表面活性剂对木薯秆酶水解的影响

采用纤维素酶促水解的方法,以木薯秆为底物,研究了5种表面活性剂(SDS、Tween 20、Tween 80、Triton x-100、Triton x-114)及其用量对木薯秆酶水解得率的影响。结果表明,除SDS外,其他4种表面活性剂对木薯秆酶水解有不同程度的促进作用,Tween 20的效果最为显著。添加2.5 g/L的Tween 20水解72 h和5.0 g/L的Triton x-114水解60 h,酶水解得率分别达到了49.23%、49.48%,比空白样提高了33.45%和34.13%。     

离子及表面活性剂对甜高粱秆渣酶解的影响

为了提高纤维素酶水解经高温液态水处理后的甜高粱秆渣的效率,探讨了多种阴离子、阳离子以及吐温80(Tween 80)对纤维素酶活力的影响,并初步探讨了Tween 80影响甜高粱秆渣酶解的机制。酶激活试验表明,Br^-、I^-、NO₃^-、Ca²⁺、Mg²⁺和Co²⁺对纤维素酶有激活作用,但对甜高粱秆渣的水解效率提高不明显。添加Tween 80发现,随着浓度的增加,它对纤维素酶的抑制作用增强,而Tween 80添加量为0.175 ml·(g甜高粱秆渣)^-1时,甜高粱秆渣的酶解效率由16.6%提高到37.9%。吸附试验表明,甜高粱秆渣对纤维素酶和Tween 80的吸附达到一定限度后不再上升,Tween 80能显著降低甜高粱秆渣对纤维素酶的吸附。红外光谱分析发现,木质素对Tween 80的吸附要强于它对纤维素酶的吸附。     

小球藻在蔗渣酶解液中的异养生长及其脂肪酸生成

在高温液态水处理的甘蔗渣酶解过程中添加Tween80可使聚糖转化率提高11.4%。根据蔗渣酶解液中糖的种类及含量,用葡萄糖、木糖和纤维二糖标准品模拟蔗渣酶解液组成配制成相应的混合糖培养基,同时配制仅含葡萄糖的培养基,在有、无Tween80和BG11(Blue-Green 11)的条件下,考察小球藻在不同培养基中的异养生长及脂肪酸生成。结果显示Tween80对小球藻的生长具有抑制作用,纤维二糖也会影响小球藻的生长;小球藻在添加BG11的葡萄糖培养基中的生物量最高,为1.97 g·L^-1,在添加BG11的蔗渣酶解液中的生物量高出未添加BG11的2倍,在含有Tween80和BG11的蔗渣酶解液中的总脂肪酸含量最高,达到6.90%,在所有培养基中产生的脂肪酸以C_16:0、C_18:1、C_18:3、C_20:1和C_20:4为主;培养基组成优化可进一步提高微藻生物量和油脂产量。     

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%。     

假交替单胞菌JMUZ2重组κ-卡拉胶酶的异源表达和酶学性质

将假交替单胞菌JMUZ2的κ-卡拉胶酶基因在大肠杆菌中异源表达,利用亲和层析对重组κ-卡拉胶酶进行分离纯化,表征重组酶的酶学性质,利用质谱分析κ-卡拉胶的酶解产物,并进行产物的抗氧化活性分析。结果表明,假交替单胞菌JMUZ2的κ-卡拉胶酶属于GH16家族,能专一性降解κ-卡拉胶,重组κ-卡拉胶酶的最适反应温度和pH分别为50℃和8.0,在40℃条件下处理1 h,保持约80%残余活力。重组酶对去垢剂Tween 20、Tween 80和Triton X-100有良好的耐受性。LC-MS分析显示,重组酶水解κ-卡拉胶的终产物为二糖和四糖。酶解产物对·OH自由基、DPPH自由基、ABTS自由基具有一定清除作用,还具有良好的还原能力。重组κ-卡拉胶酶的酶学性质及酶解产物的分析为该酶用于κ-卡拉胶寡糖绿色制备的应用奠定理论基础。     

竹浆分批加酶工艺对长时间纤维素酶解性能的影响

优化纤维素酶水解工艺对于纤维素的高效利用具有重要意义。实验在保证纤维素酶相同的添加量时,采用多种方式分批添加纤维素酶水解竹浆,在长时间(7 d)的酶解过程中测定每天还原性糖产量,最后对长时间酶解过程中的影响因素进行了探究。实验结果表明:采用(0.35 mL+0.15 mL+0.1mL)添加工艺提高了酶解效率,酶解7d后糖产量提高了4.36%;纤维素酶随着培育时间的进行活性不断减小,培育1 d后的酶活性仅为原酶活性的53.87%;酶解糖产量随葡萄糖浓度的增加而降低,当葡萄糖浓度为30 mg/mL时,糖产量较无葡萄糖实验组降低了30.7%。酶解过程中酶活的丧失以及底物的抑制可能是影响纤维素酶长时间水解过程中的重要因素。     

