Alkalitalea saponilacus产木聚糖酶的碳源优化及酶学特性

【目的】确定厌氧盐碱细菌Alkalitalea saponilacus产木聚糖酶所需的碳源,优化木聚糖粗酶的提取条件并分析酶学性质。【方法】应用GC技术分析A.saponilacus发酵木聚糖的主要产物;利用二硝基水杨酸法(DNS)测定木聚糖酶活力以获得最优的碳源、提取粗酶的最佳条件及其酶学特性。【结果】A.saponilacus以不同来源木聚糖为底物时,发酵产生的主要产物丙酸含量都在80%以上。若以0.4%(W/V)蔗糖+0.1%(W/V)桦木木聚糖为复合碳源时,木聚糖酶活力是以桦木木聚糖或者蔗糖为单一碳源时的3.2倍。木聚糖酶的酶活力在盐度2%–6%、pH 7.0和55°C达到最佳且在该条件下的酶活力为590 IU/mg。此外,该酶活力在0.2%Tween 20存在时增加,而在5 mmol/L Mg~(2+)和0.2%Triton X-100存在时无显著影响,但在Cu~(2+)、Fe3+和Ni~(2+)等金属离子存在时则被显著抑制。【结论】A.saponilacus发酵主产物丙酸以及生物合成的木聚糖酶在工业生产中具有广泛的应用前景。     

厌氧菌群SVY42产酶条件分析及产木聚糖酶菌株的分离鉴定

以美国内华达州大盆地温泉采集样品为材料,富集获得纤维素及半纤维素高效稳定降解厌氧菌群SVY42,以巨菌草、甘蔗渣、废菇筒、羧甲基纤维素钠、滤纸、木聚糖为碳源,分析菌群SVY42产内切葡聚糖酶(CMC酶)、β-葡萄糖苷酶和木聚糖酶的情况。在此基础上,以木聚糖为底物筛选高产木聚糖酶的菌株。菌群SVY42在以巨菌草作为碳源时的β-葡萄糖苷酶活最高为0.23 U/mL,以木聚糖作为碳源时CMC酶活和木聚糖酶活均为最高,分别为0.31 U/mL和0.35 U/mL。从菌群SVY42中筛选得到1株高产木聚糖酶厌氧菌株SVY42-1,该菌在最适温度41℃和pH 8.0条件下,其木聚糖酶活力为0.26 U/mL,对其进行16S rDNA序列系统进化分析,SVY42-1与已知菌株的最高同源性仅为93.81%,初步鉴定属于新属。     

里氏木霉GXC木聚糖酶的研究

研究了里氏木霉GXC产木聚糖酶的条件和酶学性质。结果表明,适宜产酶碳源为乳糖、甘露糖、棉子糖、木聚糖和麸皮,氮源为牛肉膏和酵母膏;产酶的最适初始pH为4．0,30℃培养60h。对以麸皮为碳源的培养液进行纯化的酶特性研究表明,木聚糖酶的最适反应温度为50℃,pH为5．5,该酶在pH5．0－7．0和40℃以下相对稳定。Fe^2 和Mn^2 对木聚糖酶有较大的促进作用,Cu^2 、Fe^2 具有抑制作用。     

木聚糖酶菌株的筛选及酶切位点的分析

以甘蔗残渣木聚糖为原料,通过唯一碳源选择性培养基筛选水解木聚糖的菌株,并对该菌株酶解木聚糖的条件进行了优化和酶切位点的推测。结果表明,温度60℃、时间30min、pH6.0时为最佳酶促反应条件,在该条件下菌株不能完全降解木聚糖,说明该菌株含有对木聚糖酶解的单酶,其酶活达到6.494U/mL;根据对直链淀粉的酶切分析,酶切位点是以16～18个葡萄糖为最小单位进行的,这种低聚糖的产生可能为今后的木聚糖或淀粉的应用开拓新领域。     

嗜热真菌耐热木聚糖酶的产酶条件和酶谱分析*

嗜热真菌Thermomyces lanuginosus CBS288.54-M18耐热木聚糖酶的产酶条件和酶谱分析结果表明：玉米芯水不溶木聚糖相对于其它来源木聚糖为最佳碳源,而酵母提取物和蛋白胨作为复合氮源时效果最好。培养基最适初始pH值为7．0,最适培养温度为50℃。在最适条件下发酵所产木聚糖酶活力最高达1.834u／mL。另外,SDS-PAGE和酶谱分析(变性和非变性状态下)结果都表明该菌只产生一种分子量约为26kD的G/11族木聚糖酶。     

