Dunaliella species are unicellular, photosynthetic and motile biflagellate microalgae, morphologically distinguished by the absence of a rigid cell wall. Dunaliella salina, one of the best known Dunaliella species, is an algal species rich in β-carotene, glycerol and fatty acids, especially being salty environments (Ben-Amotz, 2004; Oren, 2006). In this study, the growth kinetics of four different Dunaliella salina strains were compared in a mixotrophic growth medium combining phototrophic and heterotrophic growth. Mixotrophic cultivation is useful to overcome the problems imposed by phototrophic or heterotrophic growth by providing the advantage of obtaining a large biomass and high biochemical contents (Gim et al.,2014). The growth of three different commercial species was compared with that of the species isolated from Salt Lake. Five different organic carbon sources were used: glucose, glycerol, acetic acid, sodium bicarbonate and sodium acetate. Sodium nitrate, urea, ammonium nitrate and ammonium sulfate were used as nitrogen sources. As a result of the study, the strain isolated from Salt Lake reached higher cell numbers in mixotrophic conditions compared to autotrophic nutrient media. However, no growth was observed in commercial strains under mixotrophic conditions containing organic carbon. Growth was observed in all strains only when sodium nitrate was used as nitrogen source. It was concluded that the strain isolated from Salt Lake was more suitable for mixotrophic production.

KEYWORDS

Dunaliella salina, microalgae, mixotrophic culture