链霉菌XP产耐热木聚糖酶的发酵条件优化及酶解产物鉴定

Optimization of Fermentation Conditions for Producing Xylanase and Identification of Hydrolysate of Xylan by the Xylanase from Streptomyces XP

[目的]对1株产胞外耐热木聚糖酶的链霉菌XP的产酶条件进行优化,并对其降解木聚糖的产物进行鉴定。[方法]分别对该菌摇瓶发酵产酶的培养基组成、培养基初始pH值、发酵温度、发酵时间、装液量进行了优化,并以燕麦木聚糖为底物,采用薄层层析法考察了粗酶对底物的水解产物组成。[结果]该链霉菌的液体发酵产酶的最佳培养基为:稻草3.0%,NaOH0.2%,KH2PO40.5%,(NH4)2SO40.5%,培养基起始pH值为7.5,发酵温度37℃,发酵时间72h,摇床转速190r/min,250ml的三角瓶装液量为60ml。用该菌产生的胞外粗木聚糖酶酶液酶解燕麦木聚糖,降解产物主要为木二糖和木三糖,没有产生单木糖。[结论]该研究为木聚糖酶生产菌株的研发提供了一定的技术参考,酶解产物表明该酶在低聚木糖的制备中有很大的应用价值。

[Objective] The study aimed to optimize the fermentation conditions for producing xylanase by Streptomyces XP,and identify the hydrolysate of xylan by the xylanase from this strain.[Method] The media composition,initial pH value of the media,fermentation temperature,fermentation time,liquid loaded volume for producing xylanase of this bacteria by using flask fermentation were optimized.Taking xylan from oats as substrate,the hydrolysate of the substrate by using crude enzyme was investigated by using TCL method.[Result] The best medium for producing xylanase from Streptomyces XP by using liquid fermentation was composed of 3.0% straw,0.2% NaOH,0.5% KH2PO4,0.5% （NH4）2SO4.The initial pH value of the medium was 7.5,fermentation temperature was 37 ℃,fermentation time was 72 h,liquid volume was 60 ml in 250 ml triangle bottle,the rotating speed was 190 r/min.After xylan from oats was hydrolyzed by extracellular crude xylanase form Streptomyces XP,the major hydrolyastes of xylan by this enzyme displayed on TCL were xylotriose and xylibiose.And none xylose was found.[Conclusion] This study provided some technical reference for the research and development of producing xylanase strain.The hydrolyaste of xylan by this enzyme suggested that the enzyme had great value in the preparation of xylo-oligosaccharide.