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

The factors controlling biomass production and the synthesis of astaxa nthin esters in the microalga Haematococcus pluvialis (CCAP34/7) have been investigated using a statistical approach employing response surf ace methodology (RSM). The culture conditions required for optimal gro wth and carotenogenesis in this alga are very different. Of particular importance is the photon flux density: for growth the optimum is 50-6 0 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 lo w levels of NaCl to the medium also stimulates to a small extent synth esis of astaxanthin, but photon flux density remains the overriding fa ctor. The optimal temperature for this strain is quite low at 14-15 de grees C. RSM has been shown to be a rapid and effective technique lead ing to the optimisation of algal culture conditions. This statistical approach can be applied readily to the majority of microalgae and thei r products.