The photosynthetic microalga Haematococcus pluvialis is a potential source of astaxanthin, which is used as a feed additive, to enhance the pigmentation of cultured salmon and egg yolks, and also as an antioxidative drug ( 1). A morphological change in H. pluvialis from green vegetative cells moving with flagella to red resting cyst cells without flagella is accompanied by an enhancement in astaxanthin production. This morphological change can be induced under conditions of stress, such as high temperature, nutrient deficiency ( 2) and a high light intensity ( 3).