Investigating the Effect of Salinity and Nitrogen on Growth and Lipid Production in Microalgae Chlorella vulgaris EP 33 by Response Surface Methodology

Subject Areas : microalgae

Samira Saeidi Akbarzadeh ¹ , Elaheh Pourfakhraei ^{2 *} , Mohsen Zargar ³ , Seyed Soheil Aghaei ⁴ , Farhad Jadidi ⁵

1 - Department of Microbiology, Qom branch, Islamic Azad University, Qom, Iran,
2 - Industrial and Environmental Biotechnology Department, Research Institute of Applied Science, ACECR, Shahid Beheshti University, Tehran, Iran,
3 - Production and Recycling of Materials and Energy Research Center, Qom branch, Islamic Azad University, Qom, Iran,
4 - Production and Recycling of Materials and Energy Research Center, Qom branch, Islamic Azad University, Qom, Iran
5 - Industrial and Environmental Biotechnology Department, Research Institute of Applied Science, ACECR, Shahid Beheshti University, Tehran, Iran

Received: 2023-12-20 Accepted : 2025-03-11 Published : 2024-06-21

Keywords: Chlorella vulgaris EP33 , Nitrogen , Optimization with response surface methodology , Salinity,

Abstract :

It is important to increase lipid content to use it in food supplements and biodiesel. Changing the concentration of salinity and nitrogen is one of the important and practical strategies in this direction. Chlorella vulgaris EP33 microalga, isolated and identified from the waters of the northern regions of Iran (Mazandaran province), can be used as a lipid source. This study uses a central composite design in Response Surface Methodology, including 3 replications at the central point and 11 experiments to optimize lipid accumulation. Lipid content was measured after 14 days, in culture conditions at 30°C, light intensity 2000 lux, pH 7 and 16/8 dark and light. The results showed that the highest lipid content was obtained in the optimal conditions of nitrogen 10 and salinity 115 mM (0.503 g/g dry biomass) and the growth rate in these conditions was half of the optimal conditions in nitrogen 10 and zero salinity. The experimental values and the values predicted by the software also had logical relationships, which indicated the appropriateness of the used models as well as the compatibility of the Response Surface Methodology to determine the optimal conditions. Changing the concentration of some effective factors in lipid production, can be used for economic optimization of lipid production with practical purposes. In this study, it was observed that nitrogen supply increases the tolerance level of microalgae to salinity as a practical way to increase lipid production. The results of optimization of process variables through response surface methodology reflect the leading research towards increasing lipid content using an economically efficient technological approach.

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