纤维素酶酶解苇浆纤维微观结构和结晶结构的变化

采用红外光谱(IR)、X射线衍射分析和扫描电镜对在纤维素酶解进程中苇浆纤维素大分子的结构及纤维形态的变化进行了研究.研究结果表明,纤维素酶酶解进程中,纤维素大分子的晶型没有改变,但结晶度呈现周期性变化,微晶尺寸略有降低.在酶解初期,纤维素酶不仅作用于纤维素无定形区,也开始作用在纤维素结晶区表面;在酶解中、后期,纤维素酶对纤维素结晶区和无定形区的作用呈现周期性变化.纤维素酶解过程中纤维表面呈现周期性"剥皮"现象,并且在纤维表面出现孔洞和沟槽,在孔洞处纤维易断裂,导致纤维长度和粗度的降低.     

酶洗中纤维素酶的作用方式与途径的探讨

应用电子显微镜对酶洗前后棉、麻织物纤维的结构变化进行多方面扫描。根据得到的一系列电镜图，依据酶学工作者对纤维素酶组分与性能的研究，纡维素酶降解纤维素的先决条件是，酶与纤维素（底物）相互接触形成复合物而后酶水解；根据棉、麻纤维的结构、组成不同，探讨酶洗中纤维素酶的作用方式与途径，并以此简释酶洗给棉、麻织物带来高附加价值的性能。     

SDS-Sulfite Increases Enzymatic Hydrolysis of Native Sorghum Starches

The sodium dodecyl sulfate (SDS) starch isolation procedure is often used to remove efficiently the surrounding and surface protein of starch granules in order to obtain a pure starch sample. In this study the changes in enzymatic hydrolysis of sorghum starch granules due to SDS-sulfite solution treatment were investigated. As SDS-sulfite solution soak time increased, enzymatic hydrolysis rate increased and the Michaelis-Menten pattern of enzymatic reaction did not change. The degree of this effect differed among starches from three sorghum cultivars. The effect of SDS-sulfite solution treatment on enzymatic hydrolysis became negligible after the treated starch samples were partially hydrolyzed. The adsorption of α-amylase onto the starch granules also increased with SDS-sulfite solution treatment and was highly correlated with hydrolysis rate. The different effects of SDS-sulfite solution on enzymatic hydrolysis of the three sorghum starches were related to the properties of the amorphous regions in starch granules.     

The Effects of Enzyme Hydrolysis on the Properties of Potato,Cassava and Amaranth Starches

X-ray diffraction method and differential scanning calorimetry were used to study the effects of enzyme hydrolysis on physico-chemical properties of potato, cassava and amaranth starches. Various hydrolysis procedures and different sources of enzymes were employed. The highest percentage of hydrolysis was obtained using the bacterial thermostable α-amylase following by the saccharification with amyloglucosidase. Enzyme treatment showed decrease in the degree of crystallinity of all hydrolyzed starch samples of A-type crystals. B-and C-types were weakened upon enzymatic hydrolysis at 60°C and completely dissappeared at 100°C. The gelatinization endotherm decreased for samples with low degree of crystallization and disappeared in samples with amorphous stage.     

Lignin Interaction with Cellulase during Enzymatic Hydrolysis

The conversion of lignocellulosic biomass into biofuels or biochemicals typically involves a pretreatment process followed by the enzyme-catalyzed hydrolysis of cellulose and hemicellulose components to fermentable sugars. Many factors can contribute to the recalcitrance of biomass, e.g., the lignin content and structure, crystallinity of cellulose, degree of fiber polymerization, and hemicellulose content, among others. However, nonproductive binding between cellulase and lignin is the factor with the greatest impact on enzymatic hydrolysis. To reduce the nonproductive adsorption of enzymes on lignin and improve the efficiency of enzymatic hydrolysis, this review comprehensively summarized the progress that has been made in understanding the interactions between lignin and enzymes. Firstly, the effects of pretreatment techniques on lignin content and enzymatic hydrolysis were reviewed. The effects of lignin content and functional groups on enzymatic hydrolysis were then summarized. Methods for the preparation and characterization of lignin films were assessed. Finally, the methods applied to characterize the interactions between lignin and cellulase were reviewed, and methods for decreasing the nonproductive binding of enzymes to lignin were discussed. This review provides an overview of the current understanding of how lignin hinders the enzymatic hydrolysis of lignocellulosic biomass, and provides a theoretical basis for the development of more economical and effective methods and additives to reduce the interaction of lignin and enzymes to improve the efficiency of enzymatic hydrolysis.     

