Showing papers on "Chlorococcum published in 1997"

Composition and accumulation of secondary carotenoids in Chlorococcum sp.

Abstract: A locally isolated Chlorococcum sp. could accumulate astaxanthin and its esters as secondary carotenoids. The secondary carotenoids could reach a concentration of 5.2 mg g−1 d. wt, and were located in the cytoplasm and chloroplast as globules. Cells grew best at pH 8.0 and 30 °C, at which the growth rate was about 0.066 h−1. Acidic condition (pH 5.5 and 6.5) and slightly elevated temperature (35 °C) enhanced the cellular accumulation of astaxanthin. Outdoor studies indicated that Chlorococcum sp. grew well in a tubular photobioreactor. In medium containing 2 mM and 10 mM NH4CI, the cellular contents of total secondary carotenoids and astaxanthin reached similar levels (5.0 mg g−1 d. wt and 2.0 mg g−1 d. wt, respectively) in the 15 days of cultivation, while the yield of total secondary carotenoids and astaxanthin in 10 mM NH4CI were higher (45 mg L−1 and 18 mg L−1, respectively). The advantages of tolerance to high temperature and extreme pH values, relative fast growth rate and ease of cultivation in outdoor system suggest that Chlorococcum sp. could be a potential candidate for mass production of secondary carotenoids in particular astaxanthin.

Enhanced accumulation of secondary carotenoids in a mutant of the green alga, Chlorococcum sp.

Abstract: A colour mutant of the unicellular green alga Chlorococcum sp. was obtained by visual colour detection method on plates with medium containing sodium azide. The growth of the mutant MA-1 was more susceptible to azide compared with the wild type, whereas the total secondary carotenoid (SC)synthesis was more resistant to the inhibitor. The azide concentration that inhibited SC formation by 50% (I50) was ten times higher than that required for the wild type. The mutant was stable over several consecutive subculturings in the absence of azide. The indoor and outdoor studies showed that the mutant could synthesise more than 2-fold of the total SC and astaxanthin of the wild type. The mutant MA-1 could be a natural source of SC and astaxanthin.