The Effect Of Fermentation Conditions On Active Polysaccharides Accumulation Of Bjerkandera Fumosa

In recent years,because of the destruction of the environment and the excessive exploitation of the wild resources,the fruiting bodies of the medicinal fungi are becoming less and less,making the liquid fermentation process become the main way to prepare the mycelium and metabolites of medicinal fungi.However,at present,the study of the fermentation of medicinal fungi is mainly based on the optimization of the liquid fermentation conditions with the objective of the biomass of fungi or the maximum yield of intracellular and extracellular products.However,the effect of fermentation conditions on the species,composition and activity of fungal metabolites has rarely been reported.Under this background,the physicochemical properties,primary structure and biological activity of the Bjerkandera fumosa polysaccharides produced under different fermentation conditions were tested to explore the effects of the change of fermentation conditions on the yield,composition and activity of fungi polysaccharides,which will provide experimental basis for obtaining specific composition and specific activity of the polysaccharides from Bjerkandera fumosa,and also provide a theoretical and experimental basis for the related research on the metabolic regulation of medicinal fungi.The main contents and results are shown as follows:(1)Effects of fermentation conditions on growth status and polysaccharides accumulation of Bjerkandera fumosaThe experimental results showed that different carbon sources(glucose,corn flour,corn stalk,poplar sawdust),nitrogen sources(peptone,ammonium sulfate,soybean powder),rotating speed(120 rpm,150 rpm,180 rpm),addition accelerant(Tween-80,oleic acid)had certain effects on the morphology,growth state,and polysaccharides accumulation of B.fumosa.The highest fermentation conditions of mycelia were poplar sawdust 21.4 g/L,soybean powder 15.7 g/L,180 rpm 16.6 g/L,oleic acid 19.1 g/L.If the intracellular polysaccharide production was used as an index,the effect of carbon sources was corn flour > corn stalk > poplar sawdust >glucose;the effect of nitrogen sources was peptone > soybean powder > ammonium sulfate;the influence of rotating speed was 150 rpm > 180 rpm > 120 rpm;the influence of accelerant was oleic acid > control group > Tween-80.If the extracellular polysaccharide production was used as an index,the effect of carbon sources was corn stalk > poplar sawdust > corn flour > glucose;the effect of nitrogen sources was ammonium sulfate > soybean powder > peptone;the influence of rotating speed was180 rpm > 150 rpm > 120 rpm;the influence of accelerant was oleic acid > control >Tween-80.The above results indicated that mycelium biomass and polysaccharides production were certain affected by fermentation conditions.(2)Effects of fermentation conditions on physicochemical properties and primary structure of polysaccharides from Bjerkandera fumosaThe physicochemical properties and primary structure of deproteinized polysaccharides prepared under different fermentation conditions were tested.The contents of total sugar,protein,polyphenol,and uronic acid in different polysaccharides were determined by phenol-sulfuric acid method,Bradford method,Folin-phenol method and m-hydroxydiphenyl colorimetric method,respectively.The results showed that the composition of polysaccharides have changed in different fermentation conditions.Among the polysaccharides,the intracellular polysaccharide produced by oleic acid had the highest sugar content of 46.10%,and the intracellular polysaccharide produced by the poplar sawdust as the subsequent carbon source had the highest uronic acid content of 10.64%.In addition,the extracellular polysaccharide produced by the ammonium sulfate as the nitrogen source had the highest sugar content of 78.87%,and the extracellular polysaccharide produced by corn stalk as the subsequent carbon source had the highest uronic acid content of11.49%.The contents of total sugar and uronic acid in different fermentation conditions were quite different,and the difference between protein and polyphenol content was relatively small.The molecular weight and monosaccharide composition of polysaccharides were detected by HPGPC and HPLC.The results showed that the molecular weight and monosaccharide composition of polysaccharides from different fermentation conditions were inconsistent.The intracellular polysaccharides mainly consisted of glucose,mannose,and galactose,but the variety and content of monosaccharide were different.Such as,the xylose content of intracellular polysaccharides IPScs and IPSps produced by corn stalk and poplar sawdust as subsequent carbon sources was 6.7%and 6.6%,which were significantly higher than other intracellular polysaccharides.Most of the extracellular polysaccharides were mainly composed of glucose,and their content exceeded 60%,while the intracellular polysaccharide EPSg produced by glucose as carbon source was mainly composed of mannose with a content of 77.2%.(3)Effects of fermentation conditions on antioxidation activity and antitumor activity in vitro of polysaccharides from Bjerkandera fumosaThe intracellular and extracellular polysaccharides produced by different fermentation conditions had DPPH free radical,hydroxyl free radical scavenging activity,ferrous ion chelating activity and reducing power in dose-dependent manner,but the activity between different polysaccharides had certain differences.The assays of Hela cells proliferation inhibition in vitro was used to study the antitumor activity of different intracellular and extracellular polysaccharides.The results showed that most of polysaccharides could inhibit the proliferation of Hela cells,and the inhibitory effect of intracellular polysaccharides was higher than that of extracellular polysaccharides.But,the intracellular polysaccharide IPSoa produced by oleic acid could promote the proliferation of Hela cells.When the concentration of polysaccharides was 2.5 μg/μL,the inhibition rate of the intracellular polysaccharide IPScs produced by corn stalk as the subsequent carbon source was as high as 66.9%,and the inhibition rate of intracellular polysaccharide IPS120 produced by 120 rpm on Hela cells proliferation was 61.3%.The above results indicated that the antitumor activity in vitro was certain affected by fermentation conditions.