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壳聚糖接枝双醛淀粉固定化黑曲霉木聚糖酶的研究
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摘要
不同的酶由于其结构和特性都不相同,因此选择的载体和固定化方法也各有不同。为了所研究的酶能够很好的适应所选的的固定化载体和采用的固定化方法,载体的选择仍然是固定化酶首要解决的问题。对于木聚糖酶来说,由于底物的一些限制,固定化方法上多采用吸附和载体结合法。本文在此基础上选取了两种无机插层材料水滑石和磷酸锆以及天然材料壳聚糖通过接枝双醛淀粉这些载体,筛选出对黑曲霉A-25来源的木聚糖酶固定化效果较好的载体,并对其固定化工艺进行了优化,进一步研究了固定化酶的酶学特性。研究结果如下:
     1.寻找合适的载体是固定化研究的重要课题之一。通过对所选的几种载体的固定化试验,筛选出了固定化木聚糖酶效果较好的壳聚糖接枝双醛淀粉。然后对壳聚糖接枝双醛淀粉材料固定化木聚糖酶的条件进行了优化,结果表明:3.0g壳聚糖球添加氧化度为95%的双醛淀粉1.0g在70℃条件下处理16h,然后在此条件下,1.0g的载体在添加0.2mo/l pH5.6醋酸缓冲液、温度30℃,加酶量为4ml的条件下进行8h固定化处理效果好,获得的固定化酶回收率可达63%。
     2.与游离酶相比,壳聚糖固定化酶和壳聚糖接枝双醛淀粉固定化酶,其最适pH没有变化,均在4.6,pH的稳定性变化不大,在pH4.6-8.6之间固定化酶稳定性很好,总体壳聚糖接枝双醛淀粉固定化酶的pH稳定性好于壳聚糖直接吸附固定化酶。酶的最适温度提高了,壳聚糖接枝双醛淀粉固定化酶和壳聚糖固定化酶的最适温度分别由游离酶的50℃提高到55℃和60℃,温度稳定性都明显增加了,壳聚糖接枝双醛淀粉以及壳聚糖固定化酶在50℃下半衰期分别是游离酶的2.35倍和1.51倍。同时固定化酶在4℃冰箱内的贮存稳定性比游离酶要好,贮存76天后固定化酶残余活力还保持在85%,游离酶仅为60%。供试的所有离子对壳聚糖固定化酶和壳聚糖接枝双醛淀粉固定化酶的影响有些区别,K~+、Mg~(2+)和EDTA,对壳聚糖固定化酶的影响是部分失活的,但是对壳聚糖接枝双醛淀粉固定化酶是稍微激活的;除Ag~+以外,其它离子对固定化酶都没有激活作用。壳聚糖和壳聚糖接枝双醛淀粉固定化酶对桦木木聚糖的K_m值分别由原酶的1.14mg/ml稍微增加到1.17mg/ml和1.39mg/ml,表明采用壳聚糖或者是壳聚糖接枝双醛淀粉作为固定化材料基本保持了原有酶和底物的亲和性,但是采用壳聚糖接枝双醛淀粉固定化后V_(max)稍有增大。
     3.采用壳聚糖接枝双醛淀粉载体固定化木聚糖酶水解木聚糖得到的水解液成分通过高效液相色谱分析发现,获得了以木二糖和木三糖为主的低聚木糖。
The enzyme because the different of its structure and the characteristic are not all same,therefore the immobilized carrier and the fixed method also respectively have the difference.It is important to look for good characteristic carrier and the best immobilized method,thesedays,people still commit themselves to develop new type carriers and the new pattern.As for the xylanase enzyme,as a result of substrate some limits,the enzyme usually immobilized by the adsorption or covalent. The paper selected the best carrier from two layer inorganic materials(layered Double Hydroxide andα-Zirconium phosphate)and natural polymer- Chitosan,The conditions for immobilization were optimized.The immobilized enzymes were further characterized in terms of their catalytic activity,kinetic parameters and thermal stability, etc.The main results were as follow:
     1.Developing an ideal carrier is one of the important topics of immobilization study. Chitosan grafting Dialdehydle the Starch which was selected from three kinds of different materials showed good immobilization effect on the xylanase from Aspergillus niger-25.The optimal condition for xylanase immobilization were as follow: Dialdehydle the Starch(the oxidized degree is 90%),1.0g;the time pretreated Chitosan at 70℃,16h;the amount xylanase used,4ml(0.2M,pH5.6 acetic- sodium acetic buffer);the temperature and time for immobilization,30℃and 8h,respectively. The activity yield was 63%.
