Incorporation of chemical modulators to enhance algal biomass and bioproduct synthesis

To minimize the cost of algae-based biofuels and bioproducts, boosting biomass productivity and enhancing the stability of cultures in outdoor cultivation systems are imperative. Strain improvement strategies, mainly adaptive evolution, random mutagenesis, and genetic engineering, focus on perturbing the metabolism of algae to develop desired phenotypes. However, the aforementioned techniques are time- and labor-intensive with a possibility of reversion of the mutated/ adapted phenotypes back to wild type. In this regard, the chemical genetics approach has emerged as a rapid and powerful approach to preferentially direct the metabolism of algae towards desired target products with the incorporation of small chemical modulators in a dosedependent manner. In this review, we critically asses the use of chemical modulators to tweak the metabolism of several algal species and enhance biomass production, bioproduct yield, and resilience to abiotic stressors. The review highlights important categories of chemical modulators and the techniques employed to identify and screen such small effective molecules. Chemical modulators enable the re-design and fine-tuning of targeted algal metabolic pathways rendering chemical genetics a promising approach for enhancing algal productivity particularly in largescale cultivation.