【作者】 王海；

【导师】 李里特；

【作者基本信息】 中国农业大学 ， 食品科学与工程， 2002， 博士

【摘要】 近年来，随着生活水平的不断发展，人们对饮食不仅注重其色、香、味、营养价值，而且还要求具有保健功能，因此功能性食品越来越受到人们的青睐。功能性低聚糖因具有独特的生理功能，特别是能促进肠道内双歧杆菌的增殖，有益于肠健康而成为一种重要的功能性食品基料，并已引起全世界的广泛关注。低聚木糖极难被消化吸收，肠道内残存率高，具有极好的双歧杆菌增殖性，其选择利用性高于其它功能性低聚糖。低聚木糖亦称木寡糖，由2～7个D-木糖以β-1，4-木糖苷键结合而成，主要是以富含木聚糖的植物资源，如木屑、玉米芯、棉籽壳、稻草和蔗渣等为原料，经内切型木聚糖酶水解制得。中国农业大学李里特教授主持的玉米芯酶法制备低聚木糖工业化生产与开发研究，已取得成功。玉米芯酶法制备低聚木糖工业化生产及其完善对充分利用可再生资源，保护环境，增加农业附加值，降低产品成本是十分必要的。 本论文首先在研究不同木聚糖作碳源诱导Streptomyces E-86菌株(简称sp.E-86菌株)产高活性木聚糖酶、sp.E-86菌株产木聚糖酶和商品半纤维素酶在4℃各粉状玉米芯木质纤维上的吸附动力学和吸附等温线、不同量sp.E-86菌株产木聚糖酶在55℃下和商品半纤维素酶在40℃下对各粉状玉米芯木质纤维酶解的基础上，对不同木聚糖诱导sp.E-86菌株产木聚糖酶机理、吸附机理、酶解机理做了深入研究，提出并建立了等温吸附数学模型和酶解反应数学模型。其主要内容有： 1.研究了不同碳源对sp.E-86菌株在斜面上生长情况以及对sp.E-86菌株产高活性木聚糖酶诱导性能的影响，并分析了不同碳源的组成和结构对sp.E-86菌株产高活性木聚糖酶的影响，阐明产木聚糖酶机理。得出结论：1)以麸皮和马铃薯混合提取液为斜面培养基碳源，对sp.E-86菌株斜面生长与采用玉米芯木聚糖为碳源相比要好，以麸皮和马铃薯为碳源的斜面培养基可完全替代玉米芯木聚糖斜面培养基；2)首次借助于薄层层析、离子色谱和红外光谱及各木聚糖溶解率对玉米芯木聚糖和商品桦木木聚糖的结构进行测定。水不溶性玉米芯木聚糖主要为直链型木聚糖、醇不溶性玉米芯木聚糖有直链和支链型木聚糖和商品桦木木聚糖主要为支链木聚糖，木聚糖支链上的单糖和木聚糖用量对诱导sp.E-86菌株产木聚糖酶有很大影响；3)1.5％水不溶性玉米芯木聚糖对sp.E-86菌株产木聚糖酶表现出极强的诱导能力，其作为碳源所产木聚糖酶的酶活约为1.5％桦木木聚糖的3倍，是2.0％醇玉米芯不溶性木聚糖的4倍；4)提出了木聚糖结构对诱导sp.E-86产木聚糖酶有影响，分析了sp.E-86菌株以水不溶性玉米芯木聚糖、醇不溶性玉米芯木聚糖和桦木木聚糖作碳源诱导木聚糖酶的历程。在5天的发酵时间内，碳源为1.5％时，木聚糖诱导Sp.E-86菌株产的木聚糖酶酶活力都是随着时间增加的，水不溶性玉米芯木聚糖增加最快，其次是桦木木聚糖，醇不溶性玉米芯木聚糖最慢；5)随着发酵时间的增加，sp.E-86产木聚糖酶液的pH值总体呈现上升趋势，发酵初期pH逐渐增加，后期pH处于平缓。 2.首次建立了木聚糖酶与各粉状玉米芯木质纤维的吸附体系，在4℃下，分别研究了sp.E-86菌株产木聚糖酶和商品半纤维素酶在各粉状玉米芯木质纤维上的吸附动力学和吸附等温线。得出：1)sp.E-86菌株产木聚糖酶在这些粉状木质纤维上吸附平衡所需时间均不超过60min，商品半纤维素酶在这些粉状木质纤维上吸附平衡所需时间均不超过10min；2)设计了在4℃，吸附90min的条件下，sp.E-86菌株产木聚糖酶和商品半纤维素酶在粉状木质纤维上的吸附实验，等温线都符合“S”型吸附等温线特征；3)sp.E-86凶株产木聚糖酶的吸附量远大于商品半纤维素酶的吸附量。这说明了酶在底物上的吸附与酶种类及底物结构有关。 3.基于sp.E-86菌株产木聚糖酶和商品半纤维素酶在粉状木质纤维上的吸附等温线都符合“S”型吸附等温线特征，分析了sp.E-86菌株产木聚糖酶和商品半纤维素酶在粉状木 博1－学位论义 论义摘奖 质纤维上的吸附机理，提出了二点假定条什，推导出了吸附数学模型，并通过Rosenbroch 和 Quasi－＼ewton算法与实验结果拟和，纶果非常满意。 4．以 SP E－86菌株产木聚糖酶和商品个纤维素酶在粉状木质纤维上的吸附等温线为 基础，以吸附量刚好趋于不变或变化缓慢时的酶活量为基准，分别取小了基准酶活量、等 于基准酶活量和人于基准酶活量进行酶水解反应，用 PLC和 HPLC对酶解产物进行分析。 得出：l）当酶活量小于或稍高于基准酶活量时，酶活量越高，在一定时间内得到的总糖 和直接还原糖量越多，但当酶活量超过基准酶活量时，酶活量越高，在一定时间内得到的 总糖和直接还原糖量与基准酶活量的差别不大：2）sp．卜86产木聚糖酶和商品半纤维素 酶酶解玉米芯木聚糖、全玉米芯纤维素和玉米芯粉所得总糖和直接还原糖量是玉米芯木聚、糖＞全玉米芯纤维素＞玉米芯粉，sp．E－8更多还原

