CRISPR-Cas9 genome editing in microalgae for improved high-value products (HVP) production

Microalgae are a broad class of photosynthetic, eukaryotic microorganisms that transform carbon dioxide and solar energy into high-value products (HVPs), which have significant commercial value. They are viewed as promising platforms for HVP production. With the global population estimated to reach approximately 9.22 billion by 2075, microalgae are recognised for their resilient and remarkably effective biofactories. However, despite their industrial relevance and environmental advantages over land plants, microalgae-based HVP production requires further optimisation to become commercially viable. Hence, genome editing tools such as clustered regularly interspaced short palindromic repeats/Cas protein 9 (CRISPR-Cas9) are a potential strategy to generate microalgae strains that promote the production of HVP more efficiently to meet industrial demand compared to other genome editing techniques such as zinc finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs). This review paper examines the potential and effectiveness of CRISPR-Cas9 in microalgae for enhancing the production of HVP, particularly PUFA, carotenoids, mycosporine-like amino acids, and vitamins. The literature search used online databases to consider the inclusion and exclusion criteria. In conclusion, due to its effectiveness, CRISPR-Cas9 is recognised as the most widely used genome editing technique for enhancing microalgae HVP production.