Lipid accumulation in mixed photoautotrophic cultures from municipal wastewater

Abstract

The growing consumption and need for sustainable forms of energy has spurred interest in biofuels and the feedstocks that offer possible solutions. Microalgae have emerged as a possible resource for the more sustainable production of biomass and biofuel, but nutrient and water demands offer challenges that limit large-scale biomass and biofuel production. Wastewater offers a potential solution to this issue as a low-quality but high-nutrient water source that could be exploited for the production of microalgal biomass. Many studies have successfully isolated or introduced algal monocultures into a wastewater environment for either lipid production or bioremediation purposes. However, recent studies have indicated increased lipid yields and nutrient removal with mixed cultures and algal consortia, but further work is needed to understand community dynamics and population networks that increase the niche landscape with compensatory interactions that promote desired functions (e.g., biomass and/or lipids) in a stable manner. This thesis seeks to explore the potential of a mixed photoautotrophic population that is currently being used to treat municipal wastewater (i.e., nutrient removal) for lipid producing capabilities and the impact of indigenous bacterial populations native to wastewater. In doing so we hoped to test the effects of increased biodiversity on lipid production at an interspecific level. Community dynamics, lipid profiles, and biomass productivities were monitored over a series of growth experiments utilizing filter-sterilized and non-sterile wastewater. The results from these experiments indicated substantial lipid production from communities grown in the presence of indigenous bacterial communities found in wastewater. These results suggest the prospect that wastewater possesses for biofuel production with mixed algal communities. It also indicates a more dynamic role of in situ community interactions in contributing to biomass and bio-oil accumulation of mixed algal communities.