Increasing lipid productivity in Chlamydomonas by engineering lipid catabolism using the CRISPR-Cas9 system

Abstract Background Currently, most of the attention in renewable energy industry is focused on the development of alternative, sustainable energy sources. Microalgae are a promising feedstock for biofuel production in response to the energy crisis. The use of metabolic engineering to improve yields of biofuel-related lipid components in microalgae, without affecting cell growth, is now a promising approach to develop more sustainable energy sources and to make this approach more economically feasible. Results The CRISPR-Cas9 system was successfully applied to generate a target-specific knockout of the ELT gene in Chlamydomonas reinhardtii . The target gene encodes an enzyme involved in lipid catabolism, in which the knockout phenotype impacts fatty acid degradation. As a result, the knockout mutants show up to 28.52% increased total lipid accumulation in comparison with the wild-type strain. This is also accompanied by a shift in the fatty acid composition with an increase of up to 27.2% in the C18:1 proportion. These changes do not significantly impact cell growth. Conclusion This study provides useful insights for the improvement of the oleaginous microalgae strain for biodiesel production. The acquired elt mutants showed improved lipid accumulation and productivity without compromising the growth rate.