Quantifying the competitive advantage of light green algal strains in batch culture

Abstract

Microalgae with truncated light-harvesting antenna (TLA) represent a common strategy employed to enable better light penetration into microalgal culture through the reduction of absorption and consequent wasteful dissipation of excess sunlight. Such strains are often reported to possess enhanced photosynthetic activity on a per chlorophyll basis under high light intensity. By taking into account the light attenuation with culture depth and the difference in chlorophyll content between TLA mutants and wild type, this study attempts to evaluate how the advantage of TLA translates into total photosynthetic yield in a batch process. It was found that the higher photosynthetic rate per cell at low-range light intensities and the greater chlorophyll content seem to give cells with larger light antenna size comparative overall advantage. Growth comparison experiments of a pool of light green Chlamydomonas reinhardtii mutants and a pool of dark green mutants showed that the dark green mutants with larger light antennae size were able to grow faster under conditions of increased cell concentration or culture depth, where the average light intensity was lower. This has implications in low light environments such as large scale microalgal ponds.