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RutC-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RutC-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23．50g/L的优化产酶条件：此奈件下,在250mL摇瓶中滤纸酶活达到6．383FPIU／mL,得率系数为521．913FPIU／g;在7．5L发酵罐中,滤纸酶活为6．807FPIU／mL,得率系数为556．582FPIU／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14．247％和17．403％,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1．953FPIU／mL和1．745FPIU／mL。     

木聚糖成分对木聚糖酶合成的影响

分别以两种含有不同组成的木聚糖为碳原进行产酶研究,结果发现木聚精成分对里氏木霉产木聚糖酶的效果具有重大影响。实验结果表明,用全组分的木聚糖（即用酒精等有机溶剂沉淀下来的木聚糖）诱导合成本聚糖酶的效果要比仅以水不溶性高聚合度木聚糖的效果好。当以全组分的木聚糖为碳源产酶时,不仅产酶周期缩短（仅需2．5d）,而且有利于提高木聚糖酶活力,酶活力、比活力、酶得率及酶产率分别达到34．27IU／mL、78．21;IU／g蛋白质、4895．7IU／g木聚糖和13708．0IU／L·d,酶活力和酶产率分别是以水不溶性木聚糖为碳源时的2．7倍和3．3倍。     

低聚合度木聚糖对木聚糖酶合成的影响

研究了木聚糖的聚合度和添加黄豆粉对里氏木霉合成木聚糖酶的影响，并以纯化木聚糖酶水解木聚糖。研究结果表明：木聚糖经酶水解后平均聚合度降低54％，戊聚糖含量为75．4％。采用低聚合度木聚糖为底物碳源和添加黄豆粉都可提高产酶效果。以12g／L低聚合度木聚糖添加2g／L黄豆粉，培养3d后木聚糖酶活力可达到113IU／mL，提高49．3％。通过对木聚糖酶进行纯化处理可以有效除去β-木糖苷酶。以体积分数10％的木聚糖酶水解35g／L木聚糖3h后，低聚木糖得率达到35．5％，而木糖得率仅为1．5％，低聚木糖与总糖的比值达到95．8％，随着酶解时间的延长，低聚木糖不会被降解。     

低聚木糖生产用里氏木霉木聚糖酶选择性合成的研究现状

对低聚木糖生产用里氏木霉木聚糖酶选择性合成的研究现状进行了较全面的总结和评述。系统地介绍了里氏木霉木聚糖酶的的多样性以及碳源、pH和碳氮比等培养条件对合成内切木聚糖酶和木糖苷酶的影响,提出了调控这些培养条件选择性合成低木糖苷酶活的木聚糖酶的方法。     

粗糙脉孢菌(Neurospora crassa)木聚糖酶的合成及性质研究

粗糙脉孢菌1602(Neurosporacrassa)可以产生木聚糖酶。以不同的植物纤维物料及纯木聚糖作为底物都可诱导产生较高的木聚糖酶活,其中玉米芯粉的诱导能力最强,酶活可达25.02IU/mL。纤维素与木聚糖混合对木聚糖酶合成具有促进作用。葡萄糖、木糖对木聚糖酶的合成有很强的阻遏作用,葡萄糖的阻遏作用大于木糖的阻遏作用。其木聚糖酶最适作用pH值为5.4,最适作用温度为60℃。     

直接降解木质素的漆酶/木聚糖酶体系的合成

对一株高产漆酶及伴有木聚糖酶和少量纤维素酶的菌株,用不同的碳源和氮源对其调控培养,合成漆酶/木聚糖酶体系。实验结果表明,最佳的碳源是可溶性淀粉,用它作碳源,漆酶活性高达730IU/mL,木聚糖酶活性是4.49IU/mL,纤维素酶活性只有0.23IU/mL;最佳的氮源是蛋白胨,用其作氮源,合成漆酶活性可达812IU/mL,木聚糖酶活性是4.68IU/mL,纤维素酶活只有0.09IU/mL。     

绿色木霉高效纤维素酶菌株的选育

采用NTG和UV连续处理绿色木霉IFO31137菌株（TTichodermaviTideIFO31137），并对菌株纤维素酶活力和酶吸附率作双重比较，获得突变株SO－465。其微晶粉末纤维素酶（Avicelase）活力提高8．2倍，酶对废物的吸附率增加约5倍。突变菌株对四种纤维素底物（微晶粉末纤维素、滤纸、纸浆纤维和KCFloc）的水解率分别为87．5％、81．9％、90．5％和83．2％，比原始菌株增加幅度为101％、230％、83％和74％。     