     2.Compared to the free enzyme,Immobilization of xylanase from Aspergillus niger-25 on Chitosan grafting Dialdehydle the Starch and Chitosan showed that:both of the optimum pH were 4.6,pH stability did not change significantly by the immobilization, and was stable at pH 4.6~8.6,however,the immobilization effect by Chitosan grafting Dialdehydle the Starch was better than the Chitosan.The optimum temperature of the immobilized enzyme by Chitosan grafting Dialdehydle the Starch and Chitosan increased from 50℃to 55℃and 60℃,respectively,the thermalstability of the immobilized enzyme increased significantly and for Chitosan grafting Dialdehydle and Chitosan immobilized enzyme at 50℃which their half life were 2.35 and 1.51 times compared to the free enzyme,respectively.The storage stability in 4℃refrigerator was improved after immobilization.,the relativity activity was retained at 85%while the free enzyme was 60%after storaged 76 days.To the both immoblized enzymes,the affect of all ions used in the experiments were different,the metal irons K、Mg and EDTA had activation the immobilized enzyme by the Chitosan grafting Dialdehydle the Starch,but to the Chitosan immobilized enzyme which were inhibited.The other irons could not enhance the activity of the xylanase except Ag iron.For Chitosan grafting Dialdehydle the Starch and Chitosan immobilized enzyme,the K_m values for birch xylan slightly increased from 1.14 mg/ml to 1.39 and 1.17 mg/ml,respectively,which was indicated immobilization of xylanase essentially conserved the affinity of the enzyme towards its substrate.Increases in V_(max)upon immobilization are generally not observed.However,V_(max)values of the immobilized enzyme by Chitosan grafting Dialdehydle the Starch was slightly enhanced in this study.
     3.Immobilized xylanase by the Chitosan grafting Dialdehydle the starch carrier hydrolyzed the Birchwood xylan,the component of the hydrolyzed solution by the HPLC analysed indicated a good result.
引文
[1]Sunna A,Antranikian G.Xylanolytic enzymes from fungi and bacteria.Critical Rev Biotechnol,1997,17(1):39-67
    [2]Joseleau JP,Comtat J,Ruel K.Chemistry sturcture of xylans and their interaction in the plant cell wall.In:Visser J,Beldman G,Kustersvan Someren et al(eds),Xylans and Xylanase.Amsterdam:Elsevier,1992.1-15
    [3]Puls J,Schuseil J.Chemistry of hemicelluloses:relationship between hemicellulose structure and enzymes required for hydrolysis.In:Coughlan MP,Hazlewood GP(eds).Hemicellulose and Hemicellulases.London:Porland Press,1993.1-27
    [4]Chanda SK,Hirst EL,Jones JKN,Percival EGVThe constitution of xylan from esparto grass (Stipa tenacissima).J Chem Soc(1950)50:1287-1289
    [5]Eda S,Ohnishi A,Kato K Xylan isolated from the stalks of Nicotiana tabacum.Agric Biol Chem(1976)40:359-364
    [6]Montgomery R,Smith F,Srivastava HCStructure of comhull hemicellulose.I.Partial hydrolysis and identification of 2-0-(-D-glucopyranosyluronic acid)-D-.xylopyranose.J Am Chem Soc(1956)78:2837-2839
    [7]Prade RA.Xylanases:from biology to biotechnology.Biotechnol Genet Eng Rev,1996,13:101-131
    [8]Bastawde K B.Xylan structure,microbial xylanases,and their mode of action.World Journal of Microbiology and Biotechnology.1992,9:353-368
    [9]Hayashi,H.,Takagi,K.I.,Fukumura,M.et al.Sequence of xynC and properties of XynC,a major component of the Clostridium thermocellum cellulosome[J].J.Bacteriol,1997,179:4246-4253
    [10]Biely,P.,Kluepfel,D.,Morosoli,R.and Shareck,F.,Mode of action of three endo-beta-1,4-xylanases of Streptomyces lividans[J].Biochim.Biophys.Acta,1993,1162:246一254
    [11]Takami,H.,Nakasone,K.,Takaki,Y.,et al.Complete genome sequence of the alkaliphilic bacterium Bacillus halodurans and genomicsequence comparison with Bacillus subtilis[J」.Nucleic Acids Res,2000,28:4317一4331
    [12]余小红,李里特,江正强,李秀婷.海栖热袍菌极耐高温木聚糖酶B的化学修饰和活性中心[J].应用与环境生物学报,2004,10(3):349-353.
