细菌产木聚糖酶发酵条件的研究*

研究了碳源、氮源以及其他因子对木聚糖酶高产菌ＷＬＵＮ０２４（Ｐｓｅｕｄｏｍｏｎａｓ ｓｐ．）产酶的影响,结果表明在麸皮６ｇ／Ｌ、（ＮＨ４）２ＳＯ４ ０．８ｇ／Ｌ、Ｋ２ＨＰＯ４ ０．４ｇ／Ｌ、接种量５％－１０％的条件下,３７℃培养３６ｈ,其木聚糖酶活力可达６００ＩＵ／ｍＬ。同时研究了在较优条件下该菌的摇瓶产酶曲线。     

枯草芽孢杆菌中性β—甘露聚糖酶的产生及性质

由土壤中分离出一株产中性β甘露聚糖酶的枯草芽孢杆菌（Ｂａｃｉｌｕｓｓｕｂｔｉｌｉｓ）,编号ＢＭ９６０２。该菌在液体培养条件下,产生中性β甘露聚糖酶。多糖能作为碳源,而单糖不能作为碳源;有机氮源优于无机氮源。产酶最适培养基组成：魔芋粉４％,牛肉蛋白胨和酵母膏各１％。产酶最适培养条件：培养基起始ｐＨ８５,３５℃,振荡培养３６ｈ。以槐豆胶为底物,培养滤液中性β甘露聚糖酶活力为９６ＩＵ／ｍＬ。酶在ｐＨ５０～１００和５０℃下稳定;作用最适条件为ｐＨ６０和５０℃;水解魔芋粉和槐豆胶均产生寡聚糖。     

康宁木霉液体深层发酵生产纤维素酶

以康宁木霉（ Ｔｒｉｃｈｏｄｅｒｍａ　ｋｏｎｉｎｇｉｉ） Ｔ２１５为生产菌,在 ３０ｔ气升式发酵罐中进行了液体深层发酵生产纤维素酶的扩大试验。一、二级罐种子培养基由８％麦麸组成,种龄２４ｈ。产酶培养基由６％稻草粉,１％麦麸和１％蛋白胨组成,起始ｐＨ５．０。每罐装２２ｔ培养基,１０％接种量,通气量０．４ｖｖｍ,罐压０．０８ＭＰａ,２９℃±１℃培养 ９６ｈ。连续试验 ５批,平均发酵液酶活力： ＣＭＣ－Ｎａ活力 ７８．３ＩＵ／ｍＬ,脱脂棉活力 １.３ＩＵ／ｍＬ,水杨苷活力１.４ＩＵ／ｍＬ,滤纸活力     

芽孢杆菌M50产生β—甘露聚糖酶的条件研究

从土壤中分离到９株产生β－甘露聚糖酶的芽孢杆菌（Ｂａｃｉｌｌｕｓ ｓｐ．）。Ｂａｃｉｌｌｕｓ ｓｐ．Ｍ５０２５０ｍＬ三角瓶摇瓶培养试验,以４％的魔芋粉为碳源,１．０％（ＮＨ４）２ＳＯ４为氮源,０．３５％Ｎａ２ＣＯ３,３０～３４℃培养６０ｈ产酶达到高峰。酶活力为１８０～２２０ｕ／ｍＬ。１００Ｌ罐发酵,在３０～３２℃,１：０．７５ｖｖｍ通气量,２００ｒ／ｍｉｎ条件下,发酵液酶活力高达３３０ｕ／ｍＬ。     

链霉菌Z94-2碱性脂肪酶产生条件及酶学性质

在１５２ 株脂肪酶产生菌中,链霉菌Ｚ９４２ 产脂肪酶活力为５９６ｕ／ ｍＬ,其最适培养基（ｇ／Ｌ） 为：糊精１０ 、黄豆饼粉３０ 、尿素１０ 、Ｋ２ＨＰＯ４ ０－５ 、ＭｇＳＯ４ ０－５ 、ＮａＣｌ １ 和ＡＥＯ９ ０ ．５ ,产酶的最适条件为：初始ｐＨ９ ．５ ～１０－０ ,在２６ ℃培养４８ｈ 。用ＰＶＡ 橄榄油乳化系统测定该酶的最适ｐＨ９ ．８ ,最适温度３７ ℃,在ｐＨ８－６ ～１０－２ 于５ ℃存放２４ ｈ ,酶活力不变。０－１４ｍｏｌ／Ｌ 的氯化钙有较大的激活作用。     

