CRISPR and microalgae: A perfect match to enhance natural properties and develop novel strains

Genome editing with CRISPR, a technology that allows precise modification of genetic material, is transforming the field of microalgal biotechnology. It is opening up new possibilities for their optimisation and application, especially in sustainable solutions to environmental challenges.

This cutting-edge technique can be employed to enhance the natural capabilities of microalgae and to develop new strains tailored for specific uses.

For example, CRISPR has been applied to improve the photosynthetic efficiency of microalgae by targeting and removing genes that restrict light absorption or energy transport. In species like Chlamydomonas reinhardtii, the knockout of the CpFTSY gene has reduced the size of chlorophyll antennae, allowing better light penetration in dense cultures. This, in turn, enhances biomass production under high-light conditions. Such an approach is essential for maximising yields in large-scale cultivation systems.

Another major breakthrough is the increase in lipid accumulation, crucial for biofuel production and functional foods. By editing the ZEP gene in Chlamydomonas reinhardtii, researchers have achieved a significant rise in zeaxanthin production, a high-value lipid compound. Similarly, downregulating the CrPEPC1 gene has redirected carbon flow towards lipid biosynthesis, resulting in 94.2% increase in lipid accumulation compared to wild strains.

Stress tolerance has also been significantly enhanced through CRISPR. By optimising genes linked to osmotic and antioxidant regulation, scientists have developed microalgae that can withstand extreme conditions, such as high salinity and oxidative stress. This makes them suitable for cultivation in challenging environments, including wastewater systems.

Moreover, CRISPR enables the modification of genes that govern carbon fixation, improving the efficiency of the Cavin cycle and promoting greater microalgal growth in closed cultivation systems. This not only boosts productivity but also contributes to atmospheric carbon capture, offering environmental benefits.

Finally, genome editing has facilitated the creation of customized microalgae with specific metabolic properties. These strains are capable of producing commercially valuable compounds, such as carotenoids and antioxidants, with application in the pharmaceutical and functional food industries.