Storage Compound Accumulation in Diatoms as Response to Elevated CO₂ Concentration

Area of Science:

• Marine biology
• Phycology
• Biochemistry

Background:

• Diatom reserve compound accumulation (lipids, chrysolaminarin) is influenced by environmental stress, like nutrient limitation.
• Carbon dioxide (CO2) levels can be manipulated to enhance lipid and carbohydrate production in diatoms.

Purpose of the Study:

• To investigate how varying CO2 concentrations affect reserve compound accumulation in diverse diatom species.
• To examine the activity of carbon metabolism enzymes in response to different CO2 levels across various aquatic environments.

Main Methods:

• Cultured four diatom species (Thalassiosira pseudonana, Phaeodactylum tricornutum, Asterionella formosa, Navicula pelliculosa) in freshwater and seawater.
• Exposed cultures to high and atmospheric CO2 concentrations.
• Measured biomass, lipid, and chrysolaminarin accumulation, alongside key enzyme activities involved in carbon metabolism.

Main Results:

• Biomass and lipid accumulation varied significantly among diatom species under elevated CO2.
• Lipid accumulation increased in Phaeodactylum tricornutum and Navicula pelliculosa in seawater with high CO2, accompanied by higher enzyme activity.
• In contrast, Navicula pelliculosa in freshwater showed decreased lipid accumulation and enzyme activity at high CO2.

Conclusions:

• Diatom adaptation to CO2 levels and storage compound production mechanisms are species- and environment-specific.
• Environmental factors play a crucial role in modulating diatom responses to altered CO2 concentrations.