高产木聚糖酶细菌的筛选、鉴定及其部分酶学特性  

Isolation and identification of a xylanase-producing bacterium and its enzymatic characteristics

作　　者：高志强[1] 李茜[1] 徐岳松 张玮佳[1] 曹毅[1] 乔代蓉[1] 徐辉[1] 

机构地区：[1]四川大学生命科学学院,微生物与代谢工程四川省重点实验室,成都610065

出　　处：《应用与环境生物学报》2017年第3期443-447,共5页Chinese Journal of Applied and Environmental Biology

基　　金：“十二五”国家科技支撑计划项目(2014BAD02B02);四川省科技厅项目(2014GZX0005,2017JCPT0001)资助

摘　　要：细菌木聚糖酶具有优良的酶学特性,发掘和研究高产菌株资源对促进木聚糖酶工业生产具有十分重要的意义.采用刚果红透明圈法从采集的土样样品中筛选分离得到1株高产细菌木聚糖酶的菌株SD4-4,通过形态特征及16S r DNA序列分析进行鉴定,并以本实验室保存的细菌木聚糖酶工业生产用菌枯草芽孢杆菌Bacillus subtilis SL作为对照,对比研究SD4-4的产酶水平及酶学性质.结果表明,SD4-4为短小芽孢杆菌(B.pumilus),利用小麦麸皮摇瓶发酵,其上清酶活可达1 166.0 U/m L,而SL上清酶活为281.0 U/m L.SD4-4所产木聚糖酶作用最适温度约为50℃,最适p H约为5.0.粗酶液在30-50℃的环境下处理10 min,相对酶活均保持在90%以上;在p H 4.0的条件下处理30 min,相对酶活仍有76%,酸性环境下稳定性较好.因此,菌株SD4-4产酶水平高于对照菌株SL,酶学特性更为优良,工业应用前景良好,尤其在饲料添加剂行业具有较大的开发潜力.Xylanase （originating from bacteria） with excellent enzymatic properties has promising prospects for industrial applications. Regretfully, due to a lack of the strain resources, it is important to enrich the collection of xylanase-overproducing bacterial strains and to study the enzymatic properties. The Congo red staining method was used to screen bacteria from soil samples for xylanase-overproducing strains. Next, morphological characteristics and 16S rDNA sequence analysis were used to identify the resulting strain. Bacterial fermentation using wheat bran as a carbon source produced xylanase. The enzymatic activity was determined by the conventional method DNS （dinitrosalicylic acid）. Analysis of the enzymatic characteristics included identification of the optimal pH, optimal temperature, and pH and temperature tolerance. Besides, we compared the screened out strain with the industrial bacterium Bacillus subtilis SL in terms of action on feed additives stored in our laboratory. In this study, the bacterial SD4-4 strain overproducing xylanase was isolated by the Congo red staining method. We identified the SD4-4 strain as Bacillus pumilus by morphological characteristics and 16S rDNA sequence analysis. The enzymatic activity of SD4-4 strain reached 1 166 U/mL in liquid fermentation with wheat bran as a carbon source; the enzymatic activity of a control strain was only 281 U/mL. The optimal pH and temperature of the crude xylanase were approximately 5.0 and 50 ℃, respectively. More than 90% of the enzymatic activity was retained after the enzyme was kept at 30–50 ℃ for 10 min, and 76% of the activity was retained after the enzyme was incubated in a buffer at pH 4.0 for 30 min. The SD4-4 strain has broad application prospects for production of feed additives.

关 键 词：木聚糖酶 16S RDNA 短小芽孢杆菌 枯草芽孢杆菌 酶学性质 

分 类 号：TQ925[轻工技术与工程—发酵工程] Q939.97[生物学—微生物学]