大曲复合酶系对小麦协同降解作用研究

Synergistic degradation of wheat by Daqu complex enzyme system

为研究大曲复合酶系对天然底物小麦的降解作用,采用异源表达法和亲和层析法纯化来自浓香型白酒大曲的内切淀粉酶(NFAmy13B、NFAmy13A)、内切葡聚糖酶(NFEg16A)和来自Thermoanaerobacterium bryantii mel9T的木聚糖酶(TbXyn10A)及木糖苷酶(TbXyl39A、TbXyl52A)。以小麦粉碎物为底物,研究不同酶及配比对小麦降解的影响,并通过对羟基苯甲酸(p HBAH)法测定还原糖含量评估降解效果。结果表明,NFAmy13B是典型的液化淀粉酶,可高效降解长链淀粉,其4 h降解小麦粉碎物得到的还原糖含量为5.12 mmol/L。NFAmy13A是典型糖化性淀粉酶,可高效将短链淀粉降解为麦芽糖,NFAmy13A和NFEg16A可以提高NFAmy13B的降解效率,复配水解效率为NFAmy13B的2.6倍。木聚糖酶和木糖苷酶与NFAmy13B、NFAmy13A、NFEg16复配可进一步提高小麦降解效率,复配水解效率为NFAmy13B的2.9倍。该研究证实大曲复合酶系对小麦粉碎物存在协同降解作用。

To study the degradation of the Daqu complex enzyme system on the natural substrate wheat,twoα-amylases(NFAmy13B and NFAmy13A),endo-β-glucanase NFEg16 from strong-flavor(Nongxiangxing)Baiju Daqu,as well as xylanase TbXyn10A,and two xylosidases(TbXyl39A and TbXyl52A)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 evaluated by measuring the content of reducing sugar by p-hydroxybenzoic acid(pHBAH)method.The results shown that Daquα-amylases NFAmy13B was a typical liquefyingα-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 maltogenicα-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.