Tween80对稻草水解及同步糖化与发酵产乳酸的影响

在生物转化纤维原料产乳酸的过程中,酶解纤维原料产还原糖是限速步骤。为了获得较高的产物产率,需较高的酶用量,这使大规模酶解废弃纤维原料的成本很高。对吐温80在酶解稻草纤维素产糖,以及耐高温乳酸菌同步糖化发酵稻草产乳酸过程中的作用进行了考察。初步结果表明,吐温80加入可使保持同等程度的水解率所需的酶用量降低,添加0.2 g/g底物的吐温80到酶用量10 FPU/g体系,水解120 h的糖产率为292.2 mg/g,比不加表面活性剂体系的糖产率增加了11%;添加0.7 g/L的吐温80进行同步糖化与发酵72 h,能使乳酸产量提高24.2%。     

化学法预处理麦秸纤维素的效果比较研究

以麦秸纤维素为主要原料,经机械法粉碎后,室温下分别采用氢氧化钠、硫酸/丙酮、氢氧化钠/过氧化氢、氢氧化钠/过氧乙酸、氢氧化钠/乙醇溶液对其进行预处理,然后按固液比1∶50加入纤维素酶液,在一定pH值、温度、时间等条件下进行酶解,通过检测酶解液中还原糖产率来评价化学法预处理麦秸纤维素的效果。结果表明,采用氢氧化钠/过氧化氢溶液预处理麦秸纤维素的效果要略优于其它预处理溶液。     

氨预处理对大豆秸秆纤维素酶解产糖影响的研究

为了提高大豆秸秆酶解产糖能力, 以利于从大豆秸秆中提取生物降解性塑料的原料 ?? 乳酸, 对大豆秸秆纤维素预处理过程的影响因素进行了探索,对预处理前后大豆秸秆的物理结构变化、化学成分变化及预处理条件对大豆秸秆酶水解产糖的影响进行了研究。研究结果表明,粉碎结合氨处理对大豆秸秆酶水解影响较大,较适宜的预处理条件为大豆秸秆粉碎至 140 目,10%氨水处理 24h。经过预处理后大豆秸秆纤维素含量提高 70.27%, 半纤维素含量下降 41.45%, 木质素含量下降 30.16%, 有利于大豆秸秆酶解产糖。     

产氢用生物质球磨预处理工艺的优化试验

本研究采用球磨法对产氢用生物质进行预处理,以酶解后还原糖得率作为考察指标,采用电镜对粉碎后物料进行分析,并利用DPS 7.05分析软件进行试验设计和数据分析,对球磨处理工艺进行优化。分析了原料初始粒径、球料比和球磨时间对酶解糖化过程的影响,得出球料比为显著影响因素,球磨预处理最佳工艺参数为:原料初始粒径 0.45 mm,球料比20∶1,球磨时间 1 h,在此条件下,还原糖得率为 74.50%。     

产氢用生物质球磨预处理工艺的优化试验

本研究采用球磨法对产氢用生物质进行预处理,以酶解后还原糖得率作为考察指标,采用电镜对粉碎后物料进行分析,并利用DPS 7.05分析软件进行试验设计和数据分析,对球磨处理工艺进行优化。分析了原料初始粒径、球料比和球磨时间对酶解糖化过程的影响,得出球料比为显著影响因素,球磨预处理最佳工艺参数为：原料初始粒径0.45 mm,球料比20∶1,球磨时间1 h,在此条件下,还原糖得率为74.50%。     

植物基因工程对生物燃料生物质特征的改进

全球每年有多达10～50Gt的廉价植物纤维素可再生利用。美国年产40亿加仑的乙醇,大多数是以玉米为原料生产的。目前多数利用微生物产生的纤维素酶对植物纤维素进行降解预处理,去除木质素,转化为可发酵的糖,进而生产乙醇。发酵前预处理及微生物反应器产酶成本都比较高。最新的植物基因工程研究致力于改善这种状况,降低成本,利用植物自身产纤维素酶和木质素酶来降解纤维素和木质素,或者提高生物质总产量或在植株中增产纤维素。     

