纤维素酶的液体发酵

用液体发酵对11株纤维素酶产生苗的产酶时间和水平进行了比较，两株里氏木霉、两株康氏木霉和一株土曲霉产纤维素酶活力较高，试验菌株的产酶高峰期除EBGA为8．5天少，其余酶均在11．5天以上。对产酶活力较高的两株菌进行了诱导底物和添加物试验，结果表明，未处理过的一些木质纤维素（稻草粉、麦秸粉和玉米芯粉等）对康氏木毒有明显的作用，稀土微肥在实验条件下没有明显的效果。     

高效协同酶解中性汽爆玉米秸秆的工艺优化

玉米秸秆是我国主要的农业废弃物之一,在木质纤维素乙醇领域具有广阔的应用前景。而玉米秸秆预处理和酶法糖化成本过高是目前工艺中的重点和难点之一。从4种纤维素降解酶制剂中优选出对中性汽爆玉米秸秆有最佳协同效果的木霉和黑曲霉纤维素酶制剂（6∶4体积比混合）。在此基础上,评估了木聚糖酶、β-葡萄糖苷酶、β-葡聚糖酶、漆酶、锰过氧化物酶等酶制剂,聚乙二醇-4000、吐温-80、牛血清白蛋白等非酶因子对糖化效率的影响,得到了一组高效协同降解汽爆玉米秸秆的复合酶体系,并获得了适宜的糖化工艺。结果表明,以每克中性汽爆预处理的玉米秸秆为底物,加入10FPU木霉/曲霉混合酶液,并添加1000IU的木聚糖酶和0.05 g PEG4000,于50℃/150 r·min^-1相似文献   

一株纤维素降解菌分离鉴定及其活性初步测定

利用滤纸诱导法从富含腐木土壤中分离得到一株具有纤维素降解活性的真菌菌株,用三点接种法及插片法和CYA鉴别培养基对其进行形态学鉴定,并测定了其发酵滤液的CMC酶活和其对稻草的降解效果。经鉴定该菌为土曲霉原变种(Aspergillus terreus var.terreus);28℃,180 r/min条件下,发酵8 d时,发酵原液的CMC酶活为11.057 U/m L;接种该菌21d的稻草中的纤维素含量由接种前的30.20%分别减少至24.82%。结果表明土曲霉具有一定的纤维素降解能力。     

獐牙菜苦苷的生物转化研究

利用黑曲霉、米曲霉、康氏木霉、短乳杆菌和大肠杆菌体外转化獐牙菜苦苷.色谱分析结果表明,黑曲霉、米曲霉、康氏木霉能有效地转化獐牙菜苦苷,其中以黑曲霉的转化能力最强,转化率达到36%;短乳杆菌和大肠杆菌没有可见的转化反应.从黑曲霉转化液中分离得到了两个转化产物,分别为红百金花内酯和(Z)-5-Ethylidene-8-hy...     

碳源和氮源对纤维素木聚糖复合水解酶合成的影响

以富含纤维素和半纤维素的农副产物玉米芯为发酵底物,以实验室中绿色木霉为产酶菌种纤维素,进行木聚糖复合水解酶的诱导合成研究。结果表明:碳源和氮源种类、浓度及碳氮比等因素对纤维素酶和木聚糖酶的合成都有影响。合成的最佳条件是以经过1%NaOH预处理的玉米芯为主要碳源和诱导物,碳源浓度为20 g/L,利用蛋白胨+硫酸铵+尿素为复合氮源,控制碳氮比为5.6。     

木霉及其混合培养酵母和曲霉产生的纤维素酶系的比较研究

应用盘状聚丙烯酸胺凝胶（PAGE）电泳对绿色木霉A10及其混合培养碑酒酵母和曲霉所产生的纤维素酶进行了初步研究。通过凝胶段切割没提酶液分析表明，混合培养，特别是混合培养曲霉时有较多的同工酶带和较高的酶活力，说明混合培养法提高酶活性是活化调节基因和共生菌产酶协同作用的结果。     

