降解半纤维素嗜热菌的筛选及其酶学性质

以半纤维素为惟一碳源,从温泉中分离到1株降解半纤维素酶的嗜热菌DT-1,经16S rDNA序列比较分析,初步鉴定该菌株属于Geobacillus thermocatenulatus.菌株DT-1发酵条件的初步研究表明:在培养基初始pH为5.0,温度为55℃,装液量为30%,摇床转速为120 r.min-1的条件下培养36 h,该菌株产酶总活力达到最大.对菌株DT-1所产半纤维素酶的性质分析表明:该酶的最适作用温度为65℃,最适作用pH为6;另外,2-ME、EDTA、SDS、PMSF在不同程度上能增强酶的活性,其余抑制剂和去污剂DDT、Tween-20和TritonX-100对该酶活力影响不大;金属离子Mg2+、Ca2+、Mn2+、Fe2+、Co2+对该酶有激活作用,K+、Na+、Li+、Zn2+、Ba2+对酶作用不显著.

Screening of thermophilic bacteria degrading hemicellulose and characterization of hemicellulase

Using the hemicellulose as the sole carbon resource,a thermophilic bacteria DT-1 degrading hemicellulose was isolated from hot spring.Based on the 16s rDNA sequence analysis,the strain was identified as Geobacillus thermocatenulatus.Fermentation conditions of the extracellular enzyme secreted by strain DT-1 were researched.The results showed that in the conditions that initial pH of culture medium was 5.0,culture temperature was 55 ℃,culture-broth-quantum was about 30%,speed of shake-culture was 120 r·min-1,and culture time was 36 hours,the total enzyme activity secreted by strain DT-1 reached its peak.The optimum condition for the enzyme secreted by strain DT-1 was 65 ℃ and pH 6.0.The activity of hemicellulase was enhanced by 2-ME,EDTA,SDS and PMSF,while its activity was decreased slightly by other inhibitors and detergents(DDT,Tween-20 and TritonX-100).Its activity was increased in the presence of Mg2+,Ca2+,Mn2+,Fe2+,Co2+,but its activity decreased when Cu2+,Pb2+,Hg2+,Ni2+,Fe3+,Al3+ were used.