Nannochloropsis (Eustigmatophyceae) as source of commercially valuable pigments

Pigment composition and its variation with culture age were analyzed in six strains of Nannochloropsis (Eustigmatophyceae). The capacity for accumulat ion of the ketocarotenoids astaxanthin and canthaxanthin was higher in N. s alina and N. gaditana than in the other strains studied here. The influence of salinity (15 to 100 practical units) on pigment production was studied in N. gaditana, where a defined pattern of variation could not be found apa rt from a notable increase in zeaxanthin at 100 parts per thousand. In cult ures grown in a photobioreactor and at high cell densities of about 10(9) c ells mL(-1), pigment production reached: 350 mg L-1 for chlorophyll a, 50 m g L-1 for violaxanthin, 5 mg L-1 for canthaxanthin, 3 mg L-1 for astaxanthi n. The highest contents of canthaxanthin and astaxanthin obtained in experi ments with N. gaditana were 19.4 and 14.6 ng pigment (10(6) cells)(-1), res pectively, which accounts for 0.7% dry weight. By means of xanthophyll cycl e induction through exposure of cells to high irradiance and at 40 degreesC , conversion of violaxanthin into zeaxanthin may attain up to 70% of the vi olaxanthin content, which corresponds to 0.6% dry weight. The results indic ate that interest in Nannochloropsis as a source of valuable pigments is no t related to its capacity for single pigment accumulation, but the availabi lity of a range of pigments such as chlorophyll a, zeaxanthin, canthaxanthi n and astaxanthin, each with high production levels.