UC Riverside

This work supports the production of food, fuel, and other bio-based products from single-celled organisms, or organisms grown in suspension, with the goal of reducing our environmental impact by minimizing our dependence on fossil fuels and resource intensive agriculture. I address three major bottlenecks currently limiting the bioeconomy. Biological photosynthesis, which is inefficient at converting solar energy into biomass, limits food production as well as many downstream processes that rely on plant products, like fermentation which relies on sugar. Our artificial photosynthetic technology addresses this by eliminating the need for biological photosynthesis in food production. Acetate produced from carbon dioxide and electricity, through electrochemical catalysis, is used to cultivate organisms heterotrophically, for an overall process that is substantially more solar-to-biomass energy-conversion efficient than biological photosynthesis. Typically, heterotrophic growth is reliant upon biological photosynthesis for a source of carbon and energy, including sugar from plants or petroleum, a product of ancient photosynthesis. To confront this, I explored the potential of acetate as a carbon and energy source for the cultivation of plant cell cultures. By establishing the current limitations, investigating the metabolism, and quantifying expression of important genes, I set the groundwork to eventually cultivate plant cell cultures independent from industrial agriculture, perhaps within our artificial photosynthetic system. The third bottleneck addressed in this work is plant and algal lipid metabolism, which is yet to be fully understood and limits the production of fuel and other lipid-based products. I used a high-throughput, forward genetic, genome-wide mutant screen in a model green algal species to identify genes important for lipid accumulation in response to nitrogen deprivation. The three projects described in this thesis aim to address the sustainable production of important products we rely on and use daily. This work can be built upon to innovate and move away from fossil fuels and inefficient industrial agricultural practices, for the benefit of our planet and future generations.