液态发酵原位酶解糖化水稻秸秆工艺优化

为探究以原位酶解方式整合产酶菌株的发酵条件和酶解条件差异的可行性,以木质纤维结构典型的水稻秸秆为对象,里氏木霉为产酶微生物,通过研究液态发酵原位酶解糖化水稻秸秆,对发酵过程和酶解过程协同控制条件进行优化.结果 显示,最优产酶发酵条件为水稻秸秆添加量30 g/L,发酵温度30℃,初始pH 6.5,发酵时间48 h;最优酶...     

Evaluation of pretreatment with Pleurotus ostreatus for enzymatic hydrolysis of rice straw

The effects of biological pretreatment of rice straw using four white-rot fungi (Phanerochaete chrysosporium, Trametes versicolor, Ceriporiopsis subvermispora, and Pleurotus ostreatus) were evaluated on the basis of quantitative and structural changes in the components of the pretreated rice straw as well as susceptibility to enzymatic hydrolysis. Of these white-rot fungi, P. ostreatus selectively degraded the lignin fraction of rice straw rather than the holocellulose component. When rice straw (water content of 60%) was pretreated with P. ostreatus for 60 d, the total weight loss and the degree of Klason lignin degraded were 25% and 41%, respectively. After the pretreatment, the residual amounts of cellulose and hemicellulose were 83% and 52% of those in untreated rice straw, respectively. By enzymatic hydrolysis with a commercial cellulase preparation for 48 h, 52% holocellulose and 44% cellulose in the pretreated rice straw were solubilized. The net sugar yields based on the amounts of holocellulose and cellulose of untreated rice straw were 33% for total soluble sugar from holocellulose and 32% for glucose from cellulose. The SEM observations showed that the increase in susceptibility of rice straw to enzymatic hydrolysis by pretreatment with P. ostreatus is caused by partial degradation of the lignin seal. When the content of Klason lignin was less than 15% of the total weight of the pretreated straw, enhanced degrees of enzymatic solubilization of holocellulose and cellulose fractions were observed as the content of Klason lignin decreased.     

纤维素酶酶解啤酒糟的工艺研究

该文采取纤维素酶处理啤酒糟,旨在酶解啤酒糟中的纤维素。采用直接滴定法测定啤酒糟酶解液中的还原糖含量,通过单因素试验初步研究不同料液比、酶解时间、反应初始pH值、酶解温度、纤维素酶添加量等因素对酶解液中还原糖含量的影响。在此基础上,采用三因素三水平的正交试验优化其工艺条件。结果表明,纤维素酶酶解啤酒糟的最佳工艺条件为反应初始pH 6.0,酶添加量2.5%,酶解时间4 h。此时,酶解液中的还原糖含量为3.65 mg/mL。     

纤维素酶在不同长度纤维上的吸附行为

纤维素酶在纤维表面上的吸附是纤维素水解糖化的第一步,探讨了纤维素酶在不同长度纤维上的吸附行为。纤维素酶在纤维上吸附约60 min后可达到平衡,且吸附量随初始酶用量的增加而增多。吸附过程遵循Langmuir等温吸附,且纤维素酶在短纤维上具有最大的吸附量,但在长纤维上具有最大的Langmuir吸附平衡常数,说明纤维素酶在长纤维上能更快地达到吸附平衡。对吸附热力学常数的计算表明,纤维素酶吸附是自发、放热过程,且不可逆吸附。纤维素酶在48目纤维上有最大的吸附焓变,在28目纤维上有最大的吸附熵变。     

