一株桑枝纤维降解菌株的鉴定及纤维素降解能力测定  

Identification of a Mulberry Branch Fiber Degrading Fungal Strain and Determination of Its Cellulose Degrading Activity

作　　者：褚衍亮[1] 王娜[1] 余晗[1] 

机构地区：[1]江苏科技大学生物技术学院,江苏镇江212018

出　　处：《蚕业科学》2015年第1期127-133,共7页ACTA SERICOLOGICA SINICA

摘　　要：利用高产纤维素酶微生物分解桑树枝条中的木质纤维素,有益于桑枝条资源的高效开发利用。采用刚果红染色法,将分离自桑园土壤的菌株经羧甲基纤维素钠（CMC-Na）培养基初筛和桑枝粉培养基复筛后,获得1株能产生纤维素酶的真菌菌株PTY1。PTY1菌株能够在以桑枝粉末为碳源的培养基中良好生长,最适生长p H为6,最适生长温度为32℃。基于形态和18S r DNA序列鉴定PTY1为烟管菌（Bjerkandera adusta）。该菌株产生的纤维素酶类呈现较高的滤纸酶（FPAase）、羧甲基纤维素酶（CMCase）和β-葡萄糖苷酶活性,其中FPAase在发酵第8天的活力最高,可达5.466 U/m L,CMCase在发酵的第6天和第10天出现2个活力小高峰,β-葡萄糖苷酶活力总体较高,发酵第8天活力最高为12.220 U/m L;FPAase最适反应温度为40℃,最适反应p H为5.5,而CMCase在50℃、p H 4.5-5.5时活力较高,均为酸性酶;以CMC-Na为底物时PTY1菌株酶促反应的Km为0.676 mg/m L,Vmax为0.038 9 mg/（m L·min）。PTY1菌株经过诱变处理后,有望成为降解桑枝纤维素的专用菌株。In order to fully utilize mulberry branch resource,the fungal strains which have high efficiency in yielding cellulase were used to degrade lignocellulose in mulberry branches. Through primary screen with carboxymethyl cellulose sodium（ CMC-Na） medium,and rescreen with mulberry branch powder culture medium,a cellulose-producing fungal strain PTY1 was isolated from mulberry field soil using Congo red staining method. PTY1 strain grew well in medium using mulberry branch powder as carbon source. The optimal growth p H value and temperature was 6 and 32 ℃ respectively.Based on morphology and 18 S r DNA sequence,PTY1 strain was identified as Bjerkandera adusta. The cellulase produced by PTY1 strain has high activity of filter paper enzyme（ FPAase）,carboxymethyl cellulase（ CMCase） and β-glucosidase. The highest activity of FPAase was up to 5. 466 U / m L on the 8th day of fermentation. CMCase activity appeared two small peaks on the 6th and 10 th day of fermentation. β-glucosidase activity produced by PTY1 strain was relatively high and up to 12. 220 U / m L on the 8th day of fermentation. The optimal growth temperature and p H value for FPAase was 40 ℃ and 5. 5 respectively. CMCase activity was relatively higher under the conditions of 50 ℃ and p H 4. 5to 5. 5,showing that it is an acidic enzyme. When CMC-Na was taken as substrate,Kmand Vmaxof CMCase enzymatic reaction was 0. 676 mg / m L and 0. 038 9 mg /（ m L·min） respectively. After mutagenic treatment,PTY1 strain is expected to become the specialized fungal strain for degrading mulberry branch fiber.

关 键 词：纤维素酶 PTY1菌株 烟管菌 酶学特性 降解活性 桑枝条 

分 类 号：X172[环境科学与工程—环境科学]