The DUF579 proteins GhIRX15s regulate cotton fiber development by interacting with proteins involved in xylan synthesis

Cotton provides the most abundant natural fiber for the textile industry.The mature cotton fiber largely consists of secondary cell walls with the highest proportion of cellulose and a small amount of hemicellulose and lignin.To dissect the roles of hemicellulosic polysaccharides during fiber development,four IRREGULAR XYLEM 15(IRX15)genes,GhIRX15-1/-2/-3/-4,were functionally characterized in cotton.These genes encode DUF579 domain-containing proteins,which are homologs of AtIRX15 involved in xylan biosynthesis.The four GhIRX15 genes were predominantly expressed during fiber secondary wall thickening,and the encoded proteins were localized to the Golgi apparatus.Each GhIRX15 gene could restore the xylan deficient phenotype in the Arabidopsis irx15irx15l double mutant.Silencing of GhIRX15s in cotton resulted in shorter mature fibers with a thinner cell wall and reduced cellulose content as compared to the wild type.Intriguingly,GhIRX15-2 and GhIRX15-4 formed homodimers and heterodimers.In addition,the GhIRX15s showed physical interaction with glycosyltransferases GhGT43C,GhGT47A and GhGT47B,which are responsible for synthesis of the xylan backbone and reducing end sequence.Moreover,the GhIRX15s can form heterocomplexes with enzymes involved in xylan modification and side chain synthesis,such as GhGUX1/2,GhGXM1/2 and GhTBL1.These findings suggest that GhIRX15s participate in fiber xylan biosynthesis and modulate fiber development via forming large multiprotein complexes.

Study on the green extraction of corncob xylan by deep eutectic solvent

Corn as one of the world's major food crops,its by-product corn cob is also rich in resources.However,the unreasonable utilization of corn cob often causes the environmental pollution,waste of resources and other problems.As one of the most abundant polymers in nature,xylan is widely used in food,medicine,materials and other fields.Corn cob is rich in xylan,which is an ideal raw material for extracting xylan.However,the intractable lignin is covalently linked to xylan,which increases the difficulty of xylan extraction.It has been reported that the deep eutectic solvent(DES)could preferentially dissolve lignin in biomass,thereby dissolving the xylan.Then,the xylan in the extract was separated by ethanol precipitation method.The xylan precipitate was obtained after centrifugation,while the supernatant was retained.The components of the supernatant after ethanol precipitation were separated by the rotary evaporator.The ethanol,water and DES were collected for the subsequent extraction of corn cob xylan.In this study,a novel way was provided for the green production of corn cob xylan.The DES was used to extract xylan from corn cob which was used as the raw material.The effects of solid-liquid ratio,reaction time,reaction temperature and water content of DES on the extraction rate of corn cob xylan were investigated by the single factor test.Furthermore,the orthogonal test was designed to optimize the xylan extraction process.The structure of corn cob xylan was analyzed and verified.The results showed that the optimum extraction conditions of corn cob xylan were as follows:the ratio of corn cob to DES was 1:15(g:mL),the extraction time was 3 h,the extraction temperature was 60℃,and the water content of DES was 70%.Under these conditions,the extraction rate of xylan was 16.46%.The extracted corn cob xylan was distinctive triple helix of polysaccharide,which was similar to the structure of commercially available xylan.Xylan was effectively and workably extracted from corn cob by the DES method.This study provided a new approach for high value conversion of corn cob and the clean production of xylan.

