Higher biomolecules yield in phytoplankton under copper exposure

Area of Science:

• Environmental toxicology
• Microalgal physiology
• Biotechnology

Background:

• Copper is an essential micronutrient for microalgae but becomes toxic at elevated concentrations.
• Industrialization has led to increased copper levels in natural ecosystems.
• Understanding copper's physiological impact on microalgae is crucial for environmental and biotechnological applications.

Purpose of the Study:

• To investigate the physiological responses of Scenedesmus quadricauda to a range of copper (Cu) concentrations.
• To determine the effects of environmentally significant copper levels on microalgal growth, biochemistry, and cell characteristics.
• To explore the potential of copper exposure for enhancing biomolecule production in microalgae.

Main Methods:

• Cultured Scenedesmus quadricauda under controlled conditions with copper concentrations from 0.1 to 25 µM.
• Monitored daily cell density, in vivo chlorophyll a, and photosynthetic quantum yield (Φ_M).
• Quantified free Cu²⁺ ions, cellular Cu, cell volume, carbohydrates, proteins, and lipids after 24-96 hours of exposure.

Main Results:

• Cell abundance and chlorophyll a were significantly affected at copper concentrations of 2.5 µM and above.
• Photosynthetic quantum yield decreased by 31% at the highest copper exposure (25 µM).
• Environmentally relevant copper concentrations (0.5 µM) increased cell volume, while 1.0-2.5 µM enhanced carbohydrate, protein, and lipid yields per cell volume.

Conclusions:

• Copper exposure significantly impacts Scenedesmus quadricauda physiology, with effects varying by concentration.
• Environmentally relevant copper levels can stimulate cell growth and increase the production of valuable biomolecules.
• This study provides insights into copper ecotoxicology and suggests a biotechnological strategy for optimizing microalgal biomass and biomolecule production.