Introduction
Microcystis aeruginosa is the most common algae in water blooms, and can
release toxic and harmful algal toxins into the environment[1-4]. There are two kinds of glutathione in algal
cells, one is reduced glutathione (GSH), the other is oxidized
glutathione (GSSG).However, glutathione in algal cells exists in the
form of reduced glutathione (GSH) in most cases, and GSH has high
reducibility [5-8]. Under certain conditions,
oxidized glutathione (GSSG) and reduced glutathione (GSH) can be
transformed into each other [9-11]. When stressed,
there will be reactive oxygen species (ROS) in microalgae cells, which
can cause GSH to be oxidized to GSSG [12-14].As
the most abundant free mercaptan in microalgae cells, GSH maintains the
best intracellular oxidation environment to play the normal function of
cell proteins [15]. In general, the level of GSH
in microalgae cells will affect the redox status of the cells[16].
GSH in microalgae cells can also be converted into phytochelating
peptides (PC) and ascorbic acid (ASA) with the participation of various
enzymes [17-20]. Under the action of
phytochelating peptidases (PCs), GSH can be synthesized into PC to form
low-molecular-weight complexes, which are then further converted into
high-molecular-weight multimeric complexes and preserved in Microcystis
aeruginosa cells [21]. GSH exerts its important
antioxidant stress role through the ascorbic acid-glutathione (ASA-GSH)
cycle [22-24].
Therefore, under the influence of environmental changes, glutathione and
enzymes in algal cells undergo some synergistic changes and interact
with each other [25, 26], but with the progress of
metabolism, it is difficult to accurately detect and analyze the changes
of each living substance by existing biochemical methods. In this study,
we investigated the changes of GSH in different growth stages of
Microcystis aeruginosa and its correlation with the synergistic changes
of phycocyanin and enzymes, and analyzed the changes of carboxylated
biomolecules in the growth and metabolism of Microcystis aeruginosa by
covalent coupling method, mainly including the changes of GSH,
phycocyanin and SOD enzymes. The distribution of GSH content in
different stages was clear, no other interference in the system, good
correlation, changes in the number of peaks and peak area of GSH content
in the three-dimensional fluorescence spectral region, and the maximum
GSH content in the algal cells at d 50. There are physiological
activities between GSH synthesis, GSH/GSSG interconversion, synthesis of
phytochelating peptide (PC), ASA-GSH cycle and metabolism in algae. The
interaction between GSH synthesis, GSH/GSSG interconversion,
phytochelating peptide (PC) synthesis, ASA-GSH cycling and metabolism
was found to maintain the antioxidant properties of microalgae.