Storage Compound Accumulation in Diatoms as Response to Elevated CO₂ Concentration

• Main Authors: Erik L. Jensen, Karen Yangüez, Frédéric Carrière, Brigitte Gontero
• Format: Article
• Language: English
• Published: MDPI AG 2019-12-01
• Series: Biology
• Subjects: co₂; chrysolaminarin; diatoms; triacylglycerol
• Online Access: https://www.mdpi.com/2079-7737/9/1/5

Accumulation of reserve compounds (i.e., lipids and chrysolaminarin) in diatoms depends on the environmental conditions, and is often triggered by stress conditions, such as nutrient limitation. Manipulation of CO₂ supply can also be used to improve both lipids and carbohydrates accumulation. Given the high diversity among diatoms, we studied the two marine model diatoms&#8212;<i>Thalassiosira pseudonana</i> and <i>Phaeodactylum tricornutum</i>, a freshwater diatom, <i>Asterionella formosa</i>, and <i>Navicula pelliculosa</i>&#8212;found in fresh- and sea-water environments. We measured the accumulation of reserve compounds and the activity of enzymes involved in carbon metabolism in these diatoms grown at high and atmospheric CO₂. We observed that biomass and lipid accumulation in cells grown at high CO₂ differ among the diatoms. Lipid accumulation increased only in <i>P. tricornutum</i> and <i>N. pelliculosa</i> grown in seawater in response to elevated CO₂. Moreover, accumulation of lipids was also accompanied by an increased activity of the enzymes tested. However, lipid accumulation and enzyme activity decreased in <i>N. pelliculosa</i> cultured in fresh water. Chrysolaminarin accumulation was also affected by CO₂ concentration; however, there was no clear relation with lipids accumulation. Our results are relevant to understand better the ecological role of the environment in the diatom adaptation to CO₂ and the mechanisms underpinning the production of storage compounds considering diatom diversity.