曲霉木聚糖酶发酵条件与性质

从实验室培养污染物上分离出一株产木聚糖酶活力高的曲霉（ＡｓｐｅｒｇｉｌｌｕｓＳｐ．）Ａ３菌株。研究了其发酵过程,该菌经３０℃,培养９６小时,酶活力可达３２０ＩＵ／ｍｌ,研究了碳源,氮源,发酵起始ｐＨ值及通风量对产酶的影响。酶的最适反应温度为５５℃,最适ｐＨ值为４．４。在不同温度下保温１小时,测得该酶的半失活温度为５１℃。     

黑曲霉产木聚糖酶发酵条件的研究

正交设计试验结果表明,黑曲霉（Ａｓｐｅｒｇｉｌｌｕｓ ｎｉｇｅｒ ｍ１２）产木聚糖酶活力达７６．６０ｕ／ｍｌ,合适的产酶发酵条件如下,培养基（ｇ／Ｌ）：麸皮４０,尿素６．６７,ＫＨ２ＰＯ４ １．０,ＭｇＳＯ４．７Ｈ２Ｏ０．５,ＮａＣｌ０．３,Ｔｗｅｅｎ－８０ ３．０,ＣａＣＯ３ ２．０,２８℃,１２０ｒ／ｍｉｎ水浴振荡培养５．５ｄ。     

芽孢杆菌M_(50)产生β甘露聚糖酶的条件研究

从土壤中分离到９ 株产生β甘露聚糖酶的芽孢杆菌（ Ｂａｃｉｌｌｕｓ ｓｐ ．） 。Ｂａｃｉｌｌｕｓｓｐ ． Ｍ５０２５０ｍ Ｌ三角瓶摇瓶培养试验,以４ ％ 的魔芋粉为碳源,１－０ ％ （ ＮＨ４）２ＳＯ４ 为氮源,０－３５ ％Ｎａ２ＣＯ３ ,３０ ～３４ ℃培养６０ｈ 产酶达到高峰。酶活力为１８０ ～２００ｕ／ｍ Ｌ。１００Ｌ 罐发酵,在３０ ～３２ ℃,１∶０ ．７５ｖｖｍ 通气量,２００ｒ／ｍｉｎ 条件下,发酵液酶活力高达３３０ｕ／ｍ Ｌ。酶的最适反应温度和ｐＨ 分别为５０ ℃和６－０ ,低于５０ ℃,ｐＨ５ ．０ ～７ ．０ 酶稳定。Ｆｅ^３＋ 、Ａｌ^３＋ 、ＥＤＴＡ、Ｈｇ^２＋ 对酶有抑制作用,而Ｂａ^２＋ 、Ｍｎ^２＋ 对酶有激活作用。发酵粗酶液对苎麻精干麻精练,显示对精干麻的半纤维素残胶具有降解作用。     

树状黄杆菌变株U-616葡萄糖异构酶的研究

以树状黄杆菌（Ｆｌａｖｏｂａｃｔｅｒｉｕｍａｒａｂｏｒｅｓｃｅｎｓ）ＮＲＲＬ１１０２２为出发菌株,用紫外线对其进行诱变,经筛选得到一株葡萄糖异构酶的高产菌株Ｕ－６１６,其酶活力提高３１％。经保存三年和多次传代复测,其产酶能力保持稳定。其生长和产酶需较高的溶氧水平,最适产酶温度为３０℃,最适产酶ｐＨ为７．０－７．５,铁离子对其生长和产酶无明显的影响。所产葡萄糖异构酶的最适温度为６０－８０℃,最适ｐＨ为７．５－８．５,Ｃｏ２＋和Ｍｇ２＋对酶有激活作用,对金属离子耐受性较强,对Ｃａ２＋不敏感,热稳定性较好。树状黄杆菌变株Ｕ－６１６是一株产胞内葡萄糖异构酶的优良菌株。     

链霉菌Z94-2碱性脂肪酶产生条件及酶学性质

在１５２株脂肪酶产生菌中,链霉菌Ｚ９４－２产脂肪酶活力为５９６ｕ／ｍＬ,其最适培养基（ｇ／Ｌ）为：糊精１０、黄豆饼粉３０、尿素１０、Ｋ２ＨＰＯ４０．５、ＭｇＳＯ４０．５、ＮａＣｌ１和ＡＥＯ９０．５,产酶的最适条件为：初始ｐＨ９．５～１０．０,在２６℃培养４８ｈ。用ＰＶＡ橄榄油乳化系统测定该酶的最适ｐＨ９．８,最适温度３７℃,在ｐＨ８．６～１０．２于５℃存放２４ｈ,酶活力不变。０．１４ｍｏｌ／Ｌ的氯     

Thermostable, alkalophilic and cellulase free xylanase production by Thermoactinomyces thalophilus subgroup C