【Abstract】 With the uninterrupted growth of living standard, people recently pay attention not only to thefood’s colof, savory flavor and nutritive value but also to health care function. The functionalfOods have been become popular. Since they have some specific physiological functions, such aJspromoting the multiplication of BytdObacleria in intestines, keeping a good healthy for peopIes,the functionaI oligosaccharides have been attached impohant to by the researchers all over theworld. The functional oligosaccharides have become a kind of important functional fOods’ basematerials. It’s very difficult for xylooligosaccharide’s digestion in intestines. The intestinalsurvivors of xylooligosaccharides are too much, and can keep a good multiplication forBpobacteria. The utiliZaion of the xylooligosaccharide is the highest among the otheroligosaccharides. A xylooligosaccharide is composed of 2--7 xyIoses. The link between themolecules is 6-l,4 xylosidate band. lt can be prepared by 0-xylanase reaction with sawdust,corncob, cotton seed hull, rice straw or bagasse. Preparation of xylooligosaccharides fromcorncobs by enZyme system done by Li-Lite who is professor of Sino-Japanese Food ResearchCentef, Chinese Agriculture University has been succeed. It is necessary fOr succeeding andperfecting industrialiZation production of xylooligosaccharides from comcobs by enZyme systemto fully make use of the renewable resources, to protect environment to increase additionalagricultural value and to reduce product cost.This paPer first stUdied the high activity of xylanase from Stroptomyces olivaceovirdis E-86(sp.E-86) on different inducing substrate, the adsorption properties of xylanase from sp.E-86 andshopping hemicellulase on the surfaces of lignocellulosic materials such as cellulose, xylan,lignin, holocellulose and corncob for 90 min at 4C, the hydroIysis of the materials by thedifferent activity amount of xylanase from sp.E-86 at 55C and by shopping hemicellulase at 40t. The embedded research about the mechanisms of producting xylanase from sp.E-86 ondiffereni inducing substr3te, adsorPtion and enZyme reaction had been done. The math models ofthe adsorption isotherms ofxylanase from sp.E-86 and shopping hemicellulase on the surfaces ofthe lignocellulosic materials for 90 min at 4t and the hydrolysis of the materials by thedifferent activity amount of xy1anase from sp.E-86 at 55oC and by shopping hemicellulase at 40OC had been set up. The main detail research contentS are as followingl. The influences of the sp.E-86 strain growing conditions on the different carbon source slantswere observed. The conditions about the xylanase preparation made by the strain growing onthese slants were studied. At the same time, the activities of xylanase from sp.E-86 by differentinducing xyIans were studied too. The experiments’resuIts were as following’ 1) The growingconditions of the sp.E-86 strain on the blend of the bran eXtractS and the potato eXtracts slantwere as same as that of on the slant of corncob xylan. The slani could instead of the corncobxyIan sIant on the cuIture of the sp.E-86 strain at a1l. 2) Acid hydrolysis, ion chromatography anddissolution rate of water-insoluble corncob xylan, ethanol-insoluble corncob xylan and birchxylan had been done respectively. The water-insoluble corncob xylan was rnainly linear structure.The ethanol-insoluble corncob xylan had ]inear and branched structures. The birch xylan wasmainly branched. It was greatly influence for the branched sugar and the amount of xylan toinduce xylanase from sp.E-86 strain. 3) The 1.5% water-insolubIe corncob xylan showed a verystrong inductivity to the sp.E-86 strain producing xylanase. The enryme activity, which carbonsource was the water-insoluble comcob xylan, was 3 times higher than that of the l.5% birch- l - --tdi l:’;::{,iitk i/ekttoghxylan and 4 times higher than that of the 2.0% ethanol-insoluble corncob xylan. 4) When theamount of c更多还原