The Biobrio 12(3&4), 2025

Role of sodium chloride concentration in modulating biomass productivity and lipid dynamics in Chlorella vulgaris.

Madhu Muskan & Kanchan Kumari

ABSTRACT:

Salinity is a crucial abiotic regulator of microalgal metabolism that determines productivity, pigment synthesis, and biochemical allocation. The present study investigates the physiological and biochemical responses of Chlorella vulgaris under varying sodium chloride (NaCl) concentrations - representing deficiency (0 mM), optimal control (100 mM), and abundance (200-400 mM) - over a 14-day growth cycle. Biomass productivity, lipid accumulation, and total chlorophyll concentration were quantified periodically to evaluate growth kinetics and stress-induced metabolic transitions. Sigmoidal growth trends indicated that optimal NaCl (100 mM) produced the highest biomass (1.58 g/L) and pigment concentration (11.7 mg/L), while elevated salinity (≥ 300 mM) significantly reduced growth but enhanced lipid accumulation (up to 47.8%). ANOVA confirmed statistically significant (p < 0.05) variation among treatments, and correlation analysis revealed strong negative associations between lipid content and both biomass (r =-0.93) and chlorophyll (r = -0.88). FTIR spectral analysis exhibited stress-responsive shifts in amide I (1650 → 1642 cm-¹) and enhancement of ester carbonyl bands (1743 cm-¹), validating peptide denaturation and triacylglycerol enrichment under salinity. These results confirm that moderate salinity promotes balanced growth, while controlled salt stress strategically induces lipid biosynthesis in C. vulgaris, offering a sustainable approach for biofuel and bioproduct optimization.

Keywords:    

Chlorella vulgaris, NaCl stress, lipid productivity, chlorophyll degradation, biomass kinetics, FTIR analysis, salinity adaptation.

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