The impact of temperature and pH on lipid production of seasonally bioprospected microalgae

Abstract

Microalgae produce economically valuable metabolites that can be used in the renewable energy and biopharmaceutical industries. In particular, microalgae have been identified as promising lipid producers, where total quantities and profiles can be enhanced by subjecting microalgal cells to stress conditions such as temperature and pH. However, while cultivation conditions can influence the feasibility of mass production of microalgae, harvesting them from their growth medium remains a significant economic hurdle. Therefore, this thesis initially presents a literature review of available harvesting methods and their associated costs. The review is followed by a study on bioprospected microalgae from various industrially impacted aquatic environments. The thesis also examines factors impacting lipid production on microalgae bioprospected over a year and investigates the effect of exposure to variations in temperature and pH culture conditions. The impacts on growth rate, total lipid accumulation and lipid profiles were determined. It was found that changes in temperature affected microalgal biomass and lipid production more than changes in pH. However, the samples' lipid profiles varied significantly as a function of both temperature and pH. Therefore, the economical production of biofuels using microalgae requires a careful selection of strains to match growth conditions to enhance productivity.