The feasibility of mixotrophic culture of high selenium-enriched Spirulina platensis was investigated in this study. The results indicated that supplementation of acetate to the mixotrophic culture of S. platensis led to a significant enhancement in biomass concentration, chlorophyll a, lutein, P-carotene, phycocyanin and allophycocyanin production when compared to the photoautotrophic culture. Stepwise addition of selenium (Se) source during the exponential growth phase of S. platensis can avoid the inhibitory effect of high Se concentration on cell growth. At an accumulative Se concentration of 450 nng L-1 under mixotrophic culture conditions, the highest Se yield was obtained; while significant enhancement in Se accumulation capability, algal biomass concentration and photosynthetic pigment yield was also observed. These results indicated that the application of mixotrophic culture with stepwise addition of Se to culture of S. platensis offers a more effective and economical way for the production of high Se-enriched biological compounds. (c) 2005 Elsevier Inc. All rights reserved.