脂肪酶对麦秸表面自由能的影响

研究了不同条件下麦秸经Candida Cylindracea酵母产脂肪酶处理后表面自由能的变化规律。结果表明,当处理条件为:酶用量7.5kIU/g(对麦秸),温度50℃,时间8h,pH值7.5,麦秸表面自由能提高了28%左右。分析了脂肪酶处理前后麦秸外表面、麦秸正己烷抽提物的红外光谱变化,对比了脂肪酶处理前后麦秸表面的显微结构图像,结果显示,脂肪酶脱除麦秸外表面亲脂类物质层,暴露出其中的木质素和聚糖类物质,改善了水对麦秸的可及性,提高了麦秸的表面自由能。     

微波处理对纤维素产糖能力的影响

采用纤维素为原料,以离子液体为溶剂,在微波辐射下进行纤维素的预处理。预处理完成后进行再生纤维素的酶解产糖,并采用DNS分光光度计法进行还原糖产率的测定,进而分析微波功率与时间对再生纤维素还原糖产率的影响。还原糖转化率最佳值(96.21%)出现在微波功率为230W处理5min时;稻杆产糖量随着微波时间的延长而呈现先上升后下降的趋势;在较强的功率539W条件下,延长作用时间则会引起还原糖转化率的上升,但继续延长时间,溶剂完全喷溅,难以继续进行处理。     

麦秸秆开发利用的新技术

报道了利用麦秸秆生产一次性卫生餐盒、一次性卫生筷子的工艺技术,介绍了以麦秸秆为原料,通过酶解产糖并发酵制备乙醇的工艺研究。     

香菇柄酶解糖化过程的研究

对以麸皮与香菇柄为原料、绿色木霉为菌种的固态发酵产酶进行了研究.结果表明:m(麸皮)∶m(香菇柄粉)为3∶2、料水比为1∶2.0、起始pH值为5.00时,所产纤维素酶水解香菇柄的得糖率最高.在此基础上进一步设计了4因素3水平正交实验,得到最佳水解工艺条件为:底物含量5%,酶量400FPA/100mL水,pH值5.00,温度50℃.在此条件下,香菇柄的得糖率达63.2%.     

碳酸钠预处理对麦草酶水解糖化的影响

麦草是一种具有很大潜力的制取生物乙醇的可再生木质纤维素原料。文章探讨了碳酸钠预处理预浸时间、保温时间、碳酸钠用量对麦草化学成分及酶水解效率的影响。结果表明,延长碳酸钠预处理保温时间对木质素脱除无明显影响,但浆料得率和酶水解总糖转化率有所下降;合理的预浸时间为30 min,继续延长预浸时间对预处理浆料酶水解总糖转化率无促进作用;增加预处理Na2CO3用量有助于促进木质素的脱除,大部分碳水化合物保留在浆料中。在8% Na2CO3(Na2O计)用量下,麦草于80℃预浸30 min后升温至130℃,不保温所得到的浆料在纤维素酶用量为20 FPU/g(对纤维素)时,其总糖转化率为60%。     

麦秸秆的氢氧化钙预处理及酶解试验研究

采用氢氧化钙对麦秸秆进行预处理,以酶解还原糖得率为目的,分别优化预处理及酶解条件。结果表明,氢氧化钙预处理麦秸秆的最佳条件是:Ca(OH)2添加量为0.06g/g(对秸秆),固液比为1:10,在120℃下反应时间为2h;最佳酶解条件是:温度50℃,pH4.8,纤维素酶17FPU/g(对秸秆),木聚糖酶160IU/g,在添加0.15g/g(对秸秆)Tween80条件下,酶解液中还原糖质量浓度为62.32g/L,酶解还原糖得率达85.23%。     

Catalytic organosolv fractionation of willow wood and wheat straw as pretreatment for enzymatic cellulose hydrolysis

