Isolation of Astaxanthin-Producing Microalgae and Potential Biotechnological Applications

Background: Astaxanthin (AXA) has recently attracted considerable attention for its biological properties such as antioxidant, anti-inflammation, and anti-cancer activities, as well as a coloring activity to fish. Astaxanthin is found in several bacteria, yeast, and microalgae, and they are thought as primary producers of AXA. Since microalgae generally can grow under photoautotrophic condition, AXA production using microalgae is thought cost effective in comparison to bacteria and yeast. Methods: In this paper, efforts on improvement of AXA productivity using known microalgae including H. pluvialis as well as isolation of a novel AXA-producing strain are reviewed. Results: While Haematococcus pluvialis has been extensively studied among microalgae, mass production of the strain still possess technological issues derived from slow-growing property of the strain. Considering that the most of microalgae in natural environments remain to be cultivated, isolation and characterization of novel AXAproducing strains seems to contribute to an expansion of microalgal AXA market. Actually, several AXA-producing strains, including Monoraphidium sp. GK12 (hereafter GK12), have newly been reported thus far and studied their potential to application in industries. Conclusion: While there are some results which seem promising for expansion of microalgal AXA market, further exploration of novel AXA-producing strains as well as improvement of culture conditions for known strains seems necessary.