Abstract: In this paper, the sugar-producing strains, synthesis pathways, influencing factors and applications of cyanobacterial extracellular polysaccharides were introduced. The four synthesis mechanisms of Wzx/Wzy-dependent pathway, ABC transporter-dependent pathway, synthase-dependent pathway and sucrase synthesis pathway were analyzed in detail, as well as the application prospects of cyanobacterial extracellular polysaccharides in the fields of medicine, food and environmental remediation. It pointed out that the current research on cyanobacterial exopolysaccharides has shortcomings in the analysis of the relationship between structure and function, the molecular regulation mechanism of the synthetic pathways, and large-scale production models. It proposed that the regulatory network of cyanobacterial exopolysaccharide synthesis should be further elucidated through multi-omics technology in the future, and efficient extraction and purification processes should be developed, and an optimization model of biomass and cyanobacterial exopolysaccharide production should be established to promote its in-depth development and industrial application in the fields of biomedicine, environmental remediation, and sustainable agriculture.

Key words: cyanobacteria, extracellular polysaccharide, synthetic pathway, influencing factor, application prospect