超声辅助低温碱提木聚糖及制备低聚木糖

以酒糟为原料,研究超声波辅助碱法对提取木聚糖影响,并考察提取工艺对木聚糖酶制备低聚木糖的影响。响应面实验优化超声波辅助碱提木聚糖,结果表明:在NaOH浓度8%、料液比1∶20、提取温度58℃、超声波功率955W和提取时间20 min条件下,木聚糖提取率为72.31%。通过液相色谱、凝胶色谱和红外光谱分析表明:提取木聚糖样品主要成分为木聚糖,超声处理降低相对分子量和聚合度。酶解制备低聚木糖(XOS),在酶用量为100U/g底物、pH 8.0、50℃时,酶解6 h得率达80%以上,XOS中木二糖-木四糖的含量总和(XOS2-4)占64.5%。XOS为2 mg/mL时,对DPPH自由基清除率为87.3%。本研究通过超声辅助碱溶液降低木聚糖提取能耗和木聚糖相对分子量,有效提高XOS酶解得率。该工艺将有助于提高酿酒副产物酒糟的附加值。

离子色谱电化学检测器测定化妆品中玻色因含量

建立了测定化妆品中玻色因含量的离子色谱分析方法。试样用去离子水分散,超声提取,经Dionex CarboPac MA1 IC(4 mm×250 mm)色谱柱分离后,用电化学检测器,积分安培检测,并采用液相色谱-质谱联用仪定性确证。结果显示,玻色因的线性范围为1~200μg/mL,方法检出限为0.01%(S/N=3),定量限为0.03%(S/N=10),相关系数R^(2)>0.999。在3个浓度加标水平下,方法平均回收率为90.5%~98.5%,相对标准偏差为0.7%~3.7%。该分析方法简便、准确、快速,适用于化妆品样本中玻色因含量的测定。

超声辅助碱法提取甘蔗渣木聚糖的条件优化

甘蔗渣中含有50%以上的综纤维素,是一种极具潜力的功能性低聚木糖资源。本论文研究了甘蔗渣木聚糖的提取条件,比较不同碱法提取方法的提取效果,再通过单因素实验、正交实验优化提取条件,得出最佳的提取方案。相较于高温碱法提取,在同等提取量的情况下,超声波辅助碱法提取的条件更温和、方便,提取效果好。通过单因素实验、正交实验得出最优的提取条件及流程为:甘蔗渣与13%NaOH以料液比为1∶25 g/mL混合后,放入超声功率为240 W的超声波清洗机中,调节超声温度为60℃,恒温超声25 min后,过滤出甘蔗渣且少量多次清洗得到滤液,调节pH为弱酸性,加入等体积95%乙醇,密封沉淀3 h以上,用5 000 r/min离心15 min,提取率可达到36.91%。

糠椴木聚糖提取及纳米木聚糖制备工艺优化

采用碱提法从糠椴中提取木聚糖,通过二次碱液处理制备纳米木聚糖,采用响应面法优化纳米木聚糖制备工艺。结果显示:木聚糖提取最优工艺为碱液质量分数10%,处理温度90℃,处理时间3 h,固液比(g/mL)为1∶15,在此条件下,糠椴可有效提取木聚糖;制备纳米木聚糖的最佳工艺为处理温度59℃,处理时间2 h,碱液质量分数5%,在此条件下制备的纳米木聚糖粒径为9.36 nm,通过透射电子显微镜进一步确定纳米木聚糖粒径为20~40 nm,且形态规则,与纳米激光粒度仪Winner802的测试结果相吻合。本项研究提供了一种有效提取糠椴木聚糖和制备纳米木聚糖的方法,证明了响应面法在工艺参数优化中的可行性。

木质素衍生介孔碳固体酸制备及催化木聚糖制备糠醛

以丙酮/水混合溶剂提取玉米秸秆得到的木质素和间苯三酚为碳前体、乙二醛为交联剂,采用溶剂蒸发诱导自组装法制备了介孔碳(MC),再经磺化合成了木质素衍生介孔碳固体酸(MC-SO_(3)H)。采用SEM、XPS、元素分析仪、N2吸附-脱附和酸度测定对催化剂进行了表征,以木聚糖转化率和糠醛产率为指标,考察了MC-SO_(3)H催化降解木聚糖制备糠醛的反应条件,探究了MC-SO_(3)H失活的原因。结果表明,MC-SO_(3)H具有120.74 cm^(2)/g的介孔比表面积和4.15 nm的平均孔径;在1.0 g木聚糖、1.0 g MC-SO_(3)H、30 mLγ-戊内酯为溶剂、反应温度180℃、反应时间10 min的最佳反应条件下,木聚糖转化率和糠醛产率分别为90.0%和79.5%。MC-SO_(3)H的总酸度(2.06 mmol/g)和—SO_(3)H酸度(0.82 mmol/g)是其催化活性的主要来源,未反应的木聚糖及反应过程中形成的降解物等在催化剂上附着造成了MC-SO_(3)H的总酸度和—SO_(3)H酸度的下降,是其失活的主要原因。在以木糖代替木聚糖评价MC-SO_(3)H稳定性的实验中,重复使用4次后,木糖转化率和糠醛产率仍可达89.5%和66.8%。

