Characterization and Analysis of the Exogenous Application of Selected Phytohormones on C. reinhardtii Metabolism

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: auxin, brassinolide, trans-zeatin, and trans-zeatin-riboside. These were systematically introduced to algae at a range of concentrations. Auxin, brassinolide, and trans-zeatin-riboside increased algal growth rates at concentrations of 10-8M to 10-12M. A combination of auxin with trans-zeatin-riboside yielded an increased growth rate of 11%, a specific lipid mass increase of 51%, and, most notably, a lipid concentration increase of 33%. We did not find statistical significance (n=8; p>0.05) in the above changes due to biological variance and human error. However, these findings are consistent in each trial. Therefore, we believe that a treatment of auxin at 10-11M and trans-zeatin-riboside at 10-9M yield practical benefits to biodiesel production.