabolic pathway engineering

Abstract

The need to develop and improve sustainable energy resources is of eminent importance due to the finite nature of our fossil fuels. This review paper deals with a third generation renewable energy resource which does not compete with our food resources, cyanobacteria. We discuss the current state of the art in developing different types of bioenergy (ethanol, biodiesel, hydrogen, etc.) from cyanobacteria. The major important biochemical pathways in cyanobacteria are highlighted, and the possibility to influence these pathways to improve the production of specific types of energy forms the major part of this review.

Fig. 1

Sucrose metabolic pathway in cyanobacteria (adapted from Curatti et al. 2008). Sucrose synthase has only been found in heterocyst-forming cyanobacteria. Genes encoding metabolic enzymes: agp, ugp, sps, spp, sus, inv, ces. Metabolites: ADP-Glc, G1P, UDP-Glc, F6Pm, Fru, Suc6P, Glc

Fig. 2

Simplified overview of the fatty acid biosynthesis and some of the competing pathways in cyanobacteria (adapted from Liu et al. 2010a). Pathways not present in cyanobacteria or those which are unknown are indicated with dashed lines. Genes encoding metabolic enzymes: aas, accBCDA, atfA, eno, fabD, fabH, fadD, FASII, gpm, odh, pdh, plsX/plsY, ppc, pps, pta, pyk, thI. Metabolites: 2PG, 3PG, FAEE, OAA, PEP, PYR