Figure 3 Changes of GSH in algae cells at different growth stages (a) and (b). Two-dimensional correlation fluorescence spectra (c) .Two-dimensional asynchronous correlation fluorescence spectra and (d)
As Figure 4,the three-dimensional fluorescence spectrum of GSH shows that during the growth period of microalgae, GSH is mostly in the initial synthesis stage, so only one regional peak (region A) appears in the contour plot and the peak area is small, and the peak height of GSH in the three-dimensional fluorescence stereogram is low; On day 21, Microcystis aeruginosa starts to enter the logarithmic growth period, and the GSH in the algal cell starts to synthesize and transport, and only one regional peak (region A) appears in the contour plot. On day 50, the intracellular GSH content reached its maximum, and the peak area was the largest at this time, with three regional peaks, the outermost region A, the middle region B and the innermost region C. The three-dimensional fluorescence map showed the highest peak height of GSH at this time. GSH is being synthesized, GSH/GSSG interconversion, ASA-GSH cycle and synthesis of phytochelating peptide (PC) to play its antioxidant role; Figure d enters the decay phase, the intracellular GSH begins to metabolize and degrade, only two regional peaks (region A and region C) remain and begin to decrease, and the peak height of GSH shown in the three-dimensional fluorescence stereogram begins to decrease Until the algal cells were completely dead, GSH was degraded to L-γ-glutamylcysteine (L-γ-Glu-L-Cys, γ-EC), γ-glutamyl cycle potential substrate, γ-glycine cysteine and other free amino acids by the catalytic action of carboxypeptidase (CPase) and γ-glutamyl transpeptidase (γ-GTase). The distribution of GSH content at different stages was clear, and there were no other interferences in the system.