柄篮状菌与里氏木霉酶解棕榈纤维效果的比较

以青霉属柄篮状菌和里氏木霉Rut-C30为研究对象,在50 IU/g底物酶用量的条件下,比较研究了这两种菌株各自对棕榈空果串纤维的酶解能力。结果表明,柄篮状菌对纤维素的酶解能好于Rut-C30,96 h后,两者葡萄糖转化率为83.7%、61.7%。Rut-C30对木聚糖的酶解能力相对较好,其木糖转化率为98.3%,而柄篮状菌酶解的木糖转化率仅为33.1%。将两菌株的酶按1∶1酶用量混合后,棕榈纤维的整体水解效果增强,葡萄糖、木糖转化率依次为91.3%和98.1%。该研究为柄篮状菌与木霉混合水解棕榈纤维提供了依据。     

麸皮对里氏木霉Rut C-30产 纤维素酶的促进作用

本研究尝试通过里氏木霉Rut C-30添加适量的麸皮以及利用实验设计软件Design-Expert寻找适宜的麸皮与微晶纤维素的配比来研究麸皮对里氏木霉Rut C-30产纤维素酶的影响.结果表明,适当的麸皮添加量能够促进纤维素酶的生产;通过二元二次正交旋转组合设计,确定了微晶纤维素添加量和麸皮添加量分别为12.23和23.50 g/L的优化产酶条件.此条件下,在250 mL摇瓶中滤纸酶活达到6.383 FPIU/mL,得率系数为521.913 FPIU/g;在.5 L发酵罐中,滤纸酶活为6.80 FPIU/mL,得率系数为556.582 FPIU/g.相比于优化前,优化后摇瓶实验和发酵罐实验中滤纸酶活分别提高了14.24%和1.403%.而纤维素酶的得率系数却分别降低了6.584%和4.005%.分别以酸解杨木残渣和蒸汽爆破杨木浆替代微晶纤维素作为碳源,最终获得最高滤纸酶活1.953 FPIU/mL和1.45 FPIU/mL.     

拟康氏木霉S—38中纤维素酶的动力学研究

采用动力学的方法研究了等温条件下PH值变化对拟康氏木霉中两个外切酶（CBHⅠ，CBHⅠ）和一个内切酶（EGⅠ）动力学参数的影响。结果表明，EGⅠ游离酶的pKe1及pKe2分别为4．4和5．7，EGⅠ酶—底物复合物的pKes1及pKes2分别为3．6和5．5；外切酶CBHⅠ的pKe1及pKe2分别为3．6和6．3，pKes1及pKes2分别为3．4和6．0；外切酶CBHⅡ的pKe1及pKe2分别为3．6和6．2，pKes1及pKes2分别为3．4和5．9。这些结果说明纤维素酶中存在两个羧基或一个羧基和一个咪唑基参与酶的催化反应，这种机制和溶菌醇是相似的。     

里氏木霉Rut-C30产纤维素酶培养基优化及其酶解特性

以廉价的工业纤维素诱导里氏木霉Rut-C30产纤维素酶,并对液体深层发酵培养基进行优化,采用响应面中心组合设计,以滤纸酶活为响应值,考察工业纤维素、麦麸、大豆粉浓度对纤维素酶活的影响. 结果表明,优化后的培养基组成为：工业纤维素35.62 g/L、麦麸19.37 g/L、大豆粉38.49 g/L,该条件下滤纸酶活达9.13 IU/mL,比优化前提高了72.26%,葡萄糖苷酶酶活提高了80.39%. 在121℃下用2% NaOH对玉米秸秆预处理45 min,物料中纤维素含量达64.94%,用该粗酶液酶解后酶解得率为94.68%.     

康宁木霉SMF2分生孢子及胞外代谢产物的急性毒理

对康宁木霉SMF2的胞外代谢产物及分生孢子进行了小白鼠急性经口毒性试验,家兔皮肤刺激试验及眼刺激试验。试验结果表明,康宁木霉SMF2胞外代谢产物及分生孢子对小白鼠均为实际无毒;对家兔均无皮肤刺激性;康宁木霉SMF2胞外代谢产物对家兔无眼刺激性,而分生孢子则有轻度眼刺激性。试验为康宁木霉SMF2作为绿色生物农药的广泛使用提供了安全依据。     

康氏木霉的原生质体诱变

康氏木霉作为出发菌株,用溶壁酶对菌丝体进行破壁,提取原生质体再用紫外线做诱变处理,经多次筛选,从中选出一株酶活较高菌株,其FP酶活为36.2g/minmL,是原菌酶活的2.41倍。     

