Screening and optimization of solid-state fermentation conditions of high cellulase-producing strain and its enzymatic property
In this study,the high cellulase-producing strain was screened from 12 fungi preserved in the laboratory,and identified by morphological observation and molecular biology techniques.Using cellulase activity as the evaluation index,the solid-state fermentation conditions of the screened strain were optimized by single factor tests and orthogonal tests,and the cellulase activity was compared with that of the reported high cellulase-pro-ducing strains.Finally,the enzymatic properties of the crude cellulase were preliminarily investigated.The results showed that a high cellulase-pro-ducing strain of Trichoderma asperellum BW-6 was screened and identified,with the filter paperase(FPase)and carboxymethyl cellulase(CMCase)activities reached 1.99 U/g and 7.02 U/g,respectively,and the optimal solid-state fermentation conditions were as follows:wheat bran+bagasse+rice straw(2.0 g+1.5 g+1.5 g)as solid-state fermentation substrate,0.5％peptone in basic salt solution medium as nitrogen source,fermentation broth ad-dition 6 ml,and static culture at 26 ℃ for 5 d.Under these conditions,the filter paperase and the carboxymethyl cellulase activities reached 2.81 U/g and 10.15 U/g,respectively,which were 1.41 and 1.46 times that of before optimization,and were extremely higher than that of Penicillium oxalicum EU2101 and EU2106 under the same conditions(P＜0.01),indicating that the strain BW-6 had the potential for industrial application.In addition,the optimal reaction temperature and pH of the cellulase produced by strain BW-6 were 50 ℃ and 4.0,respectively,and it was stable at 45 ℃ and pH 5.5-6.0.
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