Thermoactinomyces thalophilus produced cellulase free extracellular endo-1,4-beta-xylanase (EC 3.2.1.8) at 50 degrees C and pH 8.5. Maximum xylanase production was achieved in fermentation medium using birchwood xylan as substrate after 96 h of growth at 50 degrees C. Other agricultural substrates such as wheat bran, wheat straw, sugarcane bagasse and cornstover produced less xylanase. The crude enzyme preparation from mutant T. thalophilus P2 grown under optimised fermentation conditions showed no cellulase contamination and maximum xylanase activity of 42 U/ml at 65%deg;C and pH 8.5-9.0. This enzyme with initial xylanase activity of 42 U/ml was found thermostable up to 65 degrees C and retaining 50% of its activity after its incubation for 125 min at 65 degrees C.     

Extracellular xylanase production by Fusarium species in solid state fermentation

Fusarium sp. has been shown to be a promising organism for enhanced production of xylanases. In the present study, xylanase production by 21 Fusarium sp. isolates (8 Fusarium culmorum, 4 Fusarium solani, 6 Fusarium verticillioides and 3 Fusarium equiseti) was evaluated under solid state fermentation (SSF). The fungal isolate Fusarium solani SYRN7 was the best xylanase producer among the tested isolates. The effects of some agriculture wastes (like wheat straw, wheat bran, beet pulp and cotton seed cake) and incubation period on xylanase production by F. solani were optimized. High xylanase production (1465.8 U/g) was observed in wheat bran after 96 h of incubation. Optimum pH and temperature for xylanase activity were found to be 5 and 50 degrees C, respectively.     

Production of alkali tolerant cellulase free xylanase in high levels by Bacillus pumilus SV-205

The fermentation conditions were optimized for hyper production of xylanase from Bacillus pumilus SV-205. The bacterium secretes high levels (7382.7±1200 IU/mL) of cellulase-free xylanase using wheat bran led to 21.63 fold increase in activity. A combination of yeast extract and peptone stimulated highest xylanase production (2448.0 IU/mL) as compared to other combinations. The most important characteristic of the enzyme is its high pH stability (100%) over a broad pH range of 6-11 for 24h. Thermostability studies revealed that enzyme retained 65% activity after an incubation of 2h at 60°C. The level of production is remarkable as compared to earlier reports.     

木聚糖酶生产菌株的筛选及产酶条件的优化

以甘蔗渣半纤维素为碳源,从垃圾场土壤中分离到6株分解半纤维素的菌株。通过固态发酵的木聚糖酶活力比较筛选到1株木聚糖酶活力较高的菌株。该菌株18S rDNA序列与曲霉（Aspergillus sp.）的同源性达97%,根据对菌株形态学分析和18S rDNA序列分析的结果,将该菌株鉴定为曲霉HQ3。HQ3的最佳产酶条件为：甘蔗渣:麸皮为7:3（W/W）,固液比为1:4（W/W）,尿素0.4 %,pH7.0,温度30℃,发酵产酶时间4 d。在最佳产酶条件下,其木聚糖酶活最高可达3421U/g干曲。     

Cost-effective and concurrent production of industrially valuable xylano-pectinolytic enzymes by a bacterial isolate Bacillus pumilus AJK

Simultaneous production of xylanase and pectinase by Bacillus pumilus AJK under submerged fermentation was investigated in this study. Under optimized conditions, it produced 315?±?16 IU/mL acidic xylanase, 290?±?20 IU/mL alkaline xylanase, and 88?±?9 IU/mL pectinase. The production of xylano-pectinolytic enzymes was the highest after inoculating media (containing 2% each of wheat bran and Citrus limetta peel, 0.5% peptone, 10?mM MgSO₄, pH 7.0) with 2% of 21-hr-old culture and incubated at 37°C for 60?hr at 200?rpm. Xylanase retained 100% activity from pH 6.0 to10.0 after 3?hr of incubation, while pectinase showed 100% stability from pH 6.0 to 9.0 even after 6?hr of incubation. Cost-effective and concurrent production of xylanase and pectinase by a bacterial isolate in the same production media suggests its potential for various biotechnological applications. This is the first report of simultaneous production of industrially important extracellular xylano-pectinolytic enzymes by B. pumilus.     