不同培养条件对云芝(Coriolus versicolor)木质素降解酶产酶影响的研究

本文研究了不同培养条件对云芝（Coriolusversicolor）三种木质素降解前产酶的影响，发现三种木质素降解酶即水质素过氧化物酶（Lip）、赖锰标木质素过氧化物酶，（Mnp）和漆酶的产生和培养条件关系很大，添加黎芦醇（VOH）能显著地提高三种酶的产量，当VOH浓度为1mmol／L时，可使木质素过氧化物酶产量提高10倍，添加Mn2＋对赖锰木质素过氧化物酶有促进作用，但对木质素过氧化物酶有抑制作用。提高其它微量元素（Cu2+，Fe2+,Zn2+，Ca2+）等同样能显著促进三种酶的产生。采用30信浓度时，赖锰木质素过氧化物酶的量要比1培浓度时提高6倍。三种酶的最适产酶pH相差很大，木质素过氧化物酶在pH4．5～5．5左右，赖锰木质素过氧化物酶在PH5．5～6.5左右，而漆酶则抵达pH3．5～4．0．Tween80在低浓度时（0.01％-0.02％）有一定的促进作用，而在高浓度则有抑制作用。C／N比则是影响产酶的另一因素，低碳培养基比低氮培养基更适宜三种木质素降解酶的产生。同时，在低氮培养基和低碳培养基下，上述因素对三种酶产生的影响也存在显著差异。这有可能是云芝的木质素降解酶在不同的C／N下其产生机理存在差异。     

超滤分离里氏木霉木聚糖酶的研究

研究了进料速度、操作压力、木聚糖酶活大小对内切-β-木聚糖酶和β-木糖苷酶超滤分离的影响。结果表明,用超滤的方法可以将内切-β-木聚糖酶和β-木糖苷酶很好地分离,内切-β-木聚糖酶活的收率随着进料速度的提高而增加,当进料速度从 300mL/min 提高到 450 mL/min 时,内切-β-木聚糖酶活的收率从 79.21%提高到 91.35%;内切-β-木聚糖酶活的收率随着操作压力的提高而降低,当操作压力从 4 kPa 提高到15 kPa 时,内切-β-木聚糖酶活的收率从 89.91%下降到 66.48%,而且操作压力越大越容易阻塞超滤膜;内切-β-木聚糖酶活的收率随着酶活的降低而增加,当总木聚糖酶活一定时,木聚糖酶活从 45.18 IU/mL 下降到 22.59 IU/mL 时,内切-β-木聚糖酶活的收率从 82.63%提高到 89.91%,木聚糖酶活较低时,酶液的体积增大,超滤时间过长,也会导致内切-β-木聚糖酶活收率降低。因此,在木聚糖酶活较低的情况下(酶活为22.59 IU/mL),温度为 25℃时,内切-β-木聚糖酶和β-木糖苷酶的适宜的分离条件为:压力为 4 kPa,进料速度为 450 mL/min,内切-β-木聚糖酶活的收率为 91.35%。     

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.     

小球藻在蔗渣酶解液中的异养生长及其脂肪酸生成

在高温液态水处理的甘蔗渣酶解过程中添加Tween80可使聚糖转化率提高11.4%。根据蔗渣酶解液中糖的种类及含量,用葡萄糖、木糖和纤维二糖标准品模拟蔗渣酶解液组成配制成相应的混合糖培养基,同时配制仅含葡萄糖的培养基,在有、无Tween80和BG11(Blue-Green 11)的条件下,考察小球藻在不同培养基中的异养生长及脂肪酸生成。结果显示Tween80对小球藻的生长具有抑制作用,纤维二糖也会影响小球藻的生长;小球藻在添加BG11的葡萄糖培养基中的生物量最高,为1.97 g·L^-1,在添加BG11的蔗渣酶解液中的生物量高出未添加BG11的2倍,在含有Tween80和BG11的蔗渣酶解液中的总脂肪酸含量最高,达到6.90%,在所有培养基中产生的脂肪酸以C_16:0、C_18:1、C_18:3、C_20:1和C_20:4为主;培养基组成优化可进一步提高微藻生物量和油脂产量。     

不同发酵条件下Tween80对 乳酸链球菌SM526产Nisin的影响

以SYS3为发酵培养基,研究了在不同发酵条件下Tween80对乳酸链球菌SM526产Nisin的影响.在自然pH、兼性厌氧发酵条件下,在体积浓度0 1%的范围内,乳链菌肽的活性随Tween80浓度的提高而提高,最适浓度(1%)时,提高幅度为36%;浓度超过1%后, Nisin的活性有所降低.在兼性厌氧条件下通过流加NaOH溶液保持恒定pH为 6.5并添加1%的Tween80进行发酵,同不添加Tween80相比,发酵单位提高了30%.在厌氧条件下恒定pH为6.5并添加1%的Tween80进行发酵,同不添加Tween80相比,发酵单位提高了17%.     