    [13]Kulkarni N,Shendye A,Rao M.Molecular and biotechnological aspects of xylanase[J].FFMS Microbiol Rev,1999,23:411-456.
    [14]刘瑞田,曲音波.木聚糖酶分子的结构区域[J].生物工程进展,1998,8(6);26-28
    [15]Gilbert H.J.and Hazlewood,G.P.Bacterial cellulases and xylanases[J].J Gen.Microbiol,1993,139:187-194
    [16]Bernard Henrissat A.Classification of glycosyl hydrolases based on amino acid sequence similarities[J].Biochem J,1991,280:309-316.
    [17]江正强.海栖热袍菌xynB基因的克隆和表达、重组木聚糖酶的提纯及其酶学性质[D].中国农业大学博士学位论文,2001
    [18]Beg Q K,Kapoor M,Mahajan L,et al.Microbial xylanases and their industrial applications:a review.Appl Microbiol Biotechnol,2001,56:326-338
    [19]Ken K Y,et al.Microbiology Review,1988,52:305-317
    [20]Ko EP,Akatsuka H,Moriyama H et al.Site-directed mutagenesis at aspartate and glutamate residues of xylanase from Bacillus pumilus.Biochem J,1992,288:117-121
    [21]McCarthy AA,Morals DD Bergquist PL et al.Structure of XynB,a highly thermostable beta-1,4-xylanase from Dictyoglomus thermophilum Rt46B.1,at 118 A resolution.Acta Crystallogr D Biol Crystallogr,2000,56(Pt 11):1367-1375
    [22]Moreau A,Roberge M,Manin C et al.Identification of two acidic residues involved in the catalysis of xylanase A from Streptomyceslividans.Biochera J,1994,302:291-295
    [23]Lee YE,Lowe SE,Henrissat B et al.Characterization of the active site and thermostability regions of endoxylanase from Thermoanaerobacterium saccharolyticum B6A-RI.J Bacteriol,1993,175(18):5890-5898
    [24]陈红歌,朱静,梁改芹,等.酸性木聚糖酶产生菌的筛选及产酶条件.微生物学报,1999,39:89-93
    [25]洪枫,陈牧.酶的选择性纯化及酶解制备低聚木糖的研究.林产化学与工业,1999,19(2):49-54
    [26]曲音波,林建强,吴志红,等.短小芽孢杆菌A-30耐碱性木聚糖酶基因的分子生物学研究.应用与环境生物学报.2001,7(1):51-65
    [27]Hongge Chen,Xin Yan,Xinyu Liu et al Purification and Characterization of Novel Bifunctional Xylanase,XynⅢ,Isolated from Aspergillus niger A-25.J.Microbiol.Biotechnol.2006,16(7),1132-1138
    [28]Valenzuela J,Bumann U,Cespedes R.Degradation of chlorophenols by alcaligenes eutrophus JMP134(pJ P4)in bleached kraft mill effluent[J].Appl Environ Microbiol,1997,63:227-232.
    [29]Mohn WW,Stewart GR.Bacterial metabolism of chlorinated dehydroabietic acids occurring in pulp and paper mill effluents[J].Appl Environ Microbiol,1997,63:3014-3020.
    [30]Wong K K,Tan L U,Saddler J.Multiplicity of beta -1,4-xylanase in microorganisms:functions and applications[J].Microbiol Mol Biol Rev,1988,52:305-317.