即食莲泥加工工艺的研究

为充分利用扣莲生产的剩余产物(莲子头),开发一种营养丰富的即食莲泥制品。在对莲子头主要成分进行分析的基础上,采用纤维素酶进行酶解,并优化莲泥的酶解工艺和产品配方。结果表明,莲子头中纤维素含量是其他部位的1.8倍,是影响莲泥质构和口感的主要因素;纤维素酶酶解的最优工艺为:莲泥pH 4.5~5.0,底物浓度为45%,纤维素酶添加量为12 000 U/g,酶解温度为55℃,酶解时间为3 h;产品配方优化研究表明,添加色拉油12%、牛奶8%、白砂糖18%、银耳全粉0.8%时,即食莲泥感官评价最佳,为95.5分。     

甘薯残渣纤维素酶解工艺研究

研究纤维素酶对甘薯残渣中纤维素降解工艺。以去除淀粉及提取果胶后的甘薯残渣为原料,采用单因素和正交试验方法对甘薯残渣的纤维素酶解工艺进行优化。结果表明,甘薯残渣纤维素酶解最佳工艺为,甘薯残渣固液比1∶25(g/m L),醪液pH 5.0,纤维素酶加入量50 U/g甘薯渣。在50℃下恒温培养16 h。此条件下,甘薯渣中纤维素的转化率可达(4.52±0.14)%。     

纤维素酶水解蔗渣浆的影响因素研究

研究了温度、p H值、加酶量、底物浓度及酶解时间等因素对纤维素水解漂白蔗渣浆的影响 ,试验结果表明 ,最佳水解条件为 :温度 5 0℃ ,p H值 5 .0 ,加酶量 1.0 IU / m g,底物浓度 1.0 % ,酶解时间 2 4h     

沙棘渣制备微晶纤维素的酶解条件优化

沙棘浆加工过程中产生酚酸含量高的果渣,因其苦涩无法被饲料工业大量转化,利用其进行微晶纤维素制备是潜在可行的解决途径。以粗提沙棘渣纤维素为处理对象,使用S10041纤维素酶水解,选取液料比、酶添加量、酶解时间、酶解温度、缓冲液p H值、离心转速、烘干温度及纤维素粉碎度8个因素,通过单因素试验和PlackettBurman因素筛选,并经过最陡爬坡试验和Box-Behnken试验优化了酶解条件,随后对制得的微晶纤维进行结构分析。结果表明:在液料比49∶1(m L/g)、酶添加量68 U/m L、酶解时间1.3 h、离心转速3 640 r/min时制得的沙棘微晶纤维素聚合度为355±1.02,与棉微晶纤维素聚合度最为接近。方差分析表明4个选定因素对指标均产生独立影响,因素交互作用对指标影响不显著(P=0.10)。微观结构显示沙棘微晶纤维表面结构更疏松,红外图谱对比沙棘和棉花两种微晶纤维官能团结构相似。     

Cello-oligosaccharides production from multi-stage enzymatic hydrolysis by lignocellulosic biomass and evaluation of prebiotic potential

Cello-oligosaccharides (COS) are very recent promising water-soluble dietary fibers, which favors several application in food, chemical and pharmaceutical industries. A three-stage enzymatic hydrolysis of cellulose extracted from agroindustrial wastes (sugarcane straw and coffee husk) with the 1,4-β-endoglucanase cellulase of glycoside hydrolase family (GH12) was developed with a processing time of 48 h. Finds evidenced that removal of products (glucose and cello-oligosaccharides) at each stage provided an increase in cello-oligosaccharides enzymatic hydrolysis in yield of approximately 65%. COS promoted growth of Lactobacillus acidophilus and Lactobacillus brevis after 24 h of fermentation, although they have presented low efficiency with Bifidobacterium sp. This multi-stage enzymatic hydrolysis has potential as a successful strategy to reduction enzyme requirements for COS production with prebiotic properties.Industrial relevanceThis work proposes an innovative technology of multi-stage enzymatic hydrolysis using the enzyme adsorbed on the cellulose surface obtained from renewable sources (sugarcane straw and coffee husk). This strategy is potential to increase the COS yield production and possibly make its cost-viable. The study is also relevant due to accessing the growth promotion of a representative selection of probiotic Lactobacillus and Bifidobacterium strains in order to evidence their prebiotic potential to be used as a possible functional ingredient for the pharmaceutical and food industries.     