耐碱性木聚糖酶产酶菌株的选育

目的:筛选出产碱性木聚糖酶酶活力高的菌株。方法:从碱性环境中采集样品,以自制木聚糖为惟一利碳源,采用刚果红透明圈法于摇瓶发酵法相结合筛选出18株产木聚糖酶酶活较高的菌株,其中1株酶活最高可达335.14 IU/ml。结果:通过培养特性及形态特征初步鉴定为芽孢杆菌。对部分酶学性质研究的结果表明:其作用最适温度60℃,最适pH8.0,在pH9.0条件下仍具有80%酶活力。结论:属于耐碱性木聚糖酶,具有很好的工业应用前景。     

产木聚糖酶的沿海红树林真菌筛选及其培养与酶活测定条件优化

从香港海岸红树林分离到的 77株真菌中有 34株可产生木聚糖酶 ,从中选出CY2 80 9(Staganosporasp .)、CY4 786和CY5 0 4 0等 3菌株与已知陆生产酶菌株HU5 0 4 8(Aspergillusawamori)进行产木聚糖酶的比较研究。根据培养液中菌丝生物量、木聚糖酶活力和木糖等价还原糖含量等指标的测定 ,菌株CY4 786在起始pH 7 8的木聚糖 酵母膏 海盐液体培养基中 2 5℃下震荡 (10 0r min)培养 7d产酶最佳 ;粗酶液在 5 0℃和pH 4 6的优化条件下进行测定 ,木聚糖酶活力达到 1 0 7× 10 4 U mL。结果表明 ,红树林真菌起着半纤维素降解者的作用 ,沿海红树林环境中存在着可资利用的木聚糖酶产生菌。作者讨论了利用发酵液中木糖等价还原糖含量的动态变化作为快速筛选产木聚糖酶菌株的指标的可能性     

牦牛源木聚糖酶产生菌的筛选和鉴定

目的以牦牛粪便为样本,筛选并鉴定产木聚糖酶菌株。方法利用碱提取法从玉米芯中提取木聚糖,以自制木聚糖为唯一碳源,从牦牛牛粪中筛选产木聚糖酶细菌,利用16S rDNA基因序列分析鉴定菌种,3,5-二硝基水杨酸法(DNS)测定其产酶能力并分析所产酶的酶学特性。结果筛选获得牦牛源产木聚糖酶类芽胞杆菌,所产木聚糖酶的最适反应条件为50℃、pH 8.0,在pH值为7.0或8.0以及温度50℃条件下,表现出较好的稳定性,Mn~(2+)对酶活力具有显著抑制作用,该菌最佳发酵时间为12 h,酶活最高达到1.2 U/mL。结论该菌所产木聚糖酶能够针对性地降解玉米芯木聚糖,在畜牧业和工业上有一定的应用价值。     

碱性木聚糖酶产酶菌株—芽胞杆菌M-26的选育

从造纸厂的废水中采集样品,以木聚糖为唯一碳源初筛菌株,然后用刚果红透明圈平板选育,最后通过摇瓶发酵选育出碱性木聚糖酶高产菌株M-26,基础产酶活力达330 IU/mL;通过菌种形态学、培养特征和16S rDNA鉴定为短小芽胞杆菌;酶学性质研究表明:最适作用温度和pH分别为55℃和8.0,且具有一定的耐碱性;通过发酵条件研究,M-26最高产酶活力可达625 IU/mL。     

具有高木二糖形成活力的木聚糖酶生产菌株的筛选与产酶培养基的优化

从土样中筛选出一株产木聚糖酶的青霉,该青霉所产木降糖酶具有很高的木二糖形成活力,经鉴定为顶青霉,其木聚糖酶的合成与分泌受木聚糖等木糖苷类物质的诱导,麸皮对其木聚糖酶的合成也有促进作用,优化产酶液体培养主要成分的配比为：麸皮：玉米芯木聚糖：玉米芯粉;蛋白胨（或尿素）＝1：1：1：0．6（0．4）,摇瓶96h达到最大酶活,最高木聚糖酶活达到289．3U／ml,该菌所产木聚糖酶的最适作用条件为45－50度,PH4．4,在PH4．4－8．0范围内稳定。     

