Selection Of Strains Of Higher Production Of Grifola Frondosa Polysacchrides And Its Characteristic Research Of Liquid Fermentation

A new strain of high-yielding polysaccharide which was named WUV-4was bredaccording to microwave-UV mutation method using the mycelium of Grifolafrondosa Gf-3, then the liquid fermentation and metabolites product (polysaccaride)of the strain WUV-4were studied.The original strain Gf-3mycelium were treatmented by different time UV-radiation after70s microwave-irradiation, and the nine different time were1min、3min、5min、10min、15min、20min、30min、40min、50min. The mutated strainschanging significantly were selected.The tested strains were identified by means of antagonistic test and peroxidaseisoenzymes test, and six mutant were obtained which were named WUV-1, WUV-2,WUV-3, WUV-4, WUV-5, WUV-6.The comparative test on the capability of producing polysaccharides of the testedstrains in liquid fermentation indicated that mutant strain WUV-4had the highestpolysaccharides production while culturing in the flask culture and which increased48.8%comparing to the original strain. What′s more, the genetic stability test alsodemonstrated that the strain WUV-4did not reverse mutation, so it was selected forthe subsequent.The optimization results of the liquid fermentation medium of strain WUV-4showed that glucose and peptone were the best carbon and nitrogen source. And theoptimal concentration of glucose and peptone respectively were33.03g/L and2.65g/L by way of response surface methodology.Effects of plant oil addition on the production of mycelial biomass andintracellular polysaccharide (IPS) and extracellular polysaccharide (EPS) weredifferent. It was found that the production of mycelial biomass was greatly enhancedwith plant oils, but the plant oils had no significant effect on the IPS production.Furthermore, rapeseed oil and cottonseed oil could improve the EPS production, yetthe soy oil failed to enhanced the EPS production and in most instances it evenslightly inhibited the EPS production. Meanwhile, the result showed that the plant oilconcentration of1.5%(V/V) was suited for liquid fermentation. In addition, from themorphology observation, the morphology of mycelia in culture with oil additionshowed an obvious time extension before the pellet lysis. Expansion cultivation experiment of strain WUV-4was carried out in10Lfermentor, the results showed that the three parameters such as pH, dissolved oxygenand reducing sugar concentration gradually decreased in the whole process, however,the production of mycelial biomass and EPS gradually increased, and pH as wellasmycelial biomass could be as reference of the end of fermentation.After Sephadex G-200column chromatography, one fraction named EPS-1wascollected of EPS, and two fractions which named IPS-1and IPS-2were collected ofIPS. The order of the molecular weight of three components was IPS-2>EPS-1> IPS-1according to the elution time. Furthermore, it was noted that three components are thepolysaccharides via IR.