Effects of different pH on the microalgae protein and carbohydrate contents in this study were found to be in accordance with Khalil et al. (2010). It was reported that the protein and carbohydrate of D. bardawil attained their maximum values at pH 7.5.Shifting the pH value towards the acidic or alkaline side significantly decreased the content of protein when cultured under control condition. This study showed that the highest protein content was evident in Nannochloropsis sp. cultured at 30 ppt under natural condition as compared to Tetraselmis sp. and all other treatments.The optimal pH value for high protein content production was pH 7.5e8.5 under control condition.