Xylanolytic Activity of Clostridium acetobutylicum

Of 20 strains of Clostridium spp. screened, 17 hydrolyzed larch wood xylan. Two strains of Clostridium acetobutylicum, NRRL B527 and ATCC 824, hydrolyzed xylan but failed to grow on solid media with larch xylan as the sole carbon source; however, strain ATCC 824 was subsequently found to grow on xylan under specified conditions in a chemostat. These two strains possessed cellulolytic activity and were therefore selected for further studies. In cellobiose-limited continuous cultures, strain NRRL B527 produced maximum xylanase activity at pH 5.2. Strain ATCC 824 produced higher xylanase, xylopyranosidase, and arabinofuranosidase activities in chemostat culture with xylose than with any other soluble carbon source as the limiting nutrient. The activities of these enzymes were markedly reduced when the cells were grown in the presence of excess glucose. The xylanase showed maximum activity at pH 5.8 to 6.0 and 65°C. The enzyme was stable on the alkaline side of pH 5.2 but was unstable below this pH value. The extracellular xylanolytic activity from strain ATCC 824 hydrolyzed 12% of the larch wood xylan during a 24-h incubation period, yielding xylose, xylobiose, and xylotriose as the major hydrolysis products. Strain ATCC 824, after being induced to grow in batch culture in xylan medium supplemented with a low concentration of xylose, failed to grow reproducibly in unsupplemented xylan medium. A mutant obtained by mutagenesis with ethyl methanesulfonate was able to grow reproducibly in batch culture on xylan. Both the parent strain and the mutant were able to grow with xylan as the sole source of carbohydrate in continuous culture with the pH maintained at either 5.2 or 6.0. Under these conditions, the cells utilized approximately 50% of the xylan.     

Purification and properties of a xylanase from Streptomyces lividans.

An extracellular xylanase produced by a cellulase-negative mutant strain of Streptomyces lividans 1326 was purified to homogeneity. The purified enzyme has an apparent Mr of 43,000 and pI of 5.2. The pH and temperature optima for the activity were 6.0 and 60 degrees C respectively, and the Km and Vmax. values, determined with a soluble oat spelts xylan, were 0.78 mg/ml and 0.85 mmol/min per mg of enzyme. The xylanase showed no activity towards CM-cellulose and p-nitrophenyl beta-D-xyloside. The enzyme degraded xylan, producing mainly xylobiose, a mixture of xylo-oligosaccharides and a small amount of xylose as end products. Its pattern of action on beta-1,4-D-xylan indicates that it is a beta-1,4-endoxylanase (EC 3.2.1.8).     

Purification and characterization of two xylanases from Trichoderma longibrachiatum.

Two endoxylanases were purified from the culture medium of Trichoderma longibrachiatum. Both enzymes were highly basic, and lacked activity on carboxymethyl-cellulose. An enzyme of 21.5 kDa (xylanase A) had a specific activity of 510 U/mg protein, a Km of 0.15 mg soluble xylan/ml, possessed transglycosidase activity and generated xylobiose and xylotriose as the major endproducts from xylan or xylose oligomers. A larger enzyme of 33 kDa (xylanase B) had a specific activity of 131 U/mg protein, a Km of 0.19 mg soluble xylan/ml, lacked detectable transglycosidase activity and generated xylobiose and xylose as major endproducts from xylan and xylose oligomers. Xylotriose was the smallest oligomer attacked by both enzymes. In addition, xylotriose inhibited hydrolysis of xylopentanose by both enzymes, while xylobiose appeared to inhibit xylanase B, but not xylanase A.     

Cloning of a Bacillus sp. BP-23 gene encoding a xylanase with high activity against aryl xylosides

Abstract The xynB gene encoding a xylanase from the recently isolated Bacillus sp. strain BP-23 has been cloned and expressed in Escherichia coli . The enzyme produced in this host shows a molecular size of 41 kDa and a pI of 4.5. The pH and temperature at which the highest activity was found were 5.5 and 50°C respectively. Crude xylanase B showed activity on xylan, aryl xylosides, xylotetraose and xylotriose, while xylobiose was not hydrolyzed by the enzyme. Xylanase B showed high specific activity on aryl xylosides, probably as a result of the transxylosidase activity detected.     