木霉纤维素酶基因的克隆与表达研究进展

对自然界中能够产生纤维素酶完全酶系的丝状真菌木霉的纤维素酶基因克隆与表达的研究进展进行了综述,主要包括基因克隆,转化载体,以及基因表达等分子生物学方面的研究。     

A lysine sensor for process control

A lysine sensor for process control of lysine fermentation was developed based on a Clark-type electrode in combination with L -lysine-α-oxidase. The enzyme, isolated from Trichoderma viride, was immobilized between a cellulose and a polypropylene foil using a polyurethane resin. Lysine determinations were carried out in a flow-through system as anodic measurements when H₂O₂ was measured and as chathodic measurements when the consumption of O₂ was followed. The sensitivity of the sensor toward other amino acids was determined.     

A study on enzymatic hydrolysis of cellulose in an attrition bioreactor

In the biological conversion of cellulose, a physical or chemical pretrealment proceeds the hydrolysis by an enzyme. The hydrolysis rate however, is slowed down as the active sites in the pretreated substrates are reduced. In this study, attempts were made to use an attrition bioreactor in which the pretreatment and the hydrolysis were carried out at the same time, where higher hydrolysis rales were achieved. Glass beads of 0.3-cm-diameter and sand were used as the milling media in a batch reactor where pure cellulose, Solka Floc BW200 was hydrolyzed by cellulase secreted from a fungus mutant,Trichoderma reesei. The higher rates observed are believed due to the synergistic effects of the size reduction and the conversion of the crystalline to the amorphous form of cellulose which was observed by comparing the X-ray diffractorgrams of the cellulose hydrolyzed in the reactors with and without milling medium. A simple kinetic model was found satisfactory in depicting the hydrolysis mechanism, and the kinetic parameters were estimated. Higher power consumption as compared to a reqular stirred reactor was observed and a quantitative expression was derived for its estimation.     

Production of enzymes from potato pulp using batch operation of a bioreactor

Trichoderma reesei strains MCG77 and Rut C30 were cultivated in batch operation in a stirred tank reactor on potato pulp (PP) consisting of starch, pectin, cellulose, and hemicellulose; potato pulp residue (PR) without starch and pectin; or enzymatic residue (ER), respectively, as substrate and potato protein liquor (PPL) as supplement. The enzyme mixtures produced by the fungi were characterized by four assays: with avicelase, CMCase, xylanase, and FP-activities. Trichoderma reesei Rut C30 yielded higher activities than Trichoderma reesei MCG77. The enzyme activities and productivities obtained with PR are comparable to those obtained by other groups using pure cellulose and a synthetic nutrient solution in batch culture. An optimal operation strategy was derived to obtain maximum enzyme activity and productivity. After converting PR with the enzymes produced and using the residue, ER, as substrate for enzyme production, 85% (w/w) of the pulp was utilized.     

Pentachlorophenylcellulose preparation and investigation on its applicability as a controlled release fungicide

Pentachlorophenylethers (PCP-ethers) of cellulose are prepared using cellulosetosylates as intermediates. The products release no measurable quantities of PCP into buffered solutions (pH 4, 7, and 9, resp.). However, the modified cellulose shows no fungicidal effect in agar plate tests with the usually cellulose-metabolizing fungus, Trichoderma viride. The lack of biological activity is attributed to the stability of the cellulose pentachlorophenyl ether bond.     

磷石膏滤饼再浆（酸化）水洗的降磷效果及实践中再认识

磷石膏中P2O5含量是磷石膏能否被建材工业利用的控制指标之一。对湿法磷酸生产流程中串联再浆(酸化)水洗的降磷效果进行了实验研究。实验结果:水溶性磷大幅降低,酸洗时不溶性P2O5有所下降,但磷石膏的晶间P2O5保持不变,处理后的磷石膏质量指标均不满足标书要求,不难理解国际上高质量的磷石膏多数是通过再结晶获得。在再浆的磷酸装置,由于80%被磷石膏带走的钾、钠盐,通过再浆大部分又返回磷酸系统,造成磷酸过滤系统出现严重、十分反常的结块现象,文中谈到对此问题的处理办法与思考。