Compatibility of ascorbate-glutathione cycle enzymes in cyanobacteria against low and high UV-B exposures, simultaneously exposed to low and high doses of chlorpyrifos

This study deals with the comparative responses of the two cyanobacteria viz. Nostoc muscorum and Phormidium foveolarum against single and combined doses of low (UV-BL, 0.1 μmol m−2 s−1) and high (UV-BH, 1.0 μmol m−2 s−1) fluence rates of ultraviolet-B radiation with low (CPL, 1 μg ml−1) and high (CPH, 2 μg ml−1) doses of the insecticide chlorpyrifos by measuring changes in growth, ascorbate-glutathione cycle enzymes and related metabolites. CPL and UV-BL both caused lesser increase in ROS but significantly stimulated AsA-GSH cycle enzymes. On the other hand, CPH and UV-BH posed inhibitory effects by enhancing ROS and inhibiting AsA-GSH cycle enzymes. Inhibitions in CPH or UV-BH treated samples were significantly prevented when they were supplemented with UV-BL and CPL (after 72 h), respectively by lowering down ROS and enhancing AsA-GSH enzymes and related metabolites which manifested in terms of improved biomass accumulation.

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► CPL and UV-BL were growth stimulatory, accompanied with lesser increase in ROS.
► This was accompanied by an increase in all components of AsA-GSH cycle enzymes.
► CPH and UV-BH were growth inhibitory, appeared in more increase in ROS.
► This was accompanied with decrease in all components of AsA-GSH cycle enzymes.
► UV-BL/CPL with CPH/UV-BH significantly alleviated inhibitory effects of CPH/UV-BH.