Influence of different light wavelengths and carbon sources on energy utilization efficiency by Chromochloris zofingiensis for cell growth and carotenoid synthesis

Abstract

Chromochloris zofingiensis was cultured with different carbon sources (carbonate/glucose/acetate/pyruvate) and light conditions (dark/blue/red) under heterotrophic, autotrophic, and mixotrophic conditions to evaluate its energy utilization efficiency in terms of biomass and carotenoid accumulation. Enhanced specific growth rates of 0.58 d⁻¹ and 0.51 d⁻¹ were observed under blue- and red-light mixotrophic conditions, respectively, which both exceeded the rate of 0.44 d⁻¹ obtained under heterotrophic conditions using a glucose-supplemented medium. The glucose medium showed superior cell synthesis compared to other carbon sources owing to its high utilization. Astaxanthin and neoxanthin accumulation were enhanced under mixotrophic conditions with blue-light. The energy efficiency for the synthesis of new cells was evaluated from a thermodynamic perspective. The efficiency was 1.1 to 2.1 % under autotrophic conditions, while 5.2 to 100 % was observed under heterotrophic conditions. Efficiencies in between were observed under mixotrophic conditions.