Evaluation of total exopolisaccharide produced by Prasinococcus sp. and Porphyridium cruentum under different cultivation conditions

Prasinococcus sp. (green microalgae) and Porphyridium cruentum (red microalgae) are good candidates for the production of valuable biochemicals such as polysaccharides. The aim of this study was to investigate sugar amount of Prasinococcus sp. in comparison with Porphyridium cruentum as a control strain under two different light intensities (10 and 50 µE m-2 s-1 with the light-dark cycle of 16h:8h) in F/2 medium with or without sodium bicarbonate and sodium monohydrate glyoxylate enzyme, respectively. Experiments were carried out in 1000 ml Erlenmeyer flasks containing 900 ml of F/2 medium at the air flow rate of 1 vvm under the temperature of 22±2 °C for 14 days. Irradiance was measured in the center of the flask with a quantum meter (Lambda L1-185). During the cultivation period chlorophyll-a, optical density and total sugar amounts were measured. After 14 days of cultivation period the highest total sugar concentration (275.5 mg/L) and the maximum chlorophyll-a amount (5.99 mg/L )were obtained under the light intensities of 50 µE m-2 s-1in F/2 medium without NaHCO3 for Prasinococus sp. and the highest total sugar concentration (246.53mg/L) obtained from P. cruentum and the maximum chlorophyll-a amount (5,37) were obtained for Prasinococcus sp. under the light intensities of 50 µE m-2 s -1 with adding sodium glyoxylate monohydrate enzymeto F/2 medium. It was reported that the existence of NaHCO3 has no effect on sugar production of both microalgae, whereas adding 0.25 mmol/L glyoxylate monohydrate enzyme caused an increase in sugar production of Porphyridium cruentum under the light intensity of 50 µE m-2 s-1. Higher light intensity triggered the sugar production of Prasinococcus sp. but adding both of chemical components to the medium didn't have any remarkable effect on sugar production of this microalgae.