斜卧青霉纤维素酶和木聚糖酶高产菌株的选育

以纤维素酶高产菌株斜卧青霉A50为出发菌株,通过紫外诱变原生质体获得1株木聚糖酶活力提高80%而纤维素酶活力没有改变的6号菌。蛋白质电泳和酶谱检测结果显示,纤维素酶谱基本无差别,而木聚糖酶谱显示6号菌比A50多了一条带。6号菌优化后的产酶培养基组成为:麸皮7%、葡萄糖0.1%,该条件下,纤维素酶活为19.7IU/mL,木聚糖酶活力为215.4IU/mL。     

米曲霉木聚糖酶生产菌的理性选育及发酵优化

目的：米曲霉木聚糖酶生产菌的理性选育及发酵优化。方法：以米曲霉FS018为出发菌株,采用紫外和激光诱变先后处理3代,以抗高浓度葡萄糖阻遏效应为筛选模型获得一株高产木聚糖酶菌株FST036,并对该菌株的发酵培养基进行了初步优化。结果：突变株FST036产酶水平可达4200．57U／mL,产酶水平比出发菌株提高了24％。对该菌株的发酵培养基初步优化结果表明：培养基的最适氮源为牛肉膏;最适碳源为麸皮与玉米芯组合,总浓度为4％。二者最适比例为7：3;对该菌株的发酵条件初步优化结果表明：最适接种量1％,初始pH6．78,250mL三角瓶装液量为45mL,培养72h酶活可达5404．24U／mL。结论：反复多次诱变处理,并结合抗高浓度葡萄糖阻遏效应作为一种理性筛选模型,为通过诱变育种来获得曲霉木聚糖酶高产菌株提供了一条有效的途径。     

黑曲霉高产β-葡萄糖苷酶菌株的诱变、筛选及发酵条件优化

以黑曲霉TJ02为出发菌,对其孢子进行硫酸二乙酯化学诱变,筛选得到遗传稳定的β-葡萄糖苷酶高产菌株DES-7。诱变株DES-7产酶能力可达28 IU/mL以上,较出发菌株提高30%。同时,对该菌株的发酵培养基进行优化,以玉米芯为碳源,酵母粉和硫酸铵为氮源,其产酶能力达到39 IU/mL,较优化前提高了39.3%。此外,对该菌株的β-葡萄糖苷酶的最适温度和pH以及温度稳定性和pH稳定性进行了测定。     

毛壳霉CQ31的鉴定及固体发酵产木聚糖酶条件的优化

从土壤中筛选出一株产木聚糖酶的真菌CQ31, 经鉴定后命名为毛壳霉CQ31。该菌能够利用几种农业废弃物固体发酵高产木聚糖酶, 玉米杆为最佳碳源。单因素优化试验表明: 以玉米杆为碳源, 胰蛋白胨为氮源, 初始水分含量80%, 初始pH值9.0为最佳产酶条件。在优化后的条件下培养7 d产木聚糖酶水平高达4897 U/g干基碳源, 此时甘露聚糖酶酶活达803 U/g干基碳源。因此, 毛壳霉CQ31固体发酵产木聚糖酶和甘露聚糖酶具有一定的工业化应用前景。     

紫外诱变选育木聚糖酶高产菌株及产酶条件初步研究

以短小芽孢杆菌(Bacillus pumilus)HJ-04为出发菌株,通过紫外诱变的方法筛选得到一株木聚糖酶高产菌株B6,其酶活提高约30%.通过因素轮换试验和L9(34)正交试验结果得出B-6菌株产酶的最佳营养条件及发酵条件.结论:4%啤酒糟、2%玉米芯、2%牛肉膏、0.15%FeSO4、1.5%Na2HPO4,pH 8～9,35℃,170r/min培养60h,产酶活力达到536.72IU/mL.     

5′—磷酸二酯酶高产菌株的选育和发酵培养条件的优点

以ATCC14994为出发菌株,采用紫外线与亚硝基胍相结合的多次诱变育种,获得1株5′-磷酸二酯酶高产菌株HAT2228.通过单因子和正交试验对该菌株的产酶发酵条件进行了优化,优化发酵产酶条件为蔗糖5%,酵母膏0 3%,蛋白胨0.3%,K2HPO4 0.8%,KH2PO40.8%,MgSO4 0.2%,ZnSO4 0.2%,培养基起始pH6 0,接种量10%,培养温度30℃,摇床转速120r/min,发酵时间48h.在优化条件下,HAT2228的产酶水平达1 329u/ml.     

