BIOTECHNOLOGY

Turning Schizochytrium into a Biofactory for Astaxanthin: A Breakthrough in Biotechnology

China, 16 May 2025 | A team of researchers has boosted astaxanthin production in this microalga by an astonishing 169 times

microalga-schizochytrium

Scientists at the Tiajin Institute of Industrial Biotechnology, part of the Chinese Academy of Sciences, have successfully engineered the microalga Schizochytrium sp into an efficient biological factory for producing astaxanthin-a powerful antioxidant carotenoid with high demand across the food, cosmetics, health and aquaculture industries.

Through a multi-pronged biotechnological approach-combining electroporation-induced mutagenesis, genetic engineering, subcellular enzyme targeting, and fermentation optimization-the team achieved a record yield of 29.5 mg/L of astaxanthin in bioreactor conditions. This represents a 169-fold increase compared to the wild-type strain.

This research, published in the Chemical Engineering Journal, focused on developing a mutant strain named Schizochytrium sp AST32, created by applying high-voltage electric pulses to trigger random genetic mutations. This strain showed an increase in astaxanthin content form 7.56 μg/g to 55.17 μg/g.

Building on this, the scientists overexpressed five key carotenoid biosynthesis genes (idi, crtE, crtIBY, crtZ, and crtW), raising the content further to 374.85 μg/g. By directing these enzymes specifically to lipid bodies within the cells using a fusion protein (PLIN), they ultimately achieved an intracellular concentration of 400.38 μg/g.

Fermentation was then scaled up in a 5-litre bioreactor, employing a glucose-limitation strategy to maximise output. This resulted in a peak production of 29.5 mg/L of astaxanthin, along with 3.83 g/L of DHA, which accounted for 45% of total lipid content.

“This study lays the groundwork for commercial-scale production of astaxanthin through microbial biosysnthesis using Schizochytrium sp, offering a promising alternative to traditional sources,” the authors conclude.