Identification, Structural Characterization of Exopolysaccharide from Sporidiobolus pararoseus PFY49

This study aimed to isolate a yeast strain capable of producing exopolysaccharide (EPS) from vineyard soil. The isolated EPS-producing yeast was identified through morphological observation and phylogenetic analysis based on 16S rDNA sequencing using the Neighbor-joining method. On this basis, EPS produced by PFY49 (PFY49-EPS) was separated and purified by Sephadex G-100 gel column, and its structure was characterized by Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy and atomic force microscopy. The results showed that the strain was Sporidiobolus pararoseus, named PFY49, with NCBI GenBank accession number MW784627.1. In addition, the weight average molecular weight of PFY49-EPS was 3.63×10⁵Da, mainly composed of polysaccharides such as mannose, glucuronic acid, glucose, galactose, and fucose. It was an O-glycosidic linked α-, β- pyranose without a triple helix structure and mainly existed in a disordered amorphous structure; Scanning electron microscopy and atomic force microscopy revealed that the surface of PFY49-EPS was relatively rough and uneven, covered with small holes and films, forming sharp or spike-like structures in aqueous solutions. This study reveals the structural characteristics of PFY49-EPS, providing a theoretical basis for the subsequent structural functional research of S. pararoseus EPS.