    [31]连惠芗,汪世华.木聚糖酶的研究与应用.武汉工业学院学报.2006(25)1:42-45
    [32]许正宏,熊筱晶,陶文沂.低聚木糖的生产及应用研究进展[J].食品与发酵工业,2001,28(1):56-59
    [33]杨瑞金,许时婴,王璋.低聚木糖的酶法生产[J].无锡轻工大学学报,2000,19(4):340-344
    [34]王海,李里特.用玉米芯酶法制备低聚木糖[J].食品科学,2002,vol.23,(5):81-83
    [35]吴克,蔡敬民等.黑曲霉木聚糖酶的底物特异性和低聚木糖的生产[J].工业微生物,2002,30(1):18-20
    [36]卓仁禧,罗毅,陶国良.固定化酶技术及其进展,离子交换与吸附,1994,(5):447-452
    [37]蒋中华,张津辉.生物分子固定化技术及应用,北京:化学工业出版社,1998.178
    [38]蒋治良,莫琪,李森,等.酶的固定化及应用[J].广西化工,1994,23(3):18-31
    [39]李彦锋,李军荣,伏莲娣.固定化酶的制备及应用[J].高分子通报,2001:13-23.
    [40]Chibatal.Immobilized Enzymes.New York,London,Sydney,Toronto:John Wiloyand Sons,1978.
    [41]陈陶声,居乃琥,陈石根.固定化酶理论与应用[M].北京:北京轻工业出版社,1987.
    [42]彭志英,食品酶学导论.北京:中国轻工业出版社,2002.1
    [43]禹邦超,刘德立.应用酶学导论.武汉:华中师范大学出版社,1995.11
    [44]杨接非.国外医药一合成药,生化药制剂分册,1994,15(4):209
    [45]肖海军,赫筱蓉.固定化酶及其应用研究进展,生物学通报,2001,36(7):9-10
    [46]Allal B,Jacques F,J acques L,et al.Adsorption of succinylated lysozyme on hydroxyapatite [J].Journal of Colloid Interface Science,1997,189:37242.
    [47]Quinn Z,Zhou K,Chen X D.Immobilization of β-galactosidase on graphite surface by glutaraldehyde[J].Journal of Food Engineering,2001,48(1):69274.
    [48]Markvicheva,Elena A.Immobilized enzyme and cells in poly(N—vinyl caprolactam)basedhydrogels [J].Applied Biochemical Biotechnology,2000,88(123):1452157.
    [49]Yesim Y.Utilization of bentonite as a support material for immobilization of Candida rugosa lipase[J].Process Biochemist ry,2005,40:215522159.
    [50]Fernando L G,Lorena B,Cesar M,et al.Enzyme stabilization by glutaraldehyde crosslinking of adsorbed proteins on aminated supports[J].Journal of Biotechnology,2005,119:70-75.
    [51]张伟,杨秀山.酶的固定化技术及其应用,自然杂志,2000 22(5):282-286
    [52]P.Bernfeld.Antigens and Enzymes Made Insoluble by Entrapping Them into Lattices of Synthetic Polymers.Science,1963,142:678-679
    [53]K.Buchholz.Macrokinetics and operational stability of immobilized Glucose Oxidase and catalase.Biotechnol.Bioeng.,1978,20:1201 - 1220
    [54]K.N.Kuan.Ultraviolet-sensitive photographic process using Enzyme Biotechnol.Bioeng.,1980,22:1725-1734
    [55]N.Ortega.Optimization of Bera-Glucosidase Entrapment in Alginate and Polyacrylamide Gels,Bioresouoe.Technol.,1998,64:105-111
    [56]赵裕卿.固定化酶应用,应用微生物,1988,4:1-5
    [57]王长生,田玉国.酶的固定化技术,中国调味品,1994,12:7-9
    [58]Mohy M Y,Bencivenga U,Rossi S,et al.Characterization the activity of penicillin G acylase immobilized onto nylon membranes grafted wit h different acrylic monomers by means of γ-radiation [J].Journal of Molecular Catalysis B:Enzymatic,2000:233-244.
    [59]Li S,Fu H,Luo X L,et al.The study of photochemical immobilization of urease on polyether sulfone film surface[J].Journal of Biomedical Engineering,2002,19(1):13216.
    [60]Ratner B D.Plasma deposition for biomedical applications:a brief review[J].Journal of Biomaterial Science Polymembrane,1992,4:3-11.
    [61]Wei Q F.Surface characterization of plasma- treated polypropylene fibers[J].Material Characterization,2004,52:2312235.
    [62]Puleo D A,Kissling R A,Sheu M S.A technique to immobilize bioactive proteins,including bonemorphogenetic protein24(BMP—4),on titanium alloy[J].Biomaterial,2002,23:2079-2087.
