Date of Award
Doctor of Philosophy (PhD)
Cyanobacteria are oxygenic phototrophs with great potential as hosts for renewable fuel and chemical production. They grow very quickly (compared with plants) and can use sunlight for energy and CO2 as a carbon source (unlike yeast or E. coli). While cyanobacteria have been engineered to make many chemicals that are native and non-native parts of their metabolism, this work is concerned with the production of heptadecane in Synechocystis sp. PCC 6803. Heptadecane is in a class of natural products produced by all cyanobacteria, but in quantities insufficient for industrialization. Towards this future goal, we have built enabling systems for the overproduction of fuels and chemicals in Synechocystis 6803 and cyanoabacteria generally. These tools include plasmid vectors for the overproduction of heterologous proteins and genome- scale metabolic models that can predict strategies for metabolite overproduction. We have shown that the vectors we developed are helpful in controlling the level and timing of heterologous protein expression using a fluorescent reporter, and have made progress towards heptadecane overproduction. During this process, we have also found that heptadecane is crucial for cold tolerance and modulates cyclic electron flow in photosynthesis. In addition to measuring this phenotype in vivo, we have analyzed it in silico using our genome-scale metabolic model and have gained insight into the role of cyclic electron flow in photosynthesis generally.
Robert Blankenship, Cynthia Lo, Fuzhong Zhang