An Enhanced and Sustainable Algal Biomass to Third-Generation Biofuel Conversion System

Algae are one of the most promising sources of bio-fuels due to their environmental sustainability and the direct use of their lipids as fuels. Traditional methods of extracting these lipids, however, prevent the use of algal biofuels from being a commercially viable option. Moreover, naturally-occurring and uncontrollable algae blooms create innumerable quantities of ocean dead zones. These sizeable hypoxic and anoxic areas create devastating measures to the marine ecosystem, as well as ocean-related industries.  This project combines engineering with biotechnology to create a system that solves both of these problems.  It was hypothesized that excess, harmful algae can be used for efficient biofuel conversion. Algae scrubbers – panels of fast-growing macro algae – are used to consume excess growth stimulants from waste water pollution. Some of these include nitrates, nitrites, and ammonia, which are all contributors to the emergence of dead zones. As the wastewater is being filtered in the river by the panels, the rapid growth of algae will generate a source of excess biomass. Unfortunately, research today is limited by the inefficient conversion of algae biomass to biofuel; however, this project introduces a novel technique that cuts costs of biofuel extraction through genetically modifying algae. As opposed to conventional hexane extractions that break the cell wall, thereby killing the algae, gene modifications of acyl-acp synthetase (Δaas) and thioesterase (‘tesA) allow for automatic excretion of lipids. In addition to automatic excretion, lipid production itself is also optimized. When the algae scrubber system was tested, it was found that the nitrate levels in the water was nearly cut in half from 80 ppm to 45 ppm. After the biomass was genetically altered, the knockout of Δaas yielded 44.90 mg/L and the Δaas ‘tesA culture yielded 33.15mg/L of lipids. As hypothesized, cell functions were not inhibited by the transformation; therefore, a single culture of algae was able to continually produce lipids as opposed to the re-culturing necessary in traditional methods This brings the algae scrubber culture on par with the biofuel demand; each culture of algae holds millions of lipid-excreting cells. Furthermore, the modifications of Δaas and ‘tesA, in light of possible contamination with wild cultures, produce no toxic side effects. Emissions tests were conducted on biofuel/fossil fuel mixtures for a vision of a smooth transition from petroleum to biofuels. It was found that as the percentage of biofuel increased, the harmful emissions causing air pollution decreased. Albeit human intervention will be needed to collect and alter the cultures, the benefits of the system outweigh its few burdens.  Although it will take more years of experimentation to optimize this system, this project validates its plausibility on par with the increasing demands for environmental protection and alternative energy.