Exploring salinity-induced biochemical changes in Chlorella vulgaris using statistical modelling

Area of Science:

• Environmental Science
• Biotechnology
• Microalgal Physiology

Background:

• Salinity stress is a major abiotic factor affecting microalgal cultivation.
• Understanding Chlorella vulgaris response to salinity is crucial for optimizing biomass production and nutrient removal.

Purpose of the Study:

• To investigate the effects of varying salinity levels on Chlorella vulgaris growth, nutrient uptake, and biochemical composition.
• To determine optimal salinity conditions for microalgal biomass and lipid accumulation.

Main Methods:

• Two-stage cultivation of Chlorella vulgaris under different NaCl concentrations.
• Statistical analysis including Principal Component Analysis (PCA) and Multiple Linear Regression (MLR).
• Biochemical composition analysis (lipids, carbohydrates, pigments).

Main Results:

• 150 mM NaCl resulted in optimal biomass accumulation (978 mg L⁻¹) and high lipid productivity (23.4 mg L⁻¹ d⁻¹).
• Elevated salinity (>300 mM NaCl) led to microalgae mortality.
• Highest lipid (24% DCW) and carbohydrate (32.3% DCW) content observed at 300 mM NaCl.
• PCA and MLR indicated a positive correlation between lipid content, salinity, and exposure time; pigments were sensitive to exposure duration.

Conclusions:

• Moderate salinity (150 mM NaCl) enhances Chlorella vulgaris biomass and lipid productivity without compromising nutrient removal.
• High salinity stress negatively impacts microalgal growth and survival.
• Salinity and exposure time are key factors influencing biochemical composition, particularly lipid accumulation.