Ganodermalucidum is one of the most famous medicinal mushroom that is used as a health food and medicine in the Far-East for more than 4000 years. Recent studies indicate that G. lucidum mycelium contains major bioactive components such as polysaccharides and ganoderic acid. These compounds are used normally for therapeutic application especially for cancer prevention.The aim of this research isoptimization of polysaccharide compounds production byGanodermalucidumin vitro as a source of pharmaceutical product for human cancer prevention. The experiments were divided to two parts for optimizing the therapeutic compounds production by G. lucidum. In the first part, two strategies (seed culture on agar or preparation in submerged fermentation) for preparation of mycelialinocula for submerged fermentation was investigated. In the second part, the effect of some parameters such as carbon source (glucose, lactose and maltose), carbon concentration and pH on mycelia dry weight, extracellular polysaccharides (EPS) and intercellular polysaccharides (IPS) production in liquid culture was evaluated. Response surface methodology was used to optimize each parameter. The data were analyzed using Minitab 16 software The results showed that an initial pH value had a significant effect on cell growth and product biosynthesis. According to the results, the highest mycelia biomass (7.57g DW/l), EPS (326.4 mg/l) and IPS (389.55 mg/l) was produced in media that containedmaltose as a carbon source. Lowering the initial pH gradually led to a higher production of EPS and the higher specific production of IPS, as well as increasing the initial pH gradually led to a higher biomass production and IPS. The highest production of total polysaccharide and biomass was achieved with a pH value of 4.89 and maltosesource with 49 g.l-1. The results of the research confirmed that in vitro culture of Ganodermalucidum is a potent system for production of important medicinal polysaccharide which are responsible for human cancer prevention and their production could be maximized by changing the media parameters such as carbon source and media pH.

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