Synergistic degradation of wheat by Daqu complex enzyme system
To study the degradation of the Daqu complex enzyme system on the natural substrate wheat,two α-amylases(NFAmy13B and NFAmy13A),endo-β-glucanase NFEg16 from strong-flavor(Nongxiangxing)Baiju Daqu,as well as xylanase TbXyn10A,and two xylosidases(TbXy139A and TbXy152A)from Thermoanaerobacterium bryantii mel9T,were heterologouly expressed and purified using affinity chromatography methods.Using wheat crushing material as substrate,the effects of different enzymes and ratios on wheat degradation were studied,and the degradation effect was eval-uated by measuring the content of reducing sugar by p-hydroxybenzoic acid(pHBAH)method.The results shown that Daqu α-amylases NFAmy 13B was a typical liquefying α-amylase,which could efficient degrade long-chain starch,and produced 5.12 mmol/L reducing glucose by degrading wheat powder for 4 h.NFAmy13A was a typical maltogenic α-amylase,which could efficient degrade short-chain starch into maltose,and together with NFEg16A,significantly improved the degradation of NFAmy13B on wheat powder,with their compound hydrolysis efficiency being 2.6 times that of NFAmy13B alone.Combining xylanase and xylosidase with the former three enzymes could further improve wheat degradation,achieving 2.9 times that of NFAmy13B alone.This study confirmed that Daqu complex enzyme system had synergistic degradation effect on wheat powder.
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