一种β-1,3-木聚糖特异性结合蛋白的克隆表达、性质研究及其应用

β-1,3-木聚糖是紫菜等海藻中的重要结构多糖。多糖结合蛋白是多糖研究的关键工具,常被用作探针服务于多糖的原位分析;其中,碳水化合物结合结构域(carbohydrate-binding module,CBM)是一类被广泛应用的多糖结合蛋白。该研究从公共基因数据库中挖掘得到了一条潜在具有β-1,3-木聚糖结合能力的CBM6家族序列,并对该序列进行了异源表达及亲和纯化,得到电泳纯蛋白,命名为VaCBM6。该蛋白表现出对β-1,3-木聚糖的特异性结合能力,结合常数为3.0×10^(5)(mol/L)^(-1)。将该蛋白与绿色荧光蛋白EmGFP融合表达构建出首个β-1,3-木聚糖的特异性荧光探针,以该探针为工具实现了紫菜中β-1,3-木聚糖的荧光显微观察,证实了VaCBM6在β-1,3-木聚糖原位分析中的良好应用潜力。VaCBM6的挖掘与表征为β-1,3-木聚糖的研究与开发提供了良好工具。

木聚糖酶在青贮及反刍动物日粮中的应用

青贮饲料与反刍动物日粮中木质纤维素占比高,直接进行利用会造成能量流失。酶制剂在青贮或日粮中应用广泛,通过酶制剂预处理可提高饲料的利用效率。木聚糖酶与其它酶制剂混合添加可有效降解青贮中的纤维含量,增加可代谢糖含量,有利于微生物生长,促进青贮发酵,进而提高青贮饲料的利用效率。在反刍动物日粮中,木聚糖酶可以辅助瘤胃微生物分解饲料中的纤维成分,改善瘤胃发酵环境,使反刍动物获得更多的能量来供其生长和代谢,进而提升反刍动物的生产性能。本文介绍了木聚糖与木聚糖酶,通过综述木聚糖酶在青贮及反刍动物日粮中应用,阐释了木聚糖酶在青贮与反刍动物日粮中的添加量、利用效果,为后续木聚糖酶的利用提供理论参照。

用于锂离子电池高压LNMO正极的瓜尔胶-木聚糖粘结剂

具有尖晶石结构的镍锰酸锂(LNMO)被认为是最有前景的正极材料之一,然而高工作电压会严重影响LNMO正极的循环寿命,导致在充放电过程中容量快速衰减、循环性能较差。针对锂离子电池无钴正极材料镍锰酸锂(LNMO)在高电压下的界面不稳定的缺点,开发了适用于5.0 V高压LNMO正极的木聚糖-瓜尔胶复合粘结剂。研究结果表明,瓜尔胶与木聚糖通过交联形成酯基,使粘结剂具备良好的机械性能;与PVDF粘结剂相比,使用复合粘结剂的LNMO的循环稳定性得到了显著提高,是具有应用前景的锂离子电池高压正极粘结剂。

Optimizing hemicelluloses pre-extraction in eucalyptus kraft pulping:A pathway towards enhancing pulp mill biorefineries

