Genetic, physiological and biotechnological assessment of microorganisms for renewable and sustainable energy resource production

Official URL: http://risc01.sabanciuniv.edu/record=b1589825 (Table of Contents)

The term "algae" defines variety of photosynthetic organisms found throughout the world in various environmental conditions. Algae species are estimated to number in the tens of thousands. Because algae are photosynthetic, naturally able to replicate rapidly and produce high amount of oils, alcohols, and biomass, they have attracted the attention of researchers and industrial producers seeking alternatives to currently used fossil fuels. Algae thrive on organic carbon or CO2, nutrients such as nitrogen, phosphorus and other inorganic substances which enables algae to be used in bioremediation. Growth conditions, nutrients such as carbon and nitrogen, and many other factors affect the algal cell metabolism. Thus, manipulation of different cultivation conditions have been shown successful in increasing algal biomass and lipid productivity in order to substitute petroleum use. Algae biotechnology research goals especially include finding ways to increase the reproductive rate, improve metabolism of inputs, and enhance the production of desired oils, fuel-grade alcohols in useful species. In this thesis, newly isolated halophilic unicellular green algae species are assessed for potential renewable energy resource. Novel strategies for increasing cellular lipid production were established. Exogenous application of oxidative stress by hydrogen peroxide treatment was shown as a novel lipid accumulation inducer. Moreover, increased lipid accumulation response was also observed in heavy metal induced oxidative stress which makes combination of heavy metal bioremediation and oil production possible as a novel algae cultivation strategy. Directed evolution and natural selection strategies were applied to model organism Saccharomyces cerevisiae and Dunaliella salina for revealing underlying biochemical, genetic factors of increased cellular lipid production in order to provide useful strategies for future biofuel production.