BACKGROUND: Ethanol‐based organosolv fractionation of lignocellulosic biomass is an effective pretreatment technology for enzymatic cellulose hydrolysis to produce sugars and lignin within a biorefinery. This study focuses on the catalytic effect of H₂SO₄, HCl, and MgCl₂ on organosolv pretreatment of willow wood and wheat straw. RESULTS: The use of catalysts improved fractionation of both feedstocks. The maximum enzymatic cellulose digestibility obtained was 87% for willow wood (using 0.01 mol L^?1 H₂SO₄ as catalyst) and 99% for wheat straw (0.02 mol L^?1 HCl). Non‐catalytic organosolv fractionation at identical conditions resulted in 74% (willow wood) and 44% (wheat straw) glucose yield by enzymatic hydrolysis. Application of catalysts in organosolv pretreatment was particularly effective for wheat straw. The influence of the acid catalysts was found to be primarily due to their effect on the pH of the organosolv liquor. Acid catalysts particularly promoted xylan hydrolysis. MgCl₂ was less effective than the acid catalysts, but it seemed to more selectively improve delignification of willow wood. CONCLUSION: Application of catalysts in organosolv pretreatment of willow wood and wheat straw was found to substantially improve fractionation and enzymatic digestibility. The use of catalysts can contribute to achieving maximum utilization of lignocellulosic biomass in organosolv‐based biorefineries. Copyright © 2011 Society of Chemical Industry     

一种竹腐朽菌胞外木聚糖酶的分离和特性研究

从腐朽的竹子上分离得到一株产木聚糖酶侧耳真菌Pleurotus sp.GH196,研究了其液体振荡培养的产酶条件。适宜碳源是1%稻草粉与1%麸皮组成的复合碳源,氮源是0.2%NH4NO3。经过硫酸铵分级沉淀、DEAE-Sephadex A-25离子交换层析、Sephadex G-100凝胶过滤三步纯化得到木聚糖酶的一个主要酶活组分A。该木聚糖酶在40～50℃、pH 4.0～5.5可以保持较好的稳定性,酶活最适反应条件是温度55℃、pH 4.5。     

环氧小麦秸杆纤维素球的制备及表征

以自制的小麦秸秆纤维素为原料,通过对直接活化成球环氧化和先交联后活化环氧化进行正交试验,比较了直接活化、仅交联和先交联后活化三种条件下的环氧值,得到了最佳环氧化条件。在两条制备途径各自最佳实验条件下,通过先交联后活化,可使环氧值增大到0.7074mol/100g,并制备了环氧小麦秸秆纤维素球。通过扫描电镜和红外光谱表征,证实制取的环氧小麦秸秆纤维素球具有圆球的形状和一定的孔隙结构,且环氧化后引入了环氧基官能团。     

Comparison of atmospheric aqueous glycerol and steam explosion pretreatments of wheat straw for enhanced enzymatic hydrolysis

BACKGROUND: The oversupply of cheap glycerol by the oleochemicals industry together with problems occurring in low‐boiling‐point organosolv pretreatments, has generated an interest in the use of glycerol in the organosolv pretreatment of lignocellulosic biomass. Atmospheric aqueous glycerol autocatalytic organosolv pretreatment (AAGAOP) is a promising strategy that can effectively enhance enzymatic hydrolysis of lignocellulosic biomass. As a cost‐effective technique, steam explosion pretreatment (SEP) is being adopted in industrial applications. Accordingly, work has been carried out to investigate how AAGAOP enhanced enzymatic hydrolysis of lignocellulosic biomass compares with the SEP method. RESULTS: Under controlled laboratory conditions, based on ≥ 90% cellulose recovery, AAGAOP removed ≥ 60% hemicellulose and ≥ 60% lignin from wheat straw while SEP led to ～80% hemicellulose and 10% lignin removal. Enzymatic hydrolysis yields of AAGAOP and SEP reached ～90% and ～70%, respectively. Physical‐chemical structural characterization by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT‐IR), helped explain the above results. The two methods gave priority to dissociating the guaiacyl lignin and had a relatively small effect on syringyl units. However, AAGAOP exhibited a superior performance. CONCLUSION: The two methods enhanced the enzymatic hydrolysis of lignocellulosic biomass by removing and/or altering physical‐chemical structural impediments. The AAGAOP technique, with some special advantages, was more effective than SEP in enhancing the recovery and enzymatic digestibility of cellulose. Copyright © 2008 Society of Chemical Industry     

