Inducement of β-glucanase from Trichoderma harzianum UN-2 and its antifungal and preventive effects on rice sheath blight
[Objective]The present paper aimed to optimize the medium composition and fermentation parameters of Trichoderma harzianum strain UN-2 producingβ-glucanase,improve its β-glucanase production capacity,and study the antagonism of the crude enzyme solution ofβ-glucanase on the pathogen of rice sheath blight and its field control effect,so as to clarify the application potential of T.harzianum strain UN-2 in controlling rice sheath blight.[Method]In order to optimize the inducing conditions for the production of β-glucanase from T.harzianum strain UN-2,a single factor experiment was conducted to investigate the effects of carbon,nitrogen and metal ions on the production ofβ-glu-canase from T.harzianum strain UN-2,and orthogonal experiments were used to determine the optimal temperature,pH,inoculation amount,bottled amount,shaking speed,and fermentation time for the production of glucanase from T.harzianum strain UN-2.The antifungal and pre-ventive effects of crude β-glucanase solution on rice sheath blight were studied through in vitro antagonism and field experiments.[Result]The optimal carbon and nitrogen sources for the fermentation of β-glucanase from T.harzianum strain UN-2 were wheat bran and ammonium sulfate,respectively.Metal ions Ca2+ and Mg2+ had a significant promotional effect on the activity of β-glucanase induced from T.harzia-num.The optimal culture medium for T.harzianum strain UN-2 to produceβ-Glucanase were composed of 10.0 g/L wheat bran,0.5 g/Lβ-glucan,4.0 g/L ammonium sulfate,1.5 mmol/L Ca2+,0.5 mmol/L Mg2+.And the optimal fermentation conditions for producing β-glu-canase were as follows:30 mL medium filled in 250 mL flask with 8 mL inoculum amount of the culture,initial pH 6.5,at 32 ℃,with shaker speed 160 r/min,incubating for 64 hours.The crude β-glucanase solution induced from T.harzianum strain UN-2 had a significant inhibito-ry effect on the mycelial growth and sclerotia germination of Rhizoctonia solani and Rhizoctonia cerealis,and the field control effect on rice sheath blight caused by R.solani was 70.45％,which was equivalent to 5％Jinggangmycin treatment.The crude β-glucanase solution could improve rice seed setting rate and grain plumpness.[Conclusion]Under the optimal fermentation conditions,the activity of β-glucanase in-duced from T.harzianum strain UN-2 is 97.68 U/mL,the crude β-glucanase solution has strong antifungal and preventive effects on rice sheath blight,and has a certain growth promotion effect on rice plants.
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