Influence of nutrient availability in Bold’s Basal Medium on growth performance and biochemical productivity of Chlamydomonas reinhardtii

Doman, Khalil M.; Gharieb, Mohamed M.; Abd El-Monem, Ahmed M.; Morsi, Hanaa Hassanein

doi:10.21608/djs.2025.431746.1233

Influence of nutrient availability in Bold’s Basal Medium on growth performance and biochemical productivity of Chlamydomonas reinhardtii

Document Type : Research and Reference

Authors

¹ Botany and Microbiology Department, Faculty of science, Menoufia University.

² Department of Fresh Water and Lakes, National Institute of Oceanography & Fisheries, Cairo, Egypt

10.21608/djs.2025.431746.1233

Abstract

The unicellular green alga Chlamydomonas reinhardtii serves as a model organism for studying physiological and biochemical adaptations of microalgae to nutrient variation. This study investigated the effect of macronutrient modulation nitrogen, phosphorus, and sulfur on the growth, pigment synthesis, and biochemical composition of C. reinhardtii cultivated in Bold’s Basal Medium under sterile and axenic conditions. Cultures were maintained for 30 days, and biomass accumulation, photosynthetic pigments (chlorophyll a, and carotenoids), as well as biochemical constituents (proteins, carbohydrates, phenols, and flavonoids) were quantified. The results demonstrated that C. reinhardtii achieved maximal growth and pigment accumulation at the basal nitrogen (0.25 g/L NaNO₃) and phosphorus (0.175 g/L KH₂PO₄) concentrations, producing a dry weight of 0.061 g/15 mL, chlorophyll a of 15.3 µg/mL, and carotenoids of 6.42 µg/mL. Increasing nitrogen or phosphorus beyond these levels did not enhance productivity. Conversely, moderate sulfur enrichment (0.112 g/L MgSO₄) markedly improved metabolic activity, yielding elevated protein (461 mg/g), carbohydrate (300 mg/g), carotenoid (8.48 µg/mL), and total phenolic (9.17 mg/g) contents compared with the basal sulfur level. Collectively, these findings indicate that C. reinhardtii exhibits nutrient-specific responses: maintaining basal nitrogen and phosphorus levels ensures optimal growth, while sulfur enrichment enhances pigment and secondary metabolite production. This study provides a refined understanding of macronutrient regulation in microalgal metabolism and a framework for optimizing nutrient composition to boost algal growth and biochemical productivity.

Keywords