5′-磷酸二酯酶高产菌株的选育和发酵培养条件的优化

以ATCC14994为出发菌株,采用紫外线与亚硝基胍相结合的多次诱变育种,获得1株5′-磷酸二酯酶高产菌株HAT2228.通过单因子和正交试验对该菌株的产酶发酵条件进行了优化,优化发酵产酶条件为:蔗糖5%,酵母膏0 3%,蛋白胨0.3%,K2HPO4 0.8%,KH2PO40.8%,MgSO4 0.2%,ZnSO4 0.2%,培养基起始pH6 0,接种量10%,培养温度30℃,摇床转速120r/min,发酵时间48h.在优化条件下,HAT2228的产酶水平达1 329u/ml.     

木聚糖酶高产菌株的鉴定及产酶条件的优化

目的:通过了解木聚糖酶高产菌株A79的遗传背景.并优化其产木聚糖酶的液体发酵条件,为下一步工业化生产和木聚糖酶制剂的研制奠定基础.方法:通过形态观察和18S rDNA基因的分子系统进化分析,对菌株A79进行鉴定;通过单因素和均匀设计试验,优化其产胞外木聚糖酶的液体发酵条件.结果:通过对18S rDNA基因的分子系统进化分析,菌株A79被鉴定为黑曲霉(Asperillus niger A79).其最佳产酶培养基为:玉米芯5.0%,麸皮0.5%.纤维物质1.O%,玉米浆1.1%.(NH4)2SO40.8%,蛋白胨0.8%,CaCO3 0.5%,KH2PO4 0.23%,MgSO4,·7H2O 0.08%,微量元素(MaIldels)0.08%,pH自然.最佳发酵条件为:接种量5%(2.0×107),28℃、250r/min振荡培养96h.结论:经优化培养,酶活力由前期的50 000u/ml提高到90000u/ml,增加了近50%.     

低能离子注入技术诱变选育木聚糖酶高产菌

利用离子束注入技术对木聚糖酶产生菌黑曲霉(Aspergillus niger)A3进行诱变筛选,得到高产菌株N212。通过正交设计实验,优化了该高产菌的液体发酵条件,发现适合产酶的培养基是:8%玉米芯,1.0%麸皮,0.1%吐温80,0.5%(NH4)2SO4,0.5%NaNO3,其他无机盐的成分与M ande ls营养盐液中的成分一样,pH5.4。在优化后的培养条件下N212的产酶达到600 IU/mL。     

木聚糖酶高产菌株选育

以黑曲霉为出发菌,经紫外线和亚硝基胍（NTG）交替诱变处理,获得一株木聚糖酶高产菌,并初步研究了其固体发酵条件,在该条件下最高酶活力可达3181IU／min.gdw。     

短小芽胞杆菌产碱性木聚糖酶发酵条件的研究

碱性木聚糖酶在碱性条件下催化水解木聚糖,广泛应用于造纸、纺织等领域.着重对短小芽胞杆菌M-11产碱性木聚糖酶的发酵条件进行初步的探索.研究了菌株的生长曲线、确定最佳接种龄为16 h、最佳接种量为1％;确定最适碳源浓度为7％、最适单一氮源为氯化铵、其浓度为1.0％、最适无机盐为氯化铁、其浓度为3 mmol/L;在此基础之上进行6因素3水平的正交试验,确定最适产酶培养基组成:麸皮5％,接种量3％,氯化铵1.2％,氯化铁3.5 mmol/L,硫酸镁0.03％,氯化钠5 mmol/L,磷酸氢二钾0.4％;最适培养条件:接种龄16 h,初始pH 8.0,温度37℃,300 mL摇瓶装液量50 mL,摇床转速220 r/min,发酵周期48 h.通过对发酵条件的优化使发酵液酶活达613 IU/mL.无机氮源为其最适氮源,因此短小芽胞杆菌M-11在碱性木聚糖酶的产品开发上优于短小芽胞杆菌M -26.     