    [63]Cong L,Kaul R,Dissing U,et al.A model study on Eudragit and polyethyleneimine as soluble carriers of α-amylase for repeated hydrolysis of starch.Journal of Biotechnology,1995,42:75-84
    [64]Chen S H,Yen Y H,Wang C L,et al.Reversible immobilization of lysozyme via coupling to reversibly soluble polymer[J].Enzyme and Microbial Technology,2003,33:643-649.
    [65]朱洪法.催化剂载体制备及应用技术.北京:石油工业出版社,2002
    [66]Butterfield D A,Joshua C,Liu J L,et al.Elect ron paramagnetic resonance spin label tit ration:a novel method to investigate random and site-specific immobilization of enzymes onto polymeric membranes with different properties[J].Analytica Chimica Acta,2002,470:29-36.
    [67]曹黎明,陈欢林.酶的定向固定化方法及其对酶生物活性的影响,中国生物工程杂志2003,1:22-28
    [68]Dsouza S F,Godbole S S.Immobilization of invertase on rice husk using polyet hylenimine[J].Journal of Biochemical Biophysical Met hods,2002,52:59-62.
    [69]L inqiu Cao,Luuk wan langen.Sheldon,Lmmobilised Enzymes:Carded-bound or Carrierbound or Carder-free[J].Current Opinion in Binotechnology,2003,14:287-394.
    [70]St Clair NL,N aviaMA.Cross-linked Enzyme Crystals as Robust Biocatalysts[J].J Am Chem Soc,1992,114:7314-7316.
    [71]Cao L,van Rantw ijk F,Sheldon RA.Cross-lined Enzyme Aggregater:A Simpe and Effective Method for the Immobization of Penicillin A cylase[J].O rg L ett,2002,2:1361-1364.
    [72]Lopez2Serrano P,Cao L,van Rantw ijk F,et al.Croos-linked Enzyme Aggregates with Enhanced Activity:Application to Lipases[J].BiotechnolL ett,2002,24:1379-1383.
    [73]Ivanido L uiz deM attos,L ilia V L ukachova,LoGorton Thomas Lauress,et al.Evaluation of Glucose Biosensors Based on Prussian Blue and L yophilised,Crytaline and Cross2linked Glucose (CL EC)[J].Talanta,2001,54(5):963-974.
    [74]陈建龙,祁建城,曹仪植等.固定化酶研究进展,化学与生物工程2006,23:7-9
    [75]Majeti N.V.Ravi Kumar.A review of chitin and chitosan applications[J].Reactive and factional polymers,2000,46(1):1
    [76]贾鹏翔,刘雪莹,刘京龙,等.固定化酶及其在化工等领域中的应用[J].皮革科学与工程2002,5:31-37
    [77]徐慧显,李民勤,潘再群,等.葡聚糖磁性毫微粒固定化L-天冬酰胺酶的研究[J].中国生物化学与分子生物学报,1996,12(6):744.
    [78]谢志东,暴奉维,李民勤,等.聚丙烯酸甲酯类大孔树脂对猪胰脂肪酶的固定化研究[J].离子交换与吸附,1995,11(1):24.
    [79]Jolanta Bryjak,Andrzej W.Trochimczuk.Immobilization of lipase and penicillin acylase on hydrophobic acrylic carriers[J].Enzyme and Microbial Technology,2006,39:573-578
    [80]H.W.Yu a,H.Chen,X.Wang,Y.Y.Yang et al.Cross-linked enzyme aggregates(CLEAs)with controlled particles:Application to Candida rugosa lipase[J].Journal of Molecular Catalysis B:Enzymatic,2006,43:124-127
    [81]Chang T M S.Biomedical Application of Proteins.Plenum.Press.New York,1997
    [82]Tao GL,Furusaki S.Synthesis of porous polymer carder and immobilization of a 2chymotrypsin[J].Polymer J,1995,27(2):111.
    [83]刘持标,黄葵,佘益民,等.微胶囊固定化过氧化氢酶的制取及对H_2O_2的分解作用[J].生物化学杂志,1997,13(4):478.
    [84]蔡称心,鞠煜先,陈洪渊.纳米级微带金电极上葡萄糖氧化酶的固定、性质及应用[J].化学学报,1995,53(3):281.
    [85]程发良,莫金垣,戴晓云.聚吡咯为基质的脲酶传感器生物电化学响应[J].高分子学报,1999,(4):417.
