Schizophyllan Optimization and Production in Submerged Cultures of Different Schizophyllum commune Isolates Collected in Thailand

Twenty strains of Schizophyllum commune from the BIOTEC culture collection were selected for this study. S. commune is characterized by white to gray fan-shaped caps with lobed margins and distinctive split gills. Phylogenetic analysis of combined LSU rDNA and ITS rDNA sequences data using maximum parsimony placed the fungi in a strongly supported clade with S. commune. All strains were primarily screened for exopolysaccharide (EPS) and biomass production using potato dextrose broth (PDB) and peptone yeast glucose medium (PYGM) in 250 mL flasks shaken at 200 rpm for 7 days. The results revealed three strains with high EPS production, each exceeding 2.3 g/L, namely MMCR00487, MMCR00474 and MMCR00256. These strains were selected for media optimization using a Plackett–Burman design. Among them, MMCR00256 exhibited the highest EPS yield of 8.34 ± 1.47 g/L, followed by MMCR00487 and MMCR00474. Therefore, the strain MMCR00256 was further optimized by central composite design. The results revealed that the optimized medium for MMCR00256 increased the production of EPS to 10.39 ± 1.69 g/L, with a biomass yield of 26.28 ± 1.63 g/L (395 mg/g). The 5 L bioreactor optimization tested two inoculum types (mycelial and pellet) and two media (CCD and estimated) using strain MMCR00256. The mycelial inoculum grown in the estimated medium produced the highest EPS yield of 8.37 ± 0.26 g/L after 3 days, with 13.56 ± 2.94 g/L biomass. In conclusion, this study demonstrates that S. commune MMCR00256, when cultivated using the estimated medium and mycelial inoculum, can achieve enhanced exopolysaccharide production with improved efficiency, highlighting its significant potential for the development of efficient and scalable schizophyllan production processes at the industrial scale. Furthermore, this study provides essential insights into the cultivation and optimization of schizophyllan in S. commune.