Studies On The Liquid Fermentation Technology And Bioactivities Of Collybia Radicata

Collybia radicata is a rare edible and medicinal mushroom, tasty flavor, and rich inpolysaccharides, fatty acids, protein, amino acids, minerals and other nutritionalcomponents. Fermentation metabolites of Collybia radicata which has good antimicrobialactivities is very rich, and the polysaccharides of Collybia radicata have antioxidantactivity, enhance immune activity and have inhibitory effects of tumor growth. Recently,the study of Collybia radicata mainly focus on cultivation and domestication, but thestudy of liquid fermentation, antimicrobial activities of the fermentation broth, isolationand purification of Collybia radicata polysaccharides and antioxidative activities of thepolysaccharides have not been reported.The main content of this thesis includes: study on liquid culture technology ofCollybia radicata, preliminary study on antimicrobial activities of the fermentation broth,study on isolation and purification of polysaccharides and its antioxidative activitiesresearch.1. Formula screening results showed: in shaking flask, the best carbon source,nitrogen source, inorganic salts and growth factor were screened by single-factorexperiment in fermentation media. Then the optimum levels were selected by orthogonalexperiment. The fermentation media obtained to fit for Collybia radicata was: sucrose30g/L, soybean meal 9g/L, inorganic salts composition KH₂PO₄ 5g/L and MgSO₄·7H₂O2.5g/L, growth factor vitamin B₁ 0.2g/L.The optimum conditions obtained by single-factor experiment were: cultivationtemperature 26℃, loading volume 100mL of 250mL flask, rotation speed 180r/min,inoculation volume 10ï¼…(v/v) and initial pH5.5.Verification tests indicated that the above conditions were the best condition forCollybia radicata liquid fermentation, mycelium dry weight reached 1.514g/100mL andextracelluar polysaccharide were up to 0.291 g/100mL.2. The experiments of antimicrobial activities of Collybia radicata fermentationbroth showed that it had some inhibitory effects to common pathogens. The broth had thestrongest inhibitory activity to Erwinia carotovora in the 7 species of tested bacteria, withthe inhibition zone diameter 4.3mm, and Pyricularia grise was severely inhibited in the 6species of tested fugues, the inhibition rate is more than 99ï¼….Stability tests showed that the fermentation time between 11～13d exhibited thestrongest inhibitory activity, and the inhibitory activity is lower with the increasing temperature, whereas the inhibitory activity were up to 52.804ï¼…when the broth weretreated at 100℃. Otherwise, the fermentation broth exhibited high activity under pH5.5～7.0, and it is likely sensitive to UV light.3. Antioxidant tests of different sources of Collybia radicata polysaccharides (drymycelium polysaccharide, fresh mycelium polysaccharide, extracelluar polysaccharide,cap polysaccharide, handle polysaccharide) and the fermentation broth showed that theyall had certain antioxidative activities.Various sources of polysaccharides had a strong DPPH- free radical scavengingeffect, which dry mycelium polysaccharide exhibited the strongest scavenging activitywith EC₅₀(DPPH.) value 0.394mg/mL, and the scavenging activities increased with theincreasing concentration. In contrast to the positive control vitamin C and vitamin E,scavenging effects of the different sources of polysaccharides were better than vitamin E,But worse than vitamin C.Reducing power test found that the value increased with the increase ofconcentration of polysaccharides. Extracelluar polysaccharide and dry myceliumpolysaccharide showed the greatest"reducing powers, with ECs0 (reducing power),respectively 0.478mg/mL and 1.068mg/mL. But the reducing powers of various sourcesof polysaccharides were worse than the positive control vitamin C.Various sources of polysaccharides had a strong ferrous ion chelating capacity, andthe chelating capacity increased with the increasing concentration. Fresh myceliumpolysaccharide showed the greatest ferrous ion chelating capacity, with EC₅₀ (reducingpower) 0.126mg/mL. But the ferrous ion chelating capacities of various sources ofpolysaccharides were worse than the positive control EDTA.