Sourcing
suitable substitutes for fossil fuels is becoming essential to meet current
global energy demands. The utilisation of cyanobacteria for production of
biofuels has received significant attention due to the phototrophic nature of
the organism. In theory, cyanobacteria are an ideal production strain, having minimal
requirements, needing only solar energy, carbon dioxide and minimal amounts of
trace elements for growth. Synechocystis sp.
strain PCC 6803 is a model cyanobacterium for genetic manipulation and has been
widely used to produce a range of biotechnological products such as ethanol [1],
isobutanol [2] and lactic acid [3]. Within the DEMA project [Direct Ethanol
from MicroAlgae]; the utility of this model cyanobacterium to produce ethanol
at a commercializable level is being investigated [4]. A non-native ethanol
biosynthesis pathway has been integrated into Synechocystis PCC 6803 and a library of ethanol-producing mutants
have been generated and characterised, both genetically and phenotypically.
Under laboratory conditions, these strains produce encouraging levels of
ethanol. However existing levels are still below what would be required at a
commercial scale [5]. With this in mind, the current objective of the DEMA
molecular biology group is the optimisation of these strains to further enhance
ethanol productivity rates. A number of novel strategies are being investigated
including media optimisation, metabolic engineering approaches including several
gene dosage methodologies, enzyme kinetics optimisation and promoter screening.
If successful, these biofuel-producing Synechocystis
PCC 6803 strains have a significant potential to reduce the carbon
footprint while providing a useful solar-generated product.