The Effects of Paraxanthine on Dunaliella Salina, a Saline Waters Alga from Physiologycal and Biochemical view Points

Esmaelzadeh, Sayfallah (2020) The Effects of Paraxanthine on Dunaliella Salina, a Saline Waters Alga from Physiologycal and Biochemical view Points. Masters thesis, University of Mohaghegh Ardabili.

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Abstract

Research Aim: Evaluation of the effect of paraxanthin as pollutant on the aquatic ecosystems of the algae Dunaliella salina, paraxanthin can enter saline waters through human metabolism or caffeine microbial biodegradation by microorganisms in the environment and as an allelochemical and stressful compound causes physiological and biochemical responses in algae Dunaliella salina. Research method: Firstly Johnson culture medium was prepared for algae propagation, then transferred from the existing stock to culture medium until the algae was grown in constant culture medium, then three concentrations of 0.01, 0.1 and 1 μg of paraxanthine in three groups. In addition, a control group was treated individually for two weeks, and after collecting the algae and preparing algae extract, the assays were performed three times in each treatment and control groups. Findings:. The effect of paraxanthin on chlorophyll fluorescence of D.salina algae increased Fo at high concentration but at low concentration did not change significantly. Fm decreased with decrease in paraoxanthine concentration, but there was no significant change in the other treatments. In all three treatments, the decrease in Fv/Fm was significant, chlorophyll a was unchanged but chlorophyll b decreased only in high concentrations. Carotenoid, total protein and free amino acids content decreased but proline content increased in different treatments compared to the control group. H2O2 and soluble sugar did not change significantly at low concentration but increased with increasing paraoxanthine concentration. APX and PPO enzymes activity increased at high concentration, but catalase and protease decreased significantly compared to the control group. Conclusion: The present study showed that paraxanthin introduced into the algae environment caused some biochemical and physiological responses in algae, which altered significantly in the amount of enzymatic and non-enzymatic antioxidants and decreased the amount of carotenoids. So, the enter of paraxanthin as an allelochemical into the aquatic habitat should be considered.

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