Enhancement of Growth, Lipid, and Carbohydrate Production of the Egyptian isolate Dunaliella salina SA20 Using Mozzarella Cheese Whey as a Growth Supplement

Abstract

THE growth of Dunaliella salina SA20 (Dunal) Teodoresco Egyptian isolate (from El-Bardawil Lake, Sinai, Egypt) in wastewater is a more cost-effective cultivation method. Wastewater, such as mozzarella cheese whey (MCW), is produced in massive quantities as a dairy industry byproduct, and growing D. salina in such waste could be used safely in biotechnological applications. Applying different organic MCW ratios to inorganic Loeblich nutrient medium (20, 50, 75% v/v MCW/Loeblich) as growth supplement allowed mixotrophic nutrition, while growth in completely inorganic medium (100% Loeblich medium) allowed for autotrophic nutrition. The optimum growth performance of D. salina cells was observed in 20% MCW and was indicated by measured values of chlorophyll a (10.51mg/L), dry weight (405mg/L), cell count (6.92 x 106 cell/ml), and optical density (1.12). Using 20% MCW, different pH values were applied to explore the pH effect on nutrient availability, and pH 7.5 was found to be optimal for growth. Additionally, a growth curve experiment comparing the mix-and autotrophic conditions presented higher values of the relative mean and maximum growth rates in mixotrophic conditions (0.19, 0.21 day−1, respectively) than in the autotrophic conditions (0.16, 0.18 day−1, respectively).