The Impact of γ-irradiation on Photosynthetic Activity (14CO2-assimilation), Photosynthetic Pigments, Enzymes, and Biomass Productivity of Chlorella vulgaris

     Recently, γ-irradiation has become more popular as a way to increase total yield and phytochemical components in many plants, including microalgae. A significant increase in the use of γ-irradiation to stimulate biological processes in microalgae have been witnessed. Among functional ingredients identified from marine algae, the three basic classes of natural pigments are chlorophylls, carotenoids, and phycobiliproteins. The γ-irradiated Chlorella vulgaris treatment at a dose of 200Gy significantly increased the photosynthetic pigments (chlorophyll a, b, total chlorophyll, carotenoids, C-phycocyanin, allophycocyanin, phycoerythrin, and total phycobiliproteins) and photosynthetic enzyme activities (ribulose-1,5-bisphosphate-carboxylase/oxygenase, RUBISCO and phosphoenol-pyruvate carboxylase, PEPCASE), as compared to the control. The results showed a significant increase in photosynthetic activity (¹⁴CO₂-assimilation), total carbohydrate contents, and total biomass productivity, which in turn increased the total yield of γ-irradiated C. vulgaris compared to the control. Meanwhile,forthesize of chloroplasts, no significant changes were detected in either the γ-irradiated C. vulgaris (200Gy) or control sample. The data revealed that the potential application of γ-radiation as a stimulatory agent to increase the total biomass productivity and nutritive value of C. vulgaris, as they increased chlorophylls, carotenoids, and phycobiliproteins contents, may have the potential to be used as a food supplement for treatment of countless diseases.