A critical pathway towards enhancing pulp mill biorefineries is to integrate the extraction and utilization of hemicelluloses into the pulping processes.Hence,an industrial pre-extraction strategy for hemicelluloses targeting eucalyptus kraft pulping process was developed.Alkaline solution or pulping white liquor was used to pre-extract hemicelluloses before the actual pulping process.The response surface methodology(RSM)technique was applied to investigate the most suitable conditions to maximize the yield of these hemicelluloses while simultaneously minimizing the damage to pulp yields and properties.Temperature(105 to 155℃),alkali concentration(3%to 8%),sulfidity(20%to 30%)and retention time(19 to 221 min)were combined to evaluate their effects on hemicellulose yields and chemical structures.The optimal pre-extraction conditions identified in this work(5.75%NaOH concentration,25%sulfidity at 135℃for 60 min)successfully allowed recovering 4.8%of hemicelluloses(based on the wood dry mass)and limited damages to pulp yields and properties.The cellulose content in pulp can even be increased by about 10%.Hemicellulose emulsification properties were also evaluated,which were comparable to synthetic emulsifiers.This study provides an industrial pathway to effectively separate and utilize wood hemicelluloses from the pulping process,which has the potential to improve the economy and material utilization of pulp and paper mills.

毛竹笋木聚糖提取工艺优化及其抗氧化活性分析

为了实现竹笋加工废弃物的资源转化与利用,采用碱提醇沉法提取毛竹笋中的木聚糖,通过单因素试验和正交试验优化提取工艺,利用高效液相色谱法和傅里叶变换红外光谱分析毛竹笋木聚糖的理化性质,并通过DPPH法和ABTS法评价毛竹笋木聚糖的体外抗氧化活性。结果表明:在提取时间3.5 h、碱液质量浓度0.1 g·mL^(−1)、料液比1∶25,提取温度100℃的条件下,毛竹笋木聚糖提取率最高,可达20.86%。单糖组成和FT-IR分析表明木糖可能是构成毛竹笋木聚糖的主要成分。体外抗氧化性试验表明毛竹笋木聚糖具有一定的抗氧化活性,当浓度为8 mg·mL^(−1)时,其对DPPH自由基的清除率达到94.75%,IC_(50)值为1.0 mg·mL^(−1);当浓度为20 mg·mL^(−1)时,其对ABTS自由基的清除率为93.09%,IC_(50)值为3.85 mg·mL^(−1)。

离子色谱法测定化妆品中不同构型羟丙基四氢吡喃三醇的含量

建立了一种离子色谱测定S构型与R构型羟丙基四氢吡喃三醇的方法,同时建立了液相色谱串联质谱法确证阳性样品的方法,并用该方法对市面上标签中标注含有羟丙基四氢吡喃三醇的化妆品进行了检测。样品经提取过滤后,以100 mmol/L氢氧化钠溶液为流动相,用CarboPac MA1(250 mm×4 mm×1.6μm)色谱柱分离,离子色谱-电化学检测器进行定性和定量分析。结果表明,S构型与R构型羟丙基四氢吡喃三醇的质量浓度与峰面积之间呈良好线性关系(R^(2)>0.999),检出限为质量分数0.001%,定量限为质量分数0.003%。在高、中、低3种加标水平下,回收率为88.09%~110.1%,精密度在1.02%~7.62%(n=6)。该方法前处理简便快捷、灵敏度高、基质干扰小,适用于化妆品中S构型与R构型羟丙基四氢吡喃三醇的同时检测。

一款轻奢香氛护手霜的制备及其功效研究

以奥婷敏、玻色因、重组胶原蛋白为主要活性成分,利用水包油(O/W)乳化体系制备出一款轻奢香氛护手霜。考察了乳化剂、增稠剂、乳化温度和时间对产品性能的影响,并对所制备产品进行pH值、耐热耐寒性及留香时间等检测,通过人体功效评价试验和受试者主观评价对其进行功效评估。结果显示该护手霜有良好的稳定性和留香效果,可以有效改善皮肤粗糙干燥状况,修护皮肤屏障,增强皮肤弹性,减轻皮肤纹理和皱纹,同时也具有较好的保湿作用。

Effects of protein and lignin on cellulose and xylan anaylses of lignocellulosic biomass

