Unleashing the potential of biotechnological strategies for the sustainable production of microalgal polysaccharides

The prevailing trend toward the increased application of natural polysaccharides in the food, cosmetics, and pharmaceutical sectors has provided the impetus for exploring sustainable biological feedstocks. Amongst them, photoautotrophic microalgae have garnered huge research and commercial interests for polysaccharide production by photosynthesis, thereby concurrently attaining carbon sequestration and green production of valuable metabolites. However, conventional approaches for enhancing polysaccharide accumulation warrant adverse conditions, which in turn hinder cellular growth and productivity. Hence, there exists a pressing demand to harness biotechnological approaches for empowering photosynthetic algae as a sustainable feedstock for polysaccharide production. Meanwhile, it remains an untapped tool for the commercial production of microalgal products, despite the recent advancements in synthetic biology. In this review, we discuss the existing intricacies in polysaccharide biosynthetic circuits and propose crucial strategies to circumvent those techno-biological complexities. We also highlight the possible approaches to circumventing such limitations to successfully employ metabolic engineering for the large-scale production of microalgal polysaccharides. The technologically feasible directions for unleashing the biotechnological potential of microalgae as green cell factories are projected toward the sustainable biosynthesis of polysaccharides.