Optimization and scaling up of extracellular polysaccharide production by submerged culture of Ganoderma lucidum on starch-containing medium using response surface methodology and laboratory bioreactors of various designs.

This article focuses on optimizing the production of exopolysaccharides (EPS) by the medicinal fungus Ganoderma lucidum using crude wheat starch as a renewable carbon source. Employing response surface methodology (RSM), the study identified an optimal medium composition—15 g⋅l⁻¹ wheat starch, 0.375 g⋅l⁻¹ ammonium chloride (NH4Cl), and 0.75 g⋅l⁻¹ calcium chloride (CaCl2) with a carbon-to-nitrogen (C/N) ratio of 40—that significantly increased EPS concentration and starch degradation during submerged fermentation. Scale-up experiments in stirred tank and column bioreactors demonstrated that cultivation conditions, particularly agitation intensity, influenced EPS yield and substrate consumption, with low-shear stress favoring starch degradation and higher agitation promoting EPS release. The findings highlight the potential for sustainable EPS production from inexpensive plant-based substrates without costly pretreatment, providing a basis for further research on stress factors and bioreactor design in fungal polysaccharide biosynthesis.