纤维素酶酶解醇葛根素研究

以提取葛粉后的葛根废渣为研究对象,采用微生物和代谢物酶解提制葛根素,通过高效液相色谱法分析葛根素含量,考察影响葛根素溶出的酶解时间、酶量、pH 值、固液比等参数,探索微生物与底物葛渣间的生物交互作用。实验结果表明：葛根废渣5g,纤维素酶量为底物40%,葛根废渣与水的质量比为1:10,pH 值为5,在30℃酶解36h 后,经乙醇浸提3h,可提取葛根素33.54mg,为葛根废渣的资源化再利用提供实验基础。     

酶解处理对菌菇鳕鱼汤品质的影响及工艺优化

采用分段酶解法处理菌菇鳕鱼汤,以感官评分、氨基酸态氮含量和水解度为评价指标,筛选菌菇鳕鱼汤分段酶解的最适酶组合,并采用单因素试验和正交试验优化酶解的工艺参数.结果 表明,采用纤维素酶与复合蛋白酶组合得到的酶解液具有良好的感官品质与较高的水解度,因此选用这两种酶进行分段酶解,经正交优化后得到一段酶解的最佳工艺为:酶解时间...     

棉织物酶精练理论与效果分析

文章阐述了棉织物酶精练理论、酶处理工艺条件以及酶精练后棉纤维表面的形态变化、吸湿性和染色性,并与碱精练织物的效果进行了实验对比分析。经实验证明,酶精练后的织物不仅能达到碱精练的同样效果,并且具有手感蓬松、柔软、色泽鲜艳、节能、设备简单、工艺流程短、无污水处理等优点。     

纤维素酶在染整加工应用中的若干问题(二)

阐述纤维素酶的作用机理，重点讨论了酶处理中的若干问题，包括搅动对纤维素酶处理效果的影响、表面活性剂对酶水解的影响；减量率与纤维素断裂强力和保水性的关系，以及棉织物酶处理后的性能的综合评价等。     

Structural characterizations of waxy maize starch residue following in vitro pancreatin and amyloglucosidase synergistic hydrolysis

The objective of this work was to determine if in vitro digestion altered the molecular structure and slow digestion property of waxy maize starch. The Englyst testing on partially hydrolysis residual starches showed an increase of RDS accompanied a reduction of RS with increasing time of digestion, while SDS was almost constant. Scanning electron micrographs showed that the pattern of enzymatic hydrolysis was inside-out layer-by-layer digestion. A threefold decrease in the average molecular weight of starch components was observed after α-amylolysis for 120 min. There were increases in the onset temperature, peak temperature and ratio of absorbance 1047/1022 cm⁻¹, while the enthalpy of gelatinization, crystal structure, and crystallinity invaried. These changes suggest simultaneously enzymatic hydrolysis of both crystalline and amorphous regions of starch granule during in vitro digestion. SDS of starch residue also may consists of layered structure of amorphous and crystallite regions and located periphery of starch granules.     

提高木质纤维素酶水解效率的研究进展

利用纤维素酶将预处理后的木质纤维素水解成可发酵性单糖,继而发酵生产所需的液体燃料及其他化工产品,是当前解决资源、环境等难题的有效途径之一.在木质纤维素降解转化工艺中,酶水解效率低、成本高是主要限制因素.如何提高纤维素与纤维素酶的可及度和有效接触面积,从而减少纤维素酶用量及提高酶解效率是水解技术的关键.该文简要归纳了各种提高纤维素酶水解效率方法的最新研究进展,并对其酶解的机理及今后研究的重点进行了分析与展望.