USE OF RESPONSE-SURFACE METHODOLOGY TO OPTIMIZE CAROTENOGENESIS IN THE MICROALGA, HAEMATOCOCCUS-PLUVIALIS

The factors controlling biomass production and the synthesis of astaxanthin esters in the microalga Haematococcus pluvialis (CCAP34/7) have been investigated using a statistical approach employing response surface methodology (RSM). The culture conditions required for optimal growth and carotenogenesis in this alga are very different. Of particular importance is the photon flux density: for growth the optimum is 50-60 mu mol m(-2) s(-1), whereas the optimum for astaxanthin synthesis is much higher at similar to 1600 mu mol m(-2) s(-1). The addition of low levels of NaCl to the medium also stimulates to a small extent synthesis of astaxanthin, but photon flux density remains the overriding factor. The optimal temperature for this strain is quite low at 14-15 degrees C. RSM has been shown to be a rapid and effective technique leading to the optimisation of algal culture conditions. This statistical approach can be applied readily to the majority of microalgae and their products.