一株产木聚糖酶链霉菌的鉴定及发酵产酶*

以木聚糖为唯一碳源,筛选出一株高产木聚糖酶生产菌株。该菌株经形态特征、 培养特征、生理生化和细胞壁组分分析等实验,鉴定为卷须链霉菌（Streptomyces cirratus).摇瓶发酵产酶实验表明：培养基最佳初始pH值为6．0;玉米芯水不溶木聚糖和蛋白胨分别是最佳的碳源和氮源;添加0．5％吐温80使得木聚糖酶活力提高到原来的2．5倍,发酵液最高酶活达到623u／mL。     

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。     

固态混合发酵提高木聚糖酶和纤维素酶活力的研究

研究了接种比例、接种时间、碳源、氮源等因素对木霉和黑曲霉混合发酵产木聚糖酶和纤维素酶的影响。试验结果表明,当木霉和黑曲霉按4:6同时接种,以玉米芯3．75g、麸皮3．75g、葡萄糖37．5mg为混合碳源,Mandels营养盐11．5mL、添加NH_4NO_37．5mg为氮源,在84h产纤维素酶活力达到230IU/g干物质,木聚糖酶活力达到1308IU/g干物质,与两菌纯培养相比,纤维素酶活力提高163％,木聚糖酶活力提高79．5％。     

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。     

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。     

Production and purification of high levels of cellulase-free bacterial xylanase by Bacillus sp. SV-34S using agro-residue

Xylanase produced from the isolated bacterial strain Bacillus sp. SV-34S showed a 8.74-fold increase in enzyme activity under optimized submerged fermentation conditions. Cultivation using wheat bran as the carbon source and beef extract and (NH₄)H₂PO₄ as the nitrogen source resulted in productivity of 3,454.01 IU/mL xylanase. Xylanase was purified by 12.94-fold, with a recovery of 13.4 % and a specific activity of 3417.2 IU/mg protein, employing ammonium sulphate fractionation followed by cation-exchange chromatography using CM-Sephadex C-50 column chromatography, with a product of 27 kDa. The purified xylanase showed an optimum temperature and pH of 50 °C and 6.5, respectively although it was active even at pH 11.0. The thermostability study revealed that Bacillus sp. SV-34S was thermotolerant, being stable up to 50 °C; the residual activity at 55 and 60 °C was 96 and 93 %, respectively. The enzyme was stable between pH 6.0 and 8.0, although it retained >100 % activity at pH 8.0 and 9.0, respectively, following pre-incubation for 24 h. Xylanase activity was inhibited by various metal ions added to the assay mixture, with maximum inhibition observed in the presence of HgCl₂. The K_m and V_max values of the purified xylanase using birch wood xylan as substrate were 3.7 mg/mL and 133.33 IU/mL, respectively. The isolated bacterial strain produced high levels of extremophilic cellulase-free xylanase. The fact that it can be used in crude form and that it can be produced cheaply with renewable carbon sources make the process economically feasible. The characteristics of the purified enzyme suggest its potential application in industries such as the paper and pulp industry.     

Production and biochemical characterization of a novel cellulase-poor alkali-thermo-tolerant xylanase from <Emphasis Type="Italic">Coprinellus disseminatus</Emphasis> SW-1 NTCC 1165

Fungi producing xylanases are plentiful but alkali-thermo-tolerant fungi producing cellulase-poor xylanase are rare. Out of 12 fungal strains isolated from various sources, Coprinellus disseminatus SW-1 NTCC 1165 yielded the highest xylanase activity (362.1 IU/ml) with minimal cellulase contamination (0.64 IU/ml). The solid state fermentation was more effective yielding 88.59% higher xylanase activity than that of submerged fermentation. An incubation period of 7 days at 37°C and pH 6.4 accelerated the xylanase production up to the maximum level. Among various inexpensive agro-residues used as carbon source, wheat bran induced the maximum xylanase titres (469.45 IU/ml) while soya bean meal was the best nitrogen source (478.5 IU/ml). A solid substrate to moisture content ratio of 1:3 was suitable for xylanase production while xylanase titre was repressed with the addition of glucose and lactose. The xylanase and laccase activities under optimized conditions were 499.60 and 25.5 IU/ml, respectively along with negligible cellulase contamination (0.86 IU/ml). Biochemical characterization revealed that optimal xylanase activity was observed at pH 6.4 and temperature 55°C and xylanase is active up to pH 9 (40.33 IU/ml) and temperature 85°C (48.81 IU/ml). SDS–PAGE and zymogram analysis indicated that molecular weight of alkali-thermo-tolerant xylanase produced by C. disseminatus SW-1 NTCC 1165 was 43 kDa.     

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…