Biochemical and Morphological Characterization of Heterotrophic <i>Crypthecodinium cohnii</i> and <i>Chlorella vulgaris</i> Cell Walls

Abstract

Microalgae are attractive for the food and cosmetic industries because of their nutrient composition. However, the bioaccessibility and extractability of nutrients in microalgae are limited by the rigid and indigestible cell wall. The goal of this study is to explore the cell wall polysaccharides (CWPSs) composition and morphology in heterotrophic <i>Crypthecodinium cohnii</i> and <i>Chlorella vulgaris</i> biomasses during growth. Our results showed that glucose was the major component of CWPSs and exopolysaccharides in <i>C. cohnii</i>. <i>C. vulgaris</i> CWPSs have a similar sugar profile in exponential and stationary phases, essentially composed of rhamnose and galactose. <i>C. vulgaris</i> cell wall thickness increased from 82 nm in the exponential phase to 114 nm in the stationary phase and consisted of two main layers. <i>C. cohnii's</i> cell wall was 133 nm thick and composed of several membranes surrounding thecal plates. Understanding of the microalgae cell wall helps developing a more efficient and targeted biorefinery approach.