Optimization of Growth Conditions of Lentinus edodes Mycelium and polysaccharides on Walnut shell by-products Using Response Surface Analysis

Abstract

Lentinus edodes (L. edodes) is one of the most famous traditional Chinese medicines and high producer of various bioactive compounds such as polysaccharides. Modern pharmaceutical research shows that the Polysaccharides (LEPLS) of this mushroom is a kind of bioactive compound with clinical significance in medicine and several physiological effects. Up to now, fermentation system has been widely used successfully for the production of various biologically active compounds. Solid-sate fermentation techniques (fungal fermentation strategy) was carried out to produce LEPLs in L. edodes. Hence, the major objective of this study is the production of LEPLs through a developed process by using effective factors in order to achieve the optimal fermentation conditions for significant increase in the yields biomass and LEPLs. In this study, the optimal fermentation conditions of L. edodes polysaccharide using Walnut shell by-products as a substrate were investigated. RSM design of experiments method was used as the statistical method. Based on the optimum experimental conditions of SSF, the inoculum size, the incubation time, and the C/N ratio were optimized by RSM. The RSM model estimated that a maximal yield of biomass and polysaccharides (0.045 mg/g and 47.62 mg/g respectively) could be obtained when inoculum size, incubation time, C/N ratio was set at 20, 11.14, 25.66 respectively. As a result, the goodness of the quadratic model was determined by analysis of variance (ANOVA) and coefficient (R2). These values also verified by validation experiments. Finally, the optimal fermentation conditions resulted in a significant increase in the yields of biomass and LEPLs.