Enhanced production of a lutein-rich acidic environment microalga

Abstract

This study was aimed at increasing productivity of a novel lutein-rich acidic environment microalga, Coccomyxa onubensis, based on efficient inorganic carbon use. Productivity was determined based on dry weight data; inorganic carbon concentration mechanisms were determined by means of carbonic anhydrase activity; carotenoids were extracted with methanol and measured by HPLC techniques. The existence of carbon concentration mechanisms and conditions that might lead to use them for addressing increased productivity of C. onubensis was studied. Best growth and carbon uptake capacity occurred at acidic pH, proving acid-tolerant behaviour of C. onubensis. Incubation in air followed by shift to high carbon conditions enhanced carbon-use efficiency in terms of growth rate and biomass productivity, based on the action of both carbonic anhydrase activities. Lutein accumulated in the microalga at high concentrations above 5-6 g kg(-1) dry weight and did not depend on inorganic carbon conditions. Consequently, repeated cycles of air incubation and high CO2 incubation of C. onubensis might become a suitable tool to perform production processes of lutein-enriched biomass. This study intends to show that acidic environment microalgae can be produced at similar productivities of nonextreme microalgae, with the added advantage of their growth in highly selective culture medium. Particularly, it is applied to C. onubensis which accumulates lutein at commercially relevant concentrations.