细菌木聚糖酶高产菌的选育及产酶条件

木聚糖是一种在植物体内大量存在的半纤维素,是在自然界中含量仅次于纤维素的一种可再生植物纤维。木聚糖酶(ｘｙｌａｎａｓｅ,ＥＣ3.2.1.8)是一类能够特异降解木聚糖的酶类。近年来,人们将其广泛用于造纸工业的纸浆生物处理,与其他消化酶类一起用作饲料添加剂,以及应用于食品加工工业和纺织工业等。木聚糖酶可以由许多种微生物产生[1],我国多集中于霉菌木聚糖酶的研究。本文报告了一株细菌木聚糖酶产生菌的筛选及产酶条件的研究结果。1　材料和方法11　菌株本实验室分离、保存的木聚糖酶产生菌ＷＸＵＬＩ11及其突变株ＷＬＵＮ024。12　培养…     

Thermal stability of beta-xylanases produced by different Thermomyces lanuginosus strains

The thermostability of beta-xylanases produced by nine thermophilic Thermomyces lanuginosus strains in a coarse corn cob medium was assessed. The xylanase produced by T. lanuginosus strain SSBP retained 100% of its activity after 6 h at temperatures up to 65 degrees C. In comparison seven ATCC strains and the DSM 5826 strain of T. lanuginosus only retained 100% xylanase activity at temperatures up to 60 degrees C. Culture filtrates of T. lanuginosus strain SSBP grown on coarse corn cobs, oatspelts xylan, birchwood xylan, wheatbran, locust beangum, and sugar cane bagasse, retained 100% xylanase activity at temperatures up to 60 degrees C. The xylanase produced on corn cobs was the most thermostable and showed an increase of approximately 6% from 70 degrees C to 80 degrees C. The T(1/2) of all strains at 70 degrees C at pH 6.5 varied greatly from 63 min for strain ATCC 28083 to 340 min for strain SSBP. The xylanase of strain SSBP was much less thermostable at pH 5.0 and pH 12.0 with T(1/2) values of 11.5 min and 15 min, respectively at 70 degrees C. At 50 degrees C, the enzyme of T. lanuginosus strain SSBP produced on coarse corn cobs was stable within the pH range of 5.5-10.0. Furthermore, the enzyme retained total activity at 60 degrees C for over 14 days and at 65 degrees C for over 48 h. The xylanase of T. lanuginosus strain SSBP possesses thermo- and pH stability properties that may be attractive to industrial application.     

Optimization of cellulase-free xylanase production by a novel yeast strain

Summary A novel yeast strain, NCIM 3574, isolated from a decaying wood produced up to 570 IU ml^–1 of xylanolytic enzymes when grown on medium containing 4% xylan. The yeast strain also produced xylanase activity (40–50 IU ml^–1) in the presence of soluble carbon sources like xylose or arabinose. No xylanase activity was detected when the organism was grown on glucose. The crude xylanase preparation showed no activity towards cellulolytic substrates but low levels of -xylosidase (0.1 IU ml^–1) and -l-arabinofuranosidase (0.05 IU ml^–1) were detected. The temperature and pH optima for the crude xylanase preparation were 55°C and 4.5 respectively. The crude xylanase produced mainly xylose from xylan within 5 min. Prolonged hydrolysis of xylan produced xylobiose and arabinose, in addition to xylose, as the end products. The presence of arabinose as one of the end products in xylan hydrolysate could be due to the low levels of arabinofuranosidase enzyme present in the crude fermentation broth.     

里氏木霉GXC木聚糖酶的研究

研究了里氏木霉GXC产木聚糖酶的条件和酶学性质。结果表明,适宜产酶碳源为乳糖、甘露糖、棉子糖、木聚糖和麸皮,氮源为牛肉膏和酵母膏;产酶的最适初始pH为4.0,30℃培养60h。对以麸皮为碳源的培养液进行纯化的酶特性研究表明,木聚糖酶的最适反应温度为50℃,pH为5.5,该酶在pH5.0(7.0和40℃以下相对稳定。Fe3+和Mn2+对木聚糖酶有较大的促进作用,Cu～2+、Fe～2+和Ca～2+ 具有抑制作用。