Expression of recombinant Bacillus licheniformis xylanase A in Pichia pastoris and xylooligosaccharides released from xylans by it

The mature peptide of Bacillus licheniformis xylanase A (BlxA) was successfully expressed in Pichia pastoris under the control of AOX1 promoter. After 96-h 0.25% methanol induction, the activity of recombinant B. licheniformis xylanase A (reBlxA) in culture supernatant was 122.9 U/mg. Enzymatic properties assays showed that the optimum temperature and pH for reBlxA were 60 degrees C and pH 6.0, respectively. When treated at 70 degrees C, pH 6.0 for 2 min, the residual activities of the reBlxA were 76%. Over 80% of reBlxA activity was retained after treatment of the enzyme by preincubation over a pH range of 5.0-9.0 for 1h at 25 degrees C. High performance liquid chromatography (HPLC) analysis revealed that xylotriose (X3) was the main hydrolysis product released from birchwood xylan and wheat bran insoluble xylan by reBlxA. The mode of action studies showed that reBlxA was an endo-acting xylanase and xylobiose (X2), xylotriose, xylotetraose (X4), xylopentaose (X5), and xylohexaose (X6) could be hydrolyzed by it. This is the first report on the expression of reBlxA in yeast and on determining and quantifying the hydrolysis products released from xylans by reBlxA.     

Statistical optimization of medium components for the production of xylanase byAspergillus niger KK2 in submerged cultivation

Medium composition was optimized for the production of xylanase byAspergillus niger KK2 using statistical experimental designs. Corn steep liquor (CSL) and industrial yeast extract (IYE) were the most important factors affecting xylanase activity. The medium that produced the optimum conditions for the production of xylanase contained 3% rice straw, 1% wheat bran, 6.3% CSL, 0.15% IYE, and 0.5% KH₂PO₄. After 4 days of cultivation under optimized conditions in a 2.5-L stirred tank reactor the activity and productivity of xylanase were 620 IU/mL and 6,458 IU/L.h, respectively. The highest xylanase activity obtained using the optimized medium was 80% greater than the activity obtained using basal medium. The xylanase activity predicted by a polynomial model was 670 IU/ml.     

Properties and application of a partially purified alkaline xylanase from an alkalophilic fungus Aspergillus nidulans KK-99

An alkalophilic Aspergillus nidulans KK-99 produced an alkaline, thermostable xylanase (40 IU/ml) in a basal medium supplemented with wheat bran (2% w/v) and KNO3 (at 0.15% N) pH 10.0 and 37 degrees C. The partially purified xylanase was optimally active at pH 8.0 and 55 degrees C. The xylanase was stable in a broad pH range of 4.0-9.5 for 1 h at 55 degrees C, retaining more than 80% of its activity. The enzyme exhibited greater binding affinity for xylan from hardwood than from softwood. The xylanase activity was stimulated (+25%) by Na+ and Fe2+ and was strongly inhibited (maximum by 70%) by Tween-20, 40, 60, SDS, acetic anhydride, phenylmethane sulphonyl fluoride, Triton-X-100. The xylanase dose of 1.0 IU/g dry weight pulp gave optimum bleach boosting of Kraft pulp at pH 8.0 and temperature 55 degrees C for 3 h reaction time.     

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.     

Xylanase production by Aspergillus awamori. Development of a medium and optimization of the fermentation parameters for the production of extracellular xylanase and beta-xylosidase while maintaining low protease production

A growth medium was developed for maximal production in batch culture of extracellular xylanase and beta-xylosidase by Aspergillus awamori CMI 142717 and a mutant (AANTG 43) derived from the wild-type strain. The optimum pH for the production of xylanase and beta-xylosidase was 4.0. The best temperature of xylanase production was 30 degrees C; 35 degrees C was optimal for beta-xylosidase. Protease production was never completely suppressed under any of the conditions tested. However, protease titre was 3.5-fold less than the control in medium in which proteose peptone and yeast extract were omitted: the level of xylanase was not affected (8.6 U mL(-1)) but beta-xylosidase titre was increased 4.7-fold to 1.5 U mL(-1). When corn steep liquor was used as the sole nitrogen source, xylanse and beta-xylosidase titres were further increased by 1.5- and 1.9-fold, respectively. Of the carbon sources investigated, ball-milled oat straw or oat spelt xylan produced the highest titres of xylanse and beta-xylosidase. None of the soluble carbon sources investigated produced the high titres of xylanase or beta-xylosidase induced by either oat straw for xylanse and beta-xylosidase was 2% and the optimum spore inoculum was between 10(6) and 10(7) spores/mL(-1) final concentration. The level of xylanse activity obtained in the culture filtrates of the mutant was a remarkable 820 U mL(-1) when the reducing sugar released was measured by the dinitrosalicylic acid method. This enzyme titre would appear to be the highest reported so far. The xylanases system contained the correct balance of enzymes to effect extensive hydrolysis of oat spelt xylan. The protease titre was very low.