Interactions of lignocellulosic components during fiber analysis were investigated using the highly adopted compositional analysis procedure from the National Renewable Energy Laboratory（NREL）,USA.Synthetic feedstock samples were used to study the effects of lignin/protein,cellulose/protein,and xylan/protein interaction on carbohydrate analysis.Disregarding structural influence in the synthetic samples,lignin and protein components were the most significant（P〈0.05）factors on cellulose analysis.Measured xylan was consistent and unaffected by content variation throughout the synthetic analysis.Validation of the observed relationships from synthetic feedstocks was fulfilled using real lignocellulosic feedstocks：corn stover,poplar,and alfalfa,in which similar results have been obtained,excluding cellulose analysis of poplar under higher protein content and xylan analysis of alfalfa under higher protein content.The results elucidated that according to their protein and lignin contents of different lignocellulosic materials,accuracy of the NREL method on cellulose and xylan analyses could be improved by applying a stronger extraction step to replace water/ethanol extraction.

High Oxygen Nanocomposite Barrier Films Based on Xylan and Nanocrystalline Cellulose

The goal of this work is to produce nanocomposite film with low oxygen permeability by casting an aqueous solution containing xylan,sorbitol and nanocrystalline cellulose.The morphology of the resulting nanocomposite films was examined by scanning electron microscopy and atomic force microscopy which showed that control films containing xylan and sorbitol had a more open structure as compared to xylan-sorbitol films containing sulfonated nanocrystalline cellulose.The average pore diameter,bulk density,porosity and tortuosity factor measurements of control xylan films and nanocomposite xylan films were examined by mercury intrusion porosimetry techniques.Xylan films reinforced with nanocrystalline cellulose were denser and exhibited higher tortuosity factor than the control xylan films.Control xylan films had average pore diameter,bulk density,porosity and tortuosity factor of 0.1730 μm,0.6165 g/ml,53.0161% and 1.258,respectively as compared to xylan films reinforced with 50% nanocrystalline cellulose with average pore diameter of 0.0581 μm,bulk density of 1.1513 g/ml,porosity of 22.8906% and tortuosity factor of 2.005.Oxygen transmission rate tests demonstrated that films prepared with xylan,sorbitol and 5%,10%,25% and 50% sulfonated nanocrystalline cellulose exhibited a significantly reduced oxygen permeability of 1.1387,1.0933,0.8986 and 0.1799 cm^3×μm/m^2×d×k Pa respectively with respect to films prepared solely from xylan and sorbitol with a oxygen permeability of 189.1665 cm^3×μm/m^2×d×k Pa.These properties suggested these nanocomposite films have promising barrier properties.

Paddy Husk as Support for Solid State Fermentation to Produce Xylanase from Bacillus pumilus

To optimize culture conditions for xylanase production by solid state fermentation （SSF） using Bacillus pumilus, with paddy husk as support, solid medium contained 200 g of paddy husk with 800 mL of liquid fermentation medium [xylan, 20.0 g/L; peptone, 2.0 g/L; yeast extract, 2.5 g/L; K2HPO4, 2.5 g/L; KH2PO4, 1.0 g/L; NaCl, 0.1 g/L; （NH4）2SO4, 2.0 g/L, CaCl2-2H2O, 0.005 g/L; MgCl2.6H2O, 0.005 g/L; and FeCI3, 0.005 g/L] at pH 9.0 was applied. The highest xylanase activity （142.0 ±0.47 U/g DM] was obtained on the 6th day at 30℃ The optimized paddy husk to liquid fermentation medium ratio was 2：9, and the optimized culture temperature was 40℃. When commercial Birchwood xylan was replaced with different concentrations of corncob, xylanase production was maximized （224.2 U/g DM） in the medium with 150 g/L corncob. Xylanase production was increased by sucrose, fructose and arabinose, whereas reduced by glucose, galactose, lactose and amylose. When organic nitrogen sources were replaced with locally available nitrogen sources such as groundnut powder or sesame seedcake powder or coconut seedcake powder or soy meal powder, the highest xylanase production （290.7 U/g DM） was obtained in the medium with soy meal powder and 16.0 g/L of soy meal powder was the optimum （326.5±0.34 U/g DM）. Based on the optimization studies, B. pumilus produced 2.3 times higher xylanase activity. The medium cost was reduced from 2 458.3 to 178.3 SLR/kg and the total activity which could be obtained from 1 kg of the medium was increased from 48 624 to 220 253 Units.

