Characterization and analysis of the exogenous application of selected phytohormones on C. reinhardtii metabolism

Abstract

Introduction of algal biofuel on an industrial scale will only be possible if production cost can be lowered, either by speeding algal growth, increasing lipid production per cell, or both. Our approach examined the application of phytohormones to algae to reach this goal. Bioinformatics and literature led us to four phytohormones: Indole-3-acetic acid, Epibrassinolide, Trans-zeatin, and Trans-zeatin-riboside. These were systematically introduced to algae at a range of concentrations. IAA, Epibrassinolide, and Trans-zeatin-riboside increased algae growth rates at concentrations of 10-8M to 10-12M. A treatment of Trans-zeatin-riboside yielded an increase in growth rate of 31.1 ± 9.4% (p < 0.05, n=8), an increase in algal dry mass by 38.9 ± 11.9% (p < 0.05, n=8), a negligable change in specific lipid mass (p < 0.05, n=8), and, most notably, a lipid concentration increase of 44.6 ± 42.1% (p < 0.05, n=8). A treatment of Trans-zeatin-riboside at 10-11 M yields practical benefits to biodiesel production.