一株产生内切β-1,4-木聚糖酶的菌株的分离、鉴定及其酶学特性研究

Study on isolation,identification,and enzymatic characteristics of a strain which produce endo-1,4-β-xylanase

内切β-1,4-木聚糖酶作为饲料添加剂可明显改善麦类的营养价值,显著提高畜禽生长速度和饲料转化率;用在纸浆漂白中可减少漂白剂的用量并提高纸张质量。利用透明圈法从长期排放食堂锅炉污水口污泥中筛选分离到一株产内切β-1,4-木聚糖酶的细菌菌株,该菌株菌体呈长杆状、革兰氏染色可变、兼性厌氧、产芽孢(次端生、孢囊膨大),鞭毛周生,命名为A3。据部分片断长度的16SrDNA序列同源性分析和生理生化试验结果,发现分离菌株与浸麻芽孢杆菌(Bacillusmacerans)最为相近。A3菌株所产内切β-1,4-木聚糖酶的最适反应温度为60℃,最适反应pH为5.0～7.0,pH7.0条件下该酶在50℃下稳定,40℃条件下该酶在pH4.0～10环境中相对稳定。

Endoβ1,4xylanase as feed additive can markedly improve the nutrition of barley, and thus enhance animals' growth rates and transformation rates of feed. The enzyme can reduce the rates of bleacher and improve the quality of papers when it was used in bleaching paper pulp. A bacterial strain, which is capable of producing endoβ1,4xylanase, was isolated from soils that was contaminated by discharged water from boilers of dining rooms with a method based on transparent ring. The strain, named A3, was Grampositive becoming Gramnegative with increasing age, facultative anaerobe, sporeforming and peripheral flagella rods. It was found mostly similar to Bacillus macerans based on the results of physiobiochemical identification and the phylogenetical analyses of 16S rDNA sequence. The phylogenetic position of the A3 strain also was performed. The endoβ1,4xylanase from culture supernatant of A3 was optimally active at 60℃ and pH5.0-7.0. It was thermostable at 50℃ and comparatively stable in the condition of pH 4.0-10.0.