THE CHEMICAL-COMPOSITION OF CHAETOCEROS SP (BACILLARIOPHYCEAE) UNDER DIFFERENT LIGHT CONDITIONS

Chaetoceros sp. growth with white, pure blue and mixed blue light in 1 0-1 semicontinuous culture with 50% daily dilutions was light-limited at photon flux densities of 199 mu mol m(-2) s(-1). At the above light level the type of light did not cause variations in protein content, but the use of mixed blue (192.5 mu mol m(-2) s(-1) of blue, and 6.5 o f white, light) caused an important decrease in carbohydrates and an i ncrease in lipids. Chlorophyll a was higher in blue than in white ligh t. Increasing photon flux densities increased biomass production. In w hite light photoinhibition occurred earlier than in blue light (>498 a nd 565 mu mol m(-2) s(-1), respectively). The highest cell densities w ere in white light, but the highest yields in biomass (mg l(-1)) were in mixed blue, due to the higher mean cell weight. There were no diffe rences in chlorophyll content. The proximate composition of the biomas s produced at saturating photon fluxes did not change considerably in white light. Both types of blue caused an increase in proteins but the alternative carbon sinks were lipids in mixed blue and carbohydrates in pure blue light. Methionine was highest in mixed blue and there wer e no other important differences in amino acid profiles. 18C fatty aci ds were greater than 24% in pure blue and less than 5% in white and mi xed blue. The unsaturate 18:1 (oleic acid) was more than 15% of the to tal fatty acids in pure blue, which might have important effects on th e dietary value of the biomass produced.