Optimization of ozone bleaching conditions for improving wheat straw pulp quality using response surface methodology

Ozone bleaching conditions for wheat straw soda pulp were optimized using response surface methodology with central composite design. Effect of pH, consistency, and ozone dose on kappa number, brightness, and viscosity was investigated. Optimized process conditions to get minimum kappa number, maximum viscosity, and brightness were obtained as follows: pH 2.08–2.25, pulp consistency 27.4–30.0%, and ozone dose 0.4%. Validation of the model predicted values and experimental values obtained for optimum conditions has the difference of 0.5–2.0%, which shows that the developed model for ozone bleaching of wheat straw pulp is satisfactory.     

污泥与生物质共热解制备生物质炭工艺优化及吸附性能

通过污泥与秸秆（玉米秸秆、水稻秸秆、小麦秸秆、芝麻秸秆）慢速共热解的方法,在不同热解温度（300℃、400℃、500℃、600℃）、热解时间（0.5h、1h、1.5h、2h）及配比（污泥与生物质1∶0、1∶0.5、1∶1、1∶2）条件下制备4种生物质炭,即SCBC（污泥-玉米秸秆生物质炭）、SRBC（污泥-水稻秸秆生物质炭）、SWBC（污泥-小麦生物质炭）、SSBC（污泥-芝麻生物质炭）,研究了不同热解条件对生物质炭产率、pH、元素组成、表面特征、吸附性能的影响,并根据吸附性能筛选出各生物质炭的最优制备工艺。结果表明,热解温度为500℃、热解时间为2h、污泥与玉米秸秆、芝麻秸秆配比为1∶1时,污泥与水稻秸秆、小麦秸秆配比为1∶2时,制备的生物质炭吸附性能最优。最优制备工艺条件下,4种生物质炭吸附性能相比：SWBC > SRBC > SCBC > SSBC。     

A comprehensive ligninolytic pre-treatment approach from lignocellulose green biotechnology to produce bio-ethanol

In the present study, we developed a novel ligninolytic enzymes based pre-treatment method for lignocellulosic wheat straw to depolymerize lignin and expose the cellulose polymers to produce bio-ethanol. Wheat straw was pre-treated with ligninolytic enzymes extract produced from Ganoderma lucidum under optimum solid state fermentation conditions. The pre-treated biomass was further subjected to the enzymatic hydrolysis by the crude unprocessed cellulases (β-1,4 endoglucanase, 53.5 ± 1.24 U/mL; β-1,4 exoglucanase, 41.3 ± 1.31 U/mL; β-1,4 glucosidase, 46.8 ± 1.43 U/mL; and xylanase 39 ± 2.2 U/mL) produced by Trichoderma harzaianum. Under optimal conditions for enzymatic saccharification, 10% (w/v) of pre-treated biomass was hydrolyzed completely and converted to 72.5 and 2.4 g/L of glucose and xylose, respectively. Initial time screening Sequential Saccharification and Fermentation (SSF) of the concentrated enzymatic hydrolyzate (10%, w/v) by Saccharomyces cerevisiae produced 22.6 g/L ethanol in a fermented medium after 72 h of temperature controlled incubation at 37 °C. For maximum ethanol production, different physical and nutritional parameters like pH, temperature, substrate level and inoculum sizes were optimized. Under optimal conditions ethanol production of 33.5 g/L was obtained from ligninolytic treated residual (wheat straw) biomass.