Abstract

The medicinal mushroom Ganoderma lucidum is a source of polysaccharides used in disease treatment. The objective of this study was to investigate the relationships betweenG. lucidum mycelium morphology and the production of extracellular polysaccharides (EPS) in submerged fermentation. Mycelium pellets were classified according to diameter as either S, M or L pellets. M pellets were the main source of EPS. Changes in mycelium morphology and EPS production were obtained when cells were grown in different culture media; medium that contained a high concentration of glucose and low peptone enhanced the formation of M pellets. The proportion of M pellets in the culture was influenced greatly by KH₂PO₄ concentration and increase was accompanied by enhanced EPS production. Dry cell weight was affected mostly by the percentage of total M and L pellets present, while S pellet numbers had little effect. The production of EPS and the accumulation of mycelia were influenced mainly by G. lucidum pellet morphology. This study suggests that in large scale fermentation, high yields of EPS would be obtained by the control of mushroom morphology.

Key words: Medicinal mushroom, Ganoderma lucidum, morphology, extracellular polysaccharides, submerged fermentation.