Xylanase production by Bacillus polymyxa

Bacillus polymyxa produced high levels (12–13 U cm^?3) of extracellular xylanases when grown in a complex medium containing yeast extract and oat spelt xylan as nitrogen and carbon sources respectively. Substantially lower yields of enzyme were produced during growth on the monosaccharides glucose, arabinose and xylose. Meagre growth occurred when ammonium sulphate, instead of yeast extract, was used as nitrogen source. When assayed in culture broth supernatants, xylanase showed an optimum activity in 48°C and at pH values in the range 5.0–6.5. Under such conditions, the half-life of this xylanase preparation was 8 h. Mn²⁺ showed a strong inhibitory effect on the enzyme, but inhibition by EDTA (27% w/v) suggested dependence on a metallic ion. SDS-PAGE and zymogram overlay showed that up to five separate xylanases in the range of 20 to 116 kDa were produced.     

Characterization of cellulase and xylanase activities of Clostridium celerecrescens

The production of cellulases and xylanase by Clostridium celerecrescens, a new anaerobic mesophilic cellulolytic bacterium, was studied using various substrates (cellobiose, xylan and cellulose Whatman CF-11). While both cellulase (β-1,4-D-glucan glucanohydrolase) and xylanase (β-1,4-xylan xylanohydrolase) were produced on cellulose, only the latter was produced when xylan was used as the sole carbon source. A weak p-nitrophenyl-β-D cellobiohydrolase activity was detected in the extracellular filtrates when using cellulose as a substrate. Otherwise, β-glucosidase (p-nitrophenyl-β-D-glucopyranosidase) was always found to be associated with the bacteria and reached its maximum levels of growth on cellobiose. In all cases, enzyme production showed a cell growth associated profile. Activities of these enzymes had their optimal values within the ranges of temperature and pH reported for the corresponding enzymes from similar anaerobic mesophilic microorganisms, although a relatively high optimum temperature, 55°C, was found for xylanase. All enzymes showed a 90% reduction of half-life time for each 8°C increment of temperature. A 50% inhibition of xylanase and β-cellobiohydrolase activity was observed, through a competitive mechanism, by xylose (0.677 mmol dm^?3) and cellobiose (28 mmol dm^?3) respectively.     

Effect of LHW,HCl, and NaOH pretreatment on enzymatic hydrolysis of sugarcane bagasse: sugar recovery and fractal-like kinetics

Conversion of lignocellulose to sugars involves two main processes, namely pretreatment and enzymatic hydrolysis. Lignocellulose pretreatment leads to the degradation of enzymatic recalcitrance of substrate for achieving efficient saccharification. In this study, liquid hot water (LHW), hydrochloric acid (HCl), and sodium hydroxide (NaOH) were as reagents used to pretreat sugarcane bagasse (SB). Results showed that LHW, HCl, and NaOH pretreatment could solubilize 95.3%, 94.7% xylan and 88.7% lignin, respectively. Enzymatic hydrolysis of pretreated SB showed that the maximum glucose (26.0?g/L) and xylose (12.7?g/L) concentration were produced by NaOH pretreatment, and slightly more glucose and less xylose were produced after HCl pretreatment compared to LHW pretreatment. Addition of Tween 80 or xylanase could significantly improve both glucose and xylose production. At 48?h, the glucose increase for LHW, HC1 and NaOH pretreatment was 38.3%, 26.4% and 8.0%, respectively, and the xylose increase for them was 35.0%, 24.9% and 1.7%, respectively. Fractal-like kinetics showed that the value of rate constant increased after the addition of Tween 80 or xylanase, and the efficiency of enzymatic hydrolysis mainly depended on rate constant other than fractal dimension of substrate. Totally, substrate accessibility was dominated for efficient of lignocellulose to sugar compared to enzyme loading. The application of fractal-like theory on the heterogeneous enzymatic hydrolysis of lignocellulose was quite successful.     

黑曲霉液体发酵产木聚糖酶的研究

通过单因素实验及响应面方法对黑曲霉菌株产木聚糖酶发酵条件进行了研究,结果表明:当培养基为麸皮40g/L,(NH4)2 SO4 4g/L,KH2PO4 3g/L,MgSO4 0.8g/L,吐温80 1g/L;初始pH值5.0,接种量8.0%,培养温度30℃;此条件下发酵木聚糖酶酶活达1456.27IU/mL。     

重组大肠杆菌生产极端耐热木聚糖酶

将含有来自于嗜热网球菌(Dictyoglomus thermophilum)Rt46B.1编码极端耐热木聚糖酶基因xynB的表达载体pET-DBc转化大肠杆菌(Escherichia coli)BL21(DE3),获得重组菌E. coli DB1,目的基因可表达出有活性且耐90oC的木聚糖酶. 初步优化的E. coli DB1发酵培养基的组成为(g/L)：葡萄糖50,NH4Cl 3,MgSO4 0.5,CaCl2 0.6,Na2HPO4×7H2O 12.8,KH2PO4 3.0,NaCl 0.5. 重组菌E. coli DB1木聚糖酶的耐热特性有利于木聚糖酶的下游回收和提取.     

