Enhanced biomass and lipid production of Neochloris oleoabundans under high light conditions by anisotropic nature of light-splitting CaCO3 crystal

Abstract

The aim of this work was to study the anisotropic effect of crystalline CaCO3 nanoparticles (CN)-driven multiple refraction/scattering from the CN-coated agglomerated cells on the rate of photosynthesis and the product yield under high light conditions in the freshwater microalgae Neochloris oleoabundans. The CN-coating via biomineralization significantly improved the biomass and lipid production of N. oleoabundans during second stage of autotrophic induction by sustaining relatively high rate of photosynthesis at high irradiance using the multiple-splitting effect of the anisotropic polymorphism. The CN were successfully produced, adsorbed and grown on the external cells under conditions of mild alkalinity (pH 7.5–8.0), mild CaCl2 concentration (0.05 M) and under nitrogen starvation with strong light (400 µE m−2 s−1). Consequently, lipid content and productivity of N. oleoabundans cells cultured with 0.05 M CaCl2 increased by 18.4% and 31.5%, respectively, compared to the cells cultured with 0.05 M CaCl2 and acetazolamide to inhibit calcification.