    [86]Jegan Roy J,Em ilia A braham T,A bhijith K D,et al.Biosensor for the Determination of Phenols Based on Cross-Linke Enzyme Crysals(CLEC)of Laeease[J].Biosensors and Bioelectronics,2005,21(1):206-211.
    [87]徐晖,王燕,魏密苏.环境工程中固定化酶与固定化微生物的应用[J].沧州师范专科学校学报,2002,18(3):42.
    [88]马秀玲,陈盛,黄丽梅,等.磁性固定化酶处理含酚废水的研究[J].广州化学,2003,28(1):17.
    [89]Rogalski J,Szczodrak J,Dawidowicz A,et al.immobilization of cellulase and D-xylanase complexes from Aspergillus terreus F-413 on controlled porosity glasses.Enzyme Microb Technol,1985,7:395-400
    [90]艾志录,江正强,李里特等.大孔树脂D380固定化橄榄绿链霉菌E-86来源木聚糖酶的研究[J].食品与发酵工业,2004,30(1):10-14
    [91]Abdel Naby M A.Immobiolization of Aspergillus niger NRC 107 xylanase and beta-xylosidase,and propertites of the immobilized enzymes.Appl Biochem Biotechnol,1993,38(1-2):69-81
    [92]Tyagi R,Gupta M N.Immobilization of Aspergillus niger xylanase on magnetic latex beads.Biotechnol Appl Biochem,1995,21:217-222
    [93]Gawande P V,Kamat M Y.Preparation,characterization and application of Aspergillus sp.xylanase immobilized on Eudragit S-100.Journal of Biotechnology.1998,66:165-175
    [94]Sardara M,Roya I,Gupta M N.Simultaneous purification and immobilization of Aspergillus niger xylanase on the reversibly soluble polymer Eudragit~(TM)L-100.Enzyme and Microbial Technology,2000,27(9):672-679
    [95]Gouda M K,Abdel-Naby M A.Catalytic properties of the immobilized Aspergillus tamarii xylanase.microbial.Res.2002,157:275-281
    [96]A ngels Canoa,Cristina Minguillon,Cristina Palet.Immobilization of endo-1,4-_-xylanase on polysulfone acrylate membranes:Synthesis and characterization.Journal of Membrane Science.2006,280:383-388
    [97]Andrei Sarbu,Maria Norberta de Pinho,Maria do Ros'ario Freixo et al.New method for the covalent immobilization of a xylanase by radical grafting of acrylamide on cellulose acetate membranes.Enzyme and Microbial Technology.2006,39:125-130
    [98]Zhilu Ai,Zhengqiang Jiang,Lite Li et al.Immobilization of Streptomyces olivaceoviridis E-86 xylanase on Eudragit S-100 for xylo-oligosacchafide production.Process Biochemistry,2005,40:2707-2714
    [99]朱启忠.壳聚糖固定化半纤维素酶的研究.生物化学与生物物理进展,2000,27(3):274-277
    [100]朱启忠.青霉菌胞外半纤维素酶的固定化研究.微生物学杂志,2000,20(2):56-57
    [101]朱启忠,韩晓弟,赵洪等.链霉菌Strz一6木聚糖酶的纯化和固定化研究,工业微生物,2006,36(2):41-43
    [102]蔡敬民,吴克,张洁等.脱乙酰壳聚糖固定化宇佐美曲霉木聚糖酶及固定化酶的性质和应用.中国生物化学和分子生物学学报,2002,18(5):548-522
    [103]Bailey M J,Biely P,Poutanen K.Interlaboratory testing of methods for assay of xylanase activity.J.Biotechnol.1992,23:257-270
    [104]陈毓荃.生物化学实验方法和技术.科学出版社,2002
    [105]任玲玲,何静,马润宇等.固定化青霉素酰化酶的新载体.[J]北京化工大学学报.2002,29(1),64-67
    [106]刘红霞,段雪,马润宇.层状材料水滑石固定青霉素酰化酶的研究.[J]北京化工大学学报.2002,29(3),9-11
    [107]魏荣卿,沈斌,刘晓宁等.壳聚糖载体柔性固定化木瓜蛋白酶.[J]过程工程学报.2005,5(2),183-187
    [108]Dumitriu S,Chornet E.Immobilization of Xylanase in Chitosan-Xanthan Hydrogels.Biotechnol.Prog.1997,13:539-545

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