Effect of light intensity and ammonium-N on carotenogenesis of Trentepohlia odorata and Dunaliella bardawil

Abstract

Axenic Trentepohlia odorata was cultured at three different NH4Cl levels (3.5 × 10-2, 3.5 × 10-3, 3.5 × 10-4 M) and three different light intensities (48, 76, 122 μmol m-2 s-1). Chloride had no effect on growth over this range of concentration. High light intensity and high NH4Cl concentration enhanced the specific growth rate. The carotenoid content increased under a combination of high light intensity and low N concentration. When D. bardawil was exposed to the same combination of growth conditions, there was an increase in its carotenoid content. The light saturation and the light inhibition constants (Ks and Ki, respectively) for growth, and the saturation constant (Km) for NH4Cl were determined. The Ks and Ki values were higher in T. odorata (66.7 and> 122 σmol m-2 s-1, respectively) than in D. bardawil (5.1 and 14.7 μmol m-2 s-1, respectively). The Km value determined at 122 μmol m-2 s-1, however, was lower in T. odorata (0.048 μM) than in D. bardawil (0.062 μM). © 1993 Kluwer Academic Publishers.