Influence of various concentrations of phosphorus on the antibacterial, antioxidant and bioactive components of green microalgae scenedesmus obliquus

Abstract

Background and Objective: The most nutritional factors that effect on the metabolism and cell growth is phosphorus. The concentration of phosphorus in the media can influence on the chemical contents and the biomass of microalgae. This study aimed to determine the effect of phosphorus concentrations on the carbohydrate, protein, lipids content and active components such as tannins, flavonoids, phenolic content, antioxidant, antibacterial activities and cholesterol reduction effect of Scenedesmus obliquus (S. obliquus). Materials and Methods: Scenedesmus obliquus was cultured in BG11 medium. The flasks were incubated at 28±2oC under continuous fluorescent light intensity of 180 μEm-2 sec-1 for 17 days at pH 7.5. Five different concentrations of phosphorous were added to the medium as K2HPO4 (0.001, 0.002, 0.005, 0.007 and 0.1g L-1) and effect of the five phosphorus concentrations on the carbohydrate, protein and lipids content of S. obliquus. The responses of the treatments were compared by analysis of variance (ANOVA) SPSS software version 16, one way ANOVA LSD≤0.5. Results: The results demonstrated that the best concentration of phosphorous was 0.007 g L-1 when the carbohydrate content was 18.13%, the highest protein content was 34.68% when the green microalgae were grown under phosphorous concentration was 0.007 g L-1. The best percentage of lipid content was 16% when the phosphorous concentration was 0.014 g L-1. The results demonstrated that the best concentration of phosphorous was 0.014 g L-1 media for production of the tennins concentration at 0.7 mg g-1 dry wt. and the flavonoid content at 200 μg g-1 algal dry wt., the best phosphorous concentrations had antioxidant activities of 35%. When the influence of phosphorus concentrations on the antibacterial activities of Scenedesmus obliquus was compared with Vancomycin, the highest inhibition was found with Staphylococcus sp. at 26 mm sand Vancomycin at 28 mm. Conclusion: Thus, various concentrations of phosphorus can affect in the chemicals composition of Scenedesmus obliquus and its activities.