| In this experiment,Shiitake 168,Shiitake 868 and Wuxiang No.1 were used as materials to study the effects of different carbon,nitrogen sources and carbon-nitrogen ratio on mycelium growth,extracellular enzyme activity,intracellular and extracellular polysaccharide content and lignin degradation ability of the strains,in order to provide theoretical and technical support for the types and utilization efficiency of carbon and nitrogen sources to improve the yield and quality of Lentinus edodes.The research results are as follows.1.Using glucose,sucrose,maltose,fructose and soluble starch as five carbon sources and yeast extract,glutamine,proline,ammonium chloride and potassium nitrate as five nitrogen sources,the growth potential of Lentinus edodes mycelium was determined by single factor culture.The results showed that the growth potential of Lentinus edodes 168,Lentinus edodes 868 and Wuxiang No.1 was the best when soluble starch and yeast extract were used as carbon and nitrogen sources.Taking soluble starch as carbon source and yeast extract as nitrogen source,eight concentration gradient C/N ratios(5:1,10:1,201,30:1,40:1,50:1,60:1,70:1respectively)were set.When the C/N ratio of Lentinus edodes 168 was 30:1,the mycelium of Lentinus edodes 168 increased.When the C/N ratio of Lentinus edodes868 and Wuxiang No.1 is 50:1,the mycelium growth rate and growth potential are the best.2.Determination of extracellular enzyme activity of Lentinus edodes mycelium.The results showed that five kinds of carbon sources and five kinds of nitrogen sources had significant differences on the extracellular enzyme activities of the three strains.The hemicellulase activities of the three strains were significantly higher than those of the other two enzymes under different carbon sources.Among them,the difference under nitrogen source treatment is obvious.The extracellular enzyme activity of Lentinus edodes 168 and Wuxiang No.1 is hemicellulase activity > amylase activity > carboxymethyl cellulose activity,while that of Lentinus edodes 868 is carboxymethyl cellulose activity >hemicellulase activity > amylase activity.In the C/N ratio test,the differences among the three kinds of extracellular enzyme activities of the three strains reached a significant level,and with the increase of C/N ratio,the extracellular enzyme activities of the strains gradually increased.When the C/N ratio exceeds 50:1,the extracellular enzyme activity of the strain gradually weakens.3.Determination of intracellular and extracellular polysaccharide content in Lentinus edodes mycelium.The results showed that there was no significant difference in extracellular polysaccharide content among the three strains with five carbon sources.Soluble starch was the carbon source,and the three strains were significantly higher than the other four carbon sources.Using yeast extract as nitrogen source,the contents of intracellular and extracellular polysaccharides of the three strains were significantly higher than those of the other four nitrogen sources.Among them,Lentinus edodes 168 was significantly superior to the other two strains in intracellular and extracellular polysaccharide accumulation under carbon and nitrogen sources.4.Determination of degradation of lignin in bag culture substrate by Lentinus edodes.The results showed that the degradation ability of lignin of the three strains under maltose treatment was stronger than that of other carbon sources,and the degradation ability was maltose > glucose > sucrose > soluble starch > fructose.The degradation ability of lignin of the three strains under glutamine treatment was stronger than that of other nitrogen sources,and the degradation ability was glutamine > proline > ammonium chloride > yeast extract > potassium nitrate.Among them,Wuxiang No.1 is significantly superior to the other two strains in lignin degradation under carbon source conditions,and Lentinus edodes 868 is superior to the other two strains in lignin degradation under nitrogen source conditions.To sum up,the types of carbon and nitrogen sources required by the three Lentinus edodes strains and their utilization efficiency are correlated,that is,the best carbon and nitrogen sources are soluble starch and yeast extract respectively in the mycelium stage,and the best ratio of carbon to nitrogen is 30:1～60:1.At the same time,the types of carbon and nitrogen sources affect the accumulation of polysaccharide content inside and outside the cell,while the best carbon and nitrogen sources are maltose and glutamine respectively in the degradation of lignin from the mycelium to the fruiting body stage of Lentinus edodes. |
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