New insights into the stoichiometric regulation of carotenoid production in Chlorella vulgaris

Abstract

Carotenoid accumulation by microalgae has potential for industrial applications. However, the stoichiometric regulation of carotenoid production is not well-understood. Here, the composition and production of major pigments (chlorophyll and total carotenoids) were analyzed in Chlorella vulgaris cultures under different nitrogen (N) to phosphorus (P) molar ratios (0.44–576). The results indicated that carotenoid production in the cultures increased with the increase in P concentrations under N starvation and accumulated effectively when N/P molar ratio was <10.44, indicating that N starvation with high P concentrations may be a promising cultivation strategy for enhancing carotenoid productivity in microalgae. Furthermore, color variance (hue index) of the cultures was associated with the relative chlorophyll and total carotenoid contents. Thus, the carotenoid accumulation due to imbalanced N/P ratios (high P, low N) may explain the yellowish color of the cultures. This study could be instructive for enhancing and monitoring carotenoid productivity in microalgae.