木聚糖酶生产菌Saccharothrix variisporea YJ的筛选、发酵条件及酶学性质研究

Screening,Fermentation Conditions and Enzymatic Properties of Xylanase Producing Strain Saccharothrix variisporea YJ

以Azo-xylan为底物,利用双层平板法从堆肥中筛选到可降解木聚糖的菌株,16S rRNA测序分析显示该菌株与糖丝菌属(Saccharothrix variisporea)的同源性最高(99.33%),命名为S.variisporea YJ。研究发现以酵母提取物或(NH4)2SO4作为氮源、甘蔗叶作为碳源、初始pH值7.0、发酵温度40℃、发酵时间5 d时,发酵液中木聚糖酶的酶活性最高。酶学性质研究表明该木聚糖酶的最适反应温度及pH值分别为55℃和8.0,在55℃以下及pH值4.0~10.0的范围内保持较高稳定性。Na+能有效提高木聚糖酶活性,Mg^(2+)和Mn^(2+)没有明显影响,Cu^(2+)则严重抑制木聚糖酶活性。此外,发酵液还可以直接对天然底物玉米芯进行降解。

Azo-xylan as substrates,biodegradable xylan strain was screened from compost by double-layer plate method,16S rRNA sequencing analysis showed that the strain had the highest homology with Saccharothrix variisporea(99.33%)the strain was then named as Saccharothrix variisporea YJ.The study had found that when yeast extract or(NH4)2SO4was used as nitrogen source,sugarcane leaf as carbon source,initial pH at 7.0,fermentation temperature at 40℃and fermented for 5 d,xylanase activity from fermented broth was the highest.Enzymatic properties studies showed that the optimal reaction temperature and pH of the xylanase were 55℃and 8.0,respectively,and maintained high stability below 55℃within pH 4.0~10.0.Na+could effectively improve the activity of xylanase,while Mg^(2+)and Mn^(2+)had no significant effect,and Cu^(2+)severely inhibited xylanase activity.In addition,the fermentation broth can directly degrade corn cob,a natural substrate.