Regulation of Schizophyllan in Schizophyllum commune
Summary
Schizophyllan (SPG) is an exopolysaccharide β-(1,3)-(1,6)-glucan produced by the fungus Schizophyllum commune. Despite its extensive applications in medicine and industry, its biological function remains unknown. This study aimed to clarify the role of SPG in S. commune. SPG production is known to be influenced by various factors, such as pH, medium composition, shear stress and temperature. Here, S. commune was exposed to various abiotic growth conditions. This study found the SPG production of S. commune was reduced when grown when grown in a highly buffered medium compared to low-buffered medium. Additionally, SPG production was increased when under heat stress. SPG production did not differ significantly between biofilm-like growth and shaken conditions. Possibly SPG acts as a physical barrier protecting S. commune against environmental stressors like acid and heat. Furthermore, this study found that deletion of fks1 (Schco3|2628724), the gene encoding the catalytic subunit of β-(1,3)-glucan synthase, only partially affected SPG production. Solid-state NMR analysis of the cell wall of the Δfks1 mutant showed that the reduction in SPG production was less pronounced compared to the reduction in β-(1,3)-(1,6)-glucan content in the cell wall. Possible reasons for this discrepancy include functional redundancy by the orthologue Fks2 or compensatory mechanisms within the fungus.