Global identification of genes associated with xylan biosynthesis in cotton fiber

Background:Mature cotton fiber secondary cell wall comprises largely of cellulose(>90%)and small amounts of xylan and lignin.Little is known about the cotton fiber xylan biosynthesis by far.Results:To comprehensively survey xylan biosynthetic genes in cotton fiber,we identified five IRX9,five IRX10,one IRX14,six IRX15,two FRA8,one PARVUS,eight GUX,four GXM,two RWA,two AXY9,13 TBL genes by using phylogenetic analysis coupled with expression profile analysis and co-expression analyses.In addition,we also identified two GT61 members,two GT47 members,and two DUF579 family members whose homologs in Arabidopsis were not functionally characterized.These 55 genes were regarded as the most probable genes to be involved in fiber xylan biosynthesis.Further complementation analysis indicated that one IRX10 like and two FRA8 related genes were able to partially recover the irregular xylem phenotype conferred by the xylan deficiency in their respective Arabidopsis mutant.We conclude that these genes are functional orthologs of respective genes that are implicated in GX biosynthesis.Conclusion:The list of 55 cotton genes presented here provides not only a solid basis to uncover the biosynthesis of xylan in cotton fiber,but also a genetic resource potentially useful for future studies aiming at fiber improvement via biotechnological approaches.

Facile Approach for Preparation of Xylan-based Double-network Hydrogels

In this study,xylan-based double-network(DN)hydrogels(xylanbased DN gels)with excellent mechanical properties were prepared using acrylic acid and acrylamide(AM)based on a DN approach.The first layer network was obtained by grafting and crosslinking polyacrylic acid(PAA)molecular chains onto xylan with ammonium persulfate(APS)as the initiator and N,N'-methylenebisacrylamide(MBA)as the crosslinking agent;this network was subsequently immersed into an aqueous AM monomer in the presence of APS and MBA for the preparation of the second layer network.The results showed that the double networks were crosslinked by covalent bonds and that the mechanical properties of the xylan-based DN gels were enhanced.Thus,the xylan-based DN gels exhibited a maximum compression stress of 24.9 MPa.The xylan-based DN gels could also recover 97%of their original height after 15 repeated compression cycles;this indicates that the xylan-based DN gels possessed high resistance to friction and wear.Therefore,the prepared xylan-based DN gels have considerable potential for tissue engineering applications.

Optimization of Microwave Assisted Alkaline Extraction of Xylan from Birch Wood Using Response Surface Methodology

The main purpose of this study was to optimize microwave assisted alkaline extraction of the hemicellulose, xylan, from birch wood. The simultaneous effects of process variables such as time (10 - 30 minutes), concentration of sodium hydroxide solution (4 - 8 wt%), solid to liquid ratio (1:8 to 1:20, g:mL), and sample size (5 - 10 g) on the temperature of the wood slurry, wood dissolution, and yield of extraction were evaluated. A central composite design (CCD) and response surface methodology (RSM) were used for the optimization of the extraction process. Based on the CCD, quadratic models were developed to correlate the extraction process variables with the responses such as temperature of wood slurry, wood dissolution, and yield of xylan and the models were analyzed using appropriate statistical methods (ANOVA). Statistical analysis showed that all the models developed were found to be adequate for the prediction of the respective responses. Optimization of the process was performed using a numerical optimization available in the software to maximize the yield of xylan and the optimum process variables for the maximum yield of xylan was found to be: 10 g of wood fibres, 8 wt% of NaOH solution, 1:10 solid to liquid ratio (g:mL) and 25 minutes of irradiation time. About 72.5% of the xylan present in the birch wood was extracted using the optimized extraction parameters.