Assessing the Effect of Environmental Factors on Production of Microalgae Nannochloropsis Oculata in A Vertical Photo Bioreactor.

Abstract

Background: Microalgae like Nannochloropsis oculata are gaining interest in biotech for sustainable biofuels and nutrition due to their lipid and protein production. This study explores how factors like light, temperature, pH, and nutrients affect N. oculata's growth and productivity to enhance bioprocesses.

Objective: The goal was to refine these environmental conditions to enhance the biotechnological applications of N. oculata , fostering innovative solutions in sustainable energy and nutrition.

Materials and method: This study examined how culture medium, temperature, pH, and light affect biomass, chlorophyll, carotenoids, and lipid content of Nannochloropsis oculata in a photobioreactor. A light intensity of 5000 Lux was used for 16 hours with three medium: Walne, BBM, and Jourdan. Temperatures of 25 °C and 30 °C, and pH levels of 7-9 and 9-11 were tested. Key outcomes included cell density, growth rate, biomass, and lipid production, analyzed using Design Expert.

Results: The study conducted highlighted notable and significant discrepancies in various parameters, specifically cell density (measured in cells.mL^-1), biomass (expressed in g.L^-1), and chlorophyll content across the three different culture media: Walne, BBM, and Jordan. These differences were statistically validated at a significance level of 1%, all while maintaining carefully controlled conditions for temperature and pH. Among the three, Walne medium produced the most favorable outcomes for the growth of N. oculata , particularly when cultured at a pH level of 9 and at a temperature of 25 °C. This medium clearly outperformed the others in terms of biological performance metrics. On the other hand, Jordan medium emerged as the more economically viable option for large-scale cultivation despite the superior biological results associated with Walne. Not only was Jordan medium financially advantageous, but it also demonstrated remarkable lipid production capabilities, with Palmitic acid identified as the predominant fatty acid present in the cultures grown in this medium. Furthermore, the investigation revealed that both temperature and pH have a significant and impactful role in regulating the production of chlorophyll and carotenoids. This finding emphasizes the critical importance of maintaining optimal culture conditions in order to maximize the metabolic production efficiency of microalgae.

Conclusion: In conclusion, the selection of the appropriate culture medium plays a crucial role in influencing both the growth metrics and biochemical performance of N. oculata. Specifically, Walne medium attained the highest measures for cell density, biomass accumulation, and chlorophyll production when cultivated under the optimal conditions of pH 9 and 25 °C. Although Walne medium provides superior biological results, the Jordan medium represents a more cost-effective alternative for large-scale production, thereby underlining the necessity to carefully balance the dual objectives of biological efficiency and economic feasibility within the domain of microalgae cultivation for biotechnological applications. Looking forward, future research endeavors should aim at further optimizing the various media as well as the conditions under which these cultures are grown, with the overarching goal of enhancing both productivity levels and cost-effectiveness in microalgal cultivation processes.