An approach to optimization of enzymatic hydrolysis from sugarcane bagasse based on organosolv pretreatment

BACKGROUND: The organosolv pretreatment followed by enzymatic hydrolysis of the pretreated material and subsequent fermentation of the hydrolysate produced, was the strategy used for ethanol production from sugarcane bagasse. The effect of different operational variables affecting the pretreatment (the catalyst type and its concentration, and the pretreatment time) and enzymatic hydrolysis stage (substrate concentration, cellulase loading, addition of xylanase and Tween 20, and the cellulase/β‐glucosidase ratio), were investigated. RESULTS: The best values of glucose concentration (28.8 g L^?1) and yield (25.1 g per 100 g dry matter) were obtained when the material was pretreated with 1.25% (w/w) H₂SO₄ for 60 min, and subsequently hydrolyzed using 10% (w/v) substrate concentration in a reaction medium supplemented with xylanase (300 UI g^?1) and Tween 20 (2.5% w/w). Fermentation of the broth obtained under these optimum conditions by Saccharomyces cerevisiae resulted in an ethanol yield of 92.8% based on the theoretical yield, after 24 h. CONCLUSION: Organosolv pretreatment of sugarcane bagasse under soft conditions, and subsequent enzymatic hydrolysis of the pretreated material with a cellulolytic system supplemented with xylanase and Tween 20, is a suitable procedure to obtain a glucose rich hydrolysate efficiently fermentable to ethanol by Sacharomyces cerevisiae yeasts. Copyright © 2010 Society of Chemical Industry     

Effect of tween series on growth and cis-9, trans-11 conjugated linoleic acid production of Lactobacillus acidophilus F0221 in the presence of bile salts

Cis-9, trans-11 conjugated linoleic acid (c9, t11 CLA) producing bacteria have attracted much attention as novel probiotics which have shown beneficial effects on host health. However, bile salts are able to inhibit bacterial growth and c9, t11 CLA production. For recovering growth and c9, t11 CLA production of Lactobacillus acidophilus F0221 in the presence of bile salts, Tween series (Tween 20, Tween 40, Tween 60 and Tween 80) were added in growth culture containing 0.3% oxgall. Results showed that the viable counts were significantly (P < 0.05) recovered to 8.58-8.75 log CFU/mL in the presence of all Tween treatments. However, recovery of c9, t11 CLA production was only demonstrated in the presence of Tween 80 (72.89 μg/mL). Stepwise increasing oxgall in a concentrations range from 0.1% to 0.9% according to human intestinal physiological environments, Tween 80 still showed significant (P < 0.05) recovery ability on growth (8.91-8.04 log CFU/mL) and c9, t11 CLA (69.22-34.27 μg/mL) production. The effect of Tween 80 on growth and production was also investigated in the presence of different types of bile salts (sodium salts of cholic acid (CA), deoxycholic acid (DCA), chendeoxycholic acid (CDCA), glycocholic acid (GCA) and taurocholic acid (TCA)). Results showed that Tween 80 could significantly (P < 0.05) recover c9, t11 CLA production in the presence of all types of bile salts, but the Tween 80 could only significantly (P < 0.05) recover viable counts of the strain in the presence of CA, DCA and CDCA. This recovery ability could be attributed to the protection of leakage of intracellular material. Additionally, although bile salts inhibited growth and c9, t11 CLA production by the growing cell, it promoted the c9, t11 CLA production by the resting cell.     

荧光假单孢菌高活性木聚糖酶产酶研究

从盐碱土中获得一样荧光假单孢菌（P.flu．01）,研究了该菌木聚糖酶产酶条件。虽然木聚糖为木聚糖酶产酶最佳碳源,但以未处理的玉米芯为碳源,胰蛋白际和酵母混音为氮源时．经60h培养后,木聚糖酶活高达164．OIU／mL,而CMC酶活很低,只有0．29IU/mL。同时该菌对pH值具有广泛的适应性,在起始pH＝6．0－11．0范围内其木聚糖产酶能力相差不大。有机氛胰蛋白股和酵母混音比无机氛更有利于酶活的提高,并且木聚糖酶活力的提高和有机氟含量增加成正比。玉米芯的物理状态即粗细度对产酶影响不大,但玉米芯的含量增加对广酶有强烈的挺进作用。该酶最合适pH值为6．5,最适反应温度为50℃。