EVALUATING ENVIRONMENTAL STRESSORS TO BOOST MICROALGAL LIPID AND BIOMASS YIELD: A COMPREHENSIVE ANALYSIS FOR SUSTAINABLE ENERGY GENERATION

Abstract

Understanding how environmental factors influence microalgal biomass and lipid productivity is essential for advancing sustainable bioresource development. The marine microalga Gonyostomum sp., grown in Conway medium, was used in this study to evaluate the biomass and lipid yield under varying photoperiod, salinity and pH conditions using response surface methodology (RSM) with a Box-Behnken design. The conditions for the control culture are 24 ± 1 °C, constant light (24 h) at 150 μEm⁻²s⁻¹, 8 ppt salinity, pH 7.3 ± 0.1, and mild aeration (4.53 ± 0.53 mgL-1). Seventeen experimental runs were conducted to determine optimal conditions within the tested ranges of parameters: 12 - 20 h photoperiod, 3 - 13 ppt salinity, and 6.5 - 8.5 pH. The results showed that a combination of 15.81 hour (15hour 48 min) photoperiod, 8.50 salinity and 6.86 pH produced the maximum biomass (1.78 gL-1) and lipid content (82.35%) whereas control combination produced 0.55 g L⁻¹ biomass and 27% lipid. Gas chromatography (GC) analysis of the fatty acid composition showed a profile that was highly favorable for biofuel applications: 63.721% monounsaturated fatty acids (MUFA), 9.99% polyunsaturated fatty acids (PUFA), and 26.282% saturated fatty acids (SAFA), with the predominant constituents being oleic acid (58.955%) and palmitic acid (23.614%). Gonyostomum sp. has the potential to be a high-yield, lipid-rich microalgal species for sustainable energy generation, and these ideal growing circumstances offer a strong basis for its large-scale cultivation for a variety of biofuel applications.