Isolation and Enzymatic Characterization of Fungus Degrading Salvia miltiorrhiza Residue Lignin
[Objective]Selecting fungus that degrades Salvia miltiorrhiza residue(SMR)lignin and exploring its enzymatic characteristics is for having a strain to degrade SMR lignin for improving the enzymatic hydrolysis efficiency of cellulase.[Method]The strains naturally growing on the surface of SMR were selected as the screening source.Basic lignin medium and guaiacol medium were used for preliminary screening,and the medium added with SMR was used for re-screening to select the laccase-producing strains.The strains were identified by ITS sequence analysis.The enzymatic characteristics of laccase from isolated strains were studied.The content of lignocellulose was determined by NREL method,and the enzymolysis effect was investigated by commercial cellulase.[Result]A laccase-producing and SMR-tolerant fungus MY-5 was selected and identified as Trichoderma erinaceum by ITS sequence.The enzymatic properties of laccase were investigated.The optimal reaction temperature was 50℃,the enzyme activity was maintained at 85.3%after 24 h at 60℃,and 80.7%after 25 d of low temperature storage at 4℃.The optimal pH was 5,and the activity remained above 90%at pH 4-8 for 24 h.Adding Cu2+and Mg2+and vanillin increased the activity of laccase,and 5 mmol/L Cu2+increased to 1.68 times.Adding 4%SMR and holding it for 24 h,90.6%laccase activity still was maintained.After 20 d of liquid fermentation,SMR lignin degradation rate reached 36.3%,and the glucose yield and maximum yield increased by 62.6%and 81.0%,respectively.[Conclusion]A laccase-producing and SMR-tolerant T.erinaceum MY-5 had been isolated,which had good thermal stability,low temperature storage stability,pH stability and resistance to SMR,which may effectively degrade SMR lignin and improve the efficiency of cellulolytic enzyme hydrolysis,providing a basis for the bio-utilization of Chinese medicinal residue.
Salvia miltiorrhiza residueTrichoderma erinaceumlaccaseenzymatic characterizationdelignification
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