The unexplored metabolic potential of Chlamydomonas mutants for faster growth

Despite decades of research with the green alga Chlamydomonas reinhardtii as an established model organism, the role of growth rate limitations within this system has been only partly illustrated. A deeper understanding may be gained by exploring the potential changes in growth rates among a wide library of C. reinhardtii mutants, particularly in those with metabolic related mutations. Through a large-scale multiplexed reverse-genetics screening of the Chlamydomonas library of mutants (CLiP), we were able to identify 13 potentially fast-growing strains, with metabolic related mutations. Following their growth characterization as monocultures, 5 of the mutants showed a significantly higher growth rate compared to wild type (CC-5325), reaching up to 80% faster growth. Additionally, each potential mutant strain has been photosynthetically characterized and compared to the others and to the WT, which allowed us to ascertain differences between the mutant strains photosynthetic systems and the possible effects of each specific mutation on their activity. Metabolomic exploration of these mutant strains through ¹³CO₂-labelling-based flux analysis and metabolic engineering is expected to assist in evaluating the correlation between growth rates, photosynthetic and metabolic activity, and the specific mutations, shedding light on the mechanisms supporting faster growth rates of photosynthetic cells and holding promise for improved algal biomass accumulation. In an era where many are seeking ways to increase biomass production for feed and energy goals, the importance of such insights cannot be overestimated.