The mechanistic study of using microparticle Al2O3 to promote the production of exopolysaccharides in submerged fermentation of Antrodia cinnamomea

In this study, a notable increase of 136.9% in the production of exopolysaccharides (EPS) was observed during the submerged fermentation of Antrodia cinnamomea when microparticle (4 g/L of Al2O3) was applied. By evaluating the activities of key enzymes involved in EPS synthesis in A. cinnamomea, it was found that the addition of Al2O3 enhanced the activities of phosphoglycerate mutase (PGM), UDP-glucose pyrophosphorylase (UGP), and GDP-mannose pyrophosphorylase (GMPPB). To further elucidate the mechanism through which Al2O3 enhances the production of EPS in A. cinnamomea, a transcriptomic analysis was conducted to compare the gene expression levels. The results showed that there was a significant up-regulation of genes associated with the synthesis and assembly of polysaccharide repeating units, as well as genes responsible for the regulation of ABC transporter complex enzymes. To verify the above hypothesis, the ABC transporter inhibitor MK-571 sodium salt was added to the fermentation broth of A. cinnamomea. The study demonstrated that when the ABC transporter was inhibited, the yield of EPS was significantly reduced, which further confirmed that the addition of Al2O3 could improve the activity of ABC transporter and promote the production of EPS in submerged fermentation of A. cinnamomea.