Towards genetic improvement of commercially important microalga Haematococcus pluvialis for biotech applications

Haematococcus pluvialis is a unicellular green alga which produces a ketocarotenoid, astaxanthin which has pharmaceutical and nutraceutical applications owing to its high antioxidant activity. Biotechnological approaches such as genetic transformation methods (Agrobacterium-mediated) and cloning strategies, are essential to improve/regulate this ketocarotenoid in Haematococcus. For this studies are necessary to improve Haematococcus through biotechnological means. In this connection, a suitable cocultivation medium for Haematococcus and Agrobacterium tumefaciens was standardized and different antibiotics were screened. Among the cocultivation media viz Z₈, Bold’s Basal Medium, Tris Acetate Phosphate Z₈ with 0.5% mannitol and BBM and Z₈ with half strength LB TAP medium was found suitable for growth of both the alga Haematococcus and Agrobacterium. For the different antibiotics screened to identify the sensitivity of algae, hygromycin at more than 2 mg L⁻¹ showed lethal effect which can be used as a selectable marker gene in genetic transformation, whereas cefotaxime and augmentin showed no effect up to 2,000 mg L⁻¹. The growth of algae was higher in solid selection medium when compared to the liquid selection medium.