Biomass production and biochemical variability of the marine microalga Isochrysis galbana in relation to culture medium

We have studied the autotrophic growth of the marine microalga, Isochrysis galbana Parke, in a batch photobioreactor, comparing five different culture media and analysing the influence of each on growth kinetics as well as on the fatty-acid composition and protein content of the biomass. All the exp eriments were performed at 15 degrees C, with the culture medium at pH 8.0, a specific rate of air supply of 1 vv(-1) min(-1) and a continuous illumin ation of 40-43 W m(-2). The results show no parallel between good nutrition al characteristics and high values of the kinetic parameters. Nevertheless, a compromise between the nutritional factors and growth kinetics could be provided by Ukeles medium, which provided a biomass with a good composition in polyunsaturated fatty acids (quotient n3/n6 = 3.2), an adequate protein content (25.3%) and relatively high values, although not the highest regis tered, for maximum specific growth rate (mu(m) = 0.018 h(-1)) and biomass p roductivity (1.9 x 10(-3) kg m(-3) h(-1)). (C) 2000 Elsevier Science S.A. A ll rights reserved.