(772a) Development of a Thermoreversible Medium to Culture and Efficiently Harvest Microalgae

With the ability to generate different types of biofuels and a variety of valuable chemicals, microalgae represent a promising alternative to fossil fuels. However, the development of high throughput cultivation and efficient harvesting techonologies is necessary to make microalgal biomass production a more viable option. Herein, a new Tris-Acetate-Phosphate-Pluronic (TAPP) medium with thermoreversible sol-gel transition properties developed for cultivation and efficient harvesting of microalgae will be presented.

This sol-gel transition phenomenon refers to the transformation from a low-viscosity fluid to an elastic solid upon heating. For the TAPP medium developed, this gelation process is completely reversible upon cooling. The thermo-rheological properties of the new pluronic-based medium as well as the resulting pluronic-microalgae matrix after cultivation are systematically characterized. moreover, a framework is proposed to efficiently harvest the microalgal biomass produced through small variations of temperature.

Microalga Chlamydomonas reinhardtii is successfully cultivated in the new TAPP medium and leads to equivalent production of microalgal biomass with similar lipid and carbohydrate composition than that obtained from cultivation in the traditional TAP medium. The harvesting process of the microalgal biomass produced is also highly simplified with the TAPP system. In fact, confinement of microalgal cells in the pluronic matrix leads to a cluster distribution that increases the settling velocity by a factor of ten. Through small variations of temperature, microalgae are allowed to settle, the broth subsequently jellified and ninety percent of microalgal biomass are harvested simply through scrapping off the surface.

The implications of this new cultivation and harvesting technology as well as the potential for varieties of large scale applications will be discussed.