Nannochloropsis sp. and Tetraselmis sp. protein targeted culture because no artificial continuous lighting and salinity adjustment were required. Slight fluctuation in salinities (20e40 ppt) that usually occur under natural condition as a result of evaporationwas not significant. In fact, Nannochloropsis sp. showed a significantly higher protein content when cultured under natural condition as compared to control condition. The protein contents of Nannochloropsis sp. (51e60.7%) in natural condition were much higher than the reported value which was approximately 40% in the same species (Chiu et al., 2009). This significantly high protein content of natural condition could be caused by the higher outdoor temperature, which range from 27 to 39 C and high light intensity (1260e39 878 lux) as compared to control condition. The high protein content of microalgae culture in natural condition could also due to the lightedark period of the natural condition enables the production of the protein synthesis during dark period (Allakhverdiev et al., 2005).