Efficient biomass-exopolysaccharide production from an identified wild-Serbian Ganoderma lucidum strain BGF4A1 mycelium in a controlled submerged fermentation

A wild-Serbian medicinal mushroom Ganoderma lucidum strain BGF4A1 (GLSB) was isolated from Mount Avala, Serbia and morphologically identified based on its brown-liquorish cap and woody stipe. Molecularly, GLSB (642.8 bp) was sequenced and found to be 99% similar to the Serbian-originated G. lucidum strain BEOFB 434 and G. lucidum strain BEOFB 431. The isolate belongs to the G. lucidum species as the sequence dissimilarities (K_nuc) value between both sequences of the same fungal species was 0.001. In submerged-liquid fermentation, biomass and exopolysaccharide (EPS) production of GLSB was optimised using response surface methodology. The interactions between three variables: initial pH (4–6), temperature (20°C–30 °C), and glucose concentration (10 g/L–50 g/L) were analysed using a central composite design. An analysis of variance revealed that the model was significant for all parameters investigated (p < 0.05). Temperature and glucose concentration were found to significantly influence mycelial biomass production, whereas for EPS production only glucose concentration had a significant effect. The model for biomass and EPS was validated by implementing the optimised conditions (pH 5.26, 50 g/L glucose, and 30 °C) and was found to generate the highest biomass (3.12 g/L) and EPS (1.96 g/L). An efficient EPS-biomass production blueprint was thus established using optimised parameters for large-scale cultivation of Serbian G. lucidum strains.