Growth Characteristics And Optimization Of Polysaccharide Production By Response Surface Methodology Of A Ganoderma Lucidum From Xinjiang

Ganodemra lucidum is a well-known medicinal mushroom particularly in China, Japan, and Korea. For centuries, the fruiting bodies of G. lucidum have been adopted by old folks to treat various ailments. However, the production of the fruiting bodies is time-consuming because the cultivation of basidiocarp requires at least three to five months.The production of G. lucidum mycelia used as a bioresource of polysaccharide is approximately six times faster than when fruiting bodies are utilised.The aim of this article was to isolate and identify a wild G. lucidum XJ-001 which was obtained from Altay, Xinjiang and study on the characteristics of growth and polysaccharide production and than optimization of mycelium biomass,Intracellular polysaccharide and extracellular polysaccharide of G. lucidum by Response Surface Methodology. Results of the research are as follows:1) Isolation and identification of XJ-001: The mycelium was isolated and purified from the fruiting body. Genomic DNA of strain XJ-001 was extracted from mycelium, and then used as template for the PCR amplification of ITS gene. ITS gene fragment was purified and sequenced. The sequence was analyzed with phylogenetic analysis method. Results show that: According to the morphological characteristics combined with rDNA-ITS analysis, the strain XJ-001 was identified as G. lucidum and GenBank accession number of the ITS gene was KT997431.2) Determination of optimum growth medium of XJ-001 strain: The strain XJ-001 was cultured on five different media. Optimal mother culture medium was selected by calculating mycelium growth rate. The effect of different carbon and nitrogen sources on mycelium biomass, intracellular and extracellular polysaccharide contents of the strain were studied by shake flask fermentation.Results show that: Thecorn soybean agar medium was chosen as excellent mother culture medium. The strain XJ-001 was cultured at 30℃ and 150 rpm for 5 days using glucose and yeast extract as the carbon and nitrogen source. Mycelium biomass, intracellular and extracellular polysaccharide contents were 8.15, 1.18 and 0.05mg/mL, respectively.3) Optimization of fermentation parameters for enhancing polysaccharide production by Response Surface Methodology: To optimize the culture medium and improve the contents of mycelium biomass, extracellular and extracellular polysaccharide from Xinjiang G. lucidum by Response Surface Methodology. The significant fermentation factors influencing mycelium biomass,intracellular and extracellular polysaccharide were screened by Plackett-Burman design. The optimum fermentation conditions were optimized with Box-Behnken experiment and the largest regional of mycelium biomass and extracellular polysaccharide contents was approach with the steepest ascent experiment. Results show that: The significant factors influencing mycelium biomass, extracellular polysaccharide and intracellular polysaccharide were glucose,yeast extract,liquid volume and pH, screened by Plackett-Burman design.The optimal fermentation medium were glucose 6.79%,yeast extract 0.65% and liquid volume 40.05%,the contents of mycelium biomass and extracellular polysaccharide were 24.93 mg/mL and 0.49mg/mL;The optimal fermentation medium were glucose 6.10%,yeast extract 0.57% and pH 5.68,the contents of intracellular polysaccharide were 2.43mg/mL,at the Box-Behnken experiment. under the optimal conditions,the contents of mycelium biomas, extracellular polysaccharide and intracellular polysaccharide were 23.91mg/mL,0.47mg/mL and 2.34mg/mL respectively,after being cultured in 25 L shake flask fermenter. The predicted value is close to the actual value,the model is well,suitable for the production of the fermentation tank.The production of biomass mycelium, extracellular polysaccharide and intracellular polysaccharide increased were 34.08%,11.6% and 50.65% respectively,with compared that before optimization. The result shows that the strain XJ-001 has the potential property to grow rapidly and produce high yield of polysaccharide, and this research will provide a reference for the development of Xinjiang wild G.lucidum resources.