Ultraviolet modification of Chlamydomonas reinhardtii for carbon capture

Abstract

Purpose: Carbon dioxide (CO2) levels have been rising rapidly. Algae are single-cell organisms with highly efficient CO2 uptake mechanisms. Algae yield two to ten times more biomass versus terrestrial plants and can grow nearly anywhere. Large scale CO2 sequestration is not yet sustainable due to high amounts of nitrogen (N) and phosphate (P) needed to grow algae in media. Methods: Mutant strains of Chlamydomonas reinhardtii were created using ultraviolet light (2.2-3 K J/m(2)) and natural selection using media with 20\%-80\% lower N and P compared to standard Sueoka's high salt medium. Strains were selected based upon growth in media concentrations varying from 20\% to 80\% less N/P compared to control. Biomass was compared to wild-type control (CC-125) using direct counts, optical density dry weight, and mean doubling time. Results: Mean doubling time was 20 and 25 hours in the low N and N/P strains, respectively (vs 66 hours in control). Using direct counts, growth rates of mutant strains of low N and N/P cultures were not statistically different from control (P=0.37 and 0.70), respectively. Conclusion: Two new strains of algae, as well as wild-type control, were able to grow while using 20\%-40\% less N and P. Ultraviolet light-based modification of algae is an inexpensive and alternative option to genetic engineering techniques. This technique might make larger scale biosequestration possible.