【摘要】 为了研究桦剥管菌木材纤维素降解机制,试验分别于23℃和28℃培养桦剥管菌,用菌落直径比较生长速度;以白桦木屑、云杉木屑和麦麸为底物诱导培养,以不加木屑的马铃薯液体培养基为对照,测定12 d内桦剥管菌在纤维素外切酶和纤维素内切酶两种纤维素酶活变化;以云杉木屑、白桦木屑、玉米秸秆和麦麸为诱导物,测定15~21 d内木聚糖酶和甘露聚糖酶两种半纤维素酶活变化;检测8种不同金属离子以及金属离子抑制剂EDTA对两种半纤维素酶活性的影响;并对白桦木屑诱导桦剥管菌产半纤维素酶的酶学性质进行了初探。结果表明:桦剥管菌菌丝更适合在28℃培养;纤维素外切酶和纤维素内切酶的最适底物分别为白桦木屑和云杉木屑,木聚糖酶和甘露聚糖酶最适底物分别为麦麸和玉米秸秆;两种半纤维素酶的最适反应温度均为50℃,最适反应pH值分别为5.0和6.0;8种金属离子中,仅Co2+对两种半纤维酶活性均有促进作用,EDTA对两种酶活性均具有较强抑制作用。更多还原

【Abstract】 To study the degradation mechanism of wood cellulose with Piptoporus betulinus( P. betulinus),their growing speeds were compared when the fungi were cultured at two different temperatures including 23 ℃ and 28 ℃,respectively. The changes in the activities of exo- cellulase and endo- cellulase were determined within 12 days with birch sawdust,spruce sawdust and wheat bran as substrates to induce the culture while taking the potato liquid medium without sawdust as a control. The changes in the activities of two hemicellulases,xylanase and mannase,were determined during 15 and 21 days taking spruce sawdust,birch sawdust,corn stover and wheat bran as inducers. The effects of eight different metal ions and metal ion inhibitor EDTA on the activities of the two hemicellulases were detected,respectively. The enzymatic properties of the two hemicellulases produced by P. betulinus were also preliminary studied when using birch sawdust as an inducer. The results showed that P. betulinus was more suitable for culturing at 28 ℃. The optimal substrates for exo- cellulase and endo- cellulase were birch sawdust and spruce sawdust,while the optimum substrates for xylanase and mannase were wheat bran and corn stover,respectively. The optimum reaction temperature for the two hemicellulases were all 50 ℃,while the optimum pH values for xylanase and mannase were 5. 0 and 6. 0,respectively.Among the eight metal ions,only cobalt ion could promote the activities of the two hemicellulases,and EDTA had strong inhibitory effect on the activities of the two hemicellulases.更多还原