Optimisation of biomass, exopolysaccharide and intracellular polysaccharide production from the mycelium of an identified <em>Ganoderma lucidum</em> strain QRS 5120 using response surface methodology

Abstract

Wild-cultivated medicinal mushroom <i>Ganoderma lucidum</i> was morphologically identified and sequenced using phylogenetic software. In submerged-liquid fermentation (SLF), biomass, exopolysaccharide (EPS) and intracellular polysaccharide (IPS) production of the identified <i>G.</i> <i>lucidum</i> was optimised based on initial pH, starting glucose concentration and agitation rate parameters using response surface methodology (RSM). Molecularly, the <i>G. lucidum</i> strain QRS 5120 generated 637 base pairs, which was commensurate with related <i>Ganoderma</i> species. In RSM, by applying central composite design (CCD), a polynomial model was fitted to the experimental data and was found to be significant in all parameters investigated. The strongest effect (<i>p</i> < 0.0001) was observed for initial pH for biomass, EPS and IPS production, while agitation showed a significant value (<i>p</i> < 0.005) for biomass. By applying the optimized conditions, the model was validated and generated 5.12 g/L of biomass (initial pH 4.01, 32.09 g/L of glucose and 102 rpm), 2.49 g/L EPS (initial pH 4, 24.25 g/L of glucose and 110 rpm) and 1.52 g/L of IPS (and initial pH 4, 40.43 g/L of glucose, 103 rpm) in 500 mL shake flask fermentation. The optimized parameters can be upscaled for efficient biomass, EPS and IPS production using <i>G. lucidum</i>.