碳源对平菇选择性降解稻草木素及其后续酶解性能的影响

前期研究发现,平菇预处理稻草表现出比较好的脱木素选择性和纤维素酶水解效果。为了使预处理后的稻草在纤维素酶水解过程中得到更多的单糖,通过向平菇预处理稻草固体培养基中添加麸皮、玉米皮和木聚糖,研究外加碳源对平菇降解稻草木素的选择性及后续酶水解效果的影响。结果表明,添加适量的麸皮和木聚糖可提高平菇处理稻草的脱木素选择性。麸皮和木聚糖添加量为稻草粉的10%时,脱木素选择系数分别由对照的1.86增加至2.58和2.03;预处理样品酶解后原料中总糖的46.8%和45.9%转化为可发酵单糖,分别比对照的35.5%提高了30%和28%。添加玉米皮对平菇预处理酶解效果影响相对较小,添加量为5%时,预处理样品酶解后总糖转化率仅比对照提高15%,增加添加量酶解总糖转化率反而低于对照样品。     

杨木屑硫酸水解的研究

对杨木屑分别进行浓硫酸和稀硫酸水解,稀硫酸水解时水解温度为200℃,硫酸质量分数为2.5%时,得糖率最高为64.5%;浓硫酸水解时水解温度为60℃,硫酸质量分数为70%,得糖率可达到96.4%。采用低酸固比硫酸水解杨木屑,考察水解温度、时间及二次水解时间对得糖率的影响,结果表明:较好的条件是水解温度95℃,时间0.5h,二次水解时间2h,得糖率可达到61.9%。此方法与浓硫酸、稀硫酸水解相比较,耗酸量少,反应条件较温和,能取得较好的水解效果。     

纤维素酶高效水解麦秆的工艺研究

以纤维素酶水解蒸汽爆破麦秆的过程为研究对象,考察了底物浓度、纤维素酶用量、β-葡萄糖苷酶装载量以及化学激活剂对麦秆水解的影响。结果表明,高底物浓度下的最佳酶解工艺条件为底物(麦秆)浓度20%,酶装载量(U/g纤维素):滤纸酶活45、β-葡萄糖苷酶25、木聚糖酶800,0.1 mmol/L Mg2+、0.1 mmol/L Co2+、10 mmol/L Fe3+,1 g/L PEG2000、1 g/L Tween80和1 g/L山梨醇,搅拌速度120~150 r/min,分批补料,p H4.8,50℃,水解时间144 h。在此条件下,还原糖浓度达115.43 g/L,葡萄糖浓度达88.39 g/L,转化率也分别达到78.04%和88.73%。     

三氟乙酸/超声波预处理对芒草纤维素结构及酶解效果的影响

以芒草秸杆为原料,通过三氟乙酸/超声波对其进行预处理,研究预处理前后芒草秸杆酶解效果。采用DNS法测定处理样品中还原糖含量;通过红外光谱及XRD分析考察预处理对芒草秸杆成分及纤维组织结构的影响。结果表明,三氟乙酸/超声波能有效破坏纤维素的晶形结构,增加纤维素酶与底物的酶解可及度,促进了芒草秸杆的酶解糖化。在40%三氟乙酸溶液、30℃、固液比为1∶30及超声波的辅助作用下预处理4h的芒草秸杆,当p H为4.6,加酶量22mg·g^-1,45℃酶解72h,其酶解糖化率可达64.6%。     

Tween 80强化-活化过硫酸钠氧化修复多环芳烃污染土壤

考察了在典型非离子表面活性剂Tween 80辅助增溶作用下,活化过硫酸钠（SPS）对多环芳烃（PAHs）污染土壤的氧化修复性能。研究结果表明,室温下10%（20 g·L^-1）的Tween 80对PAHs的平均洗脱效率达到37.8%,连续淋洗样品4次,PAHs平均解吸率可达89.5%以上。当使用柠檬酸（CA）络合硫酸亚铁为活化剂时,在84 mmol·L^-1 SPS浓度条件下,将反应Fe （Ⅱ）浓度由0.84 mmol·L^-1增加至4.2 mmol·L^-1,PAHs的平均去除率可从64.3%提高至73.5%。但当Fe （Ⅱ）浓度继续增大时,PAHs的去除率反而降低。固定SPS与Fe （Ⅱ）摩尔比为20：1,当SPS浓度持续增加至168 mmol·L^-1时,总PAHs的平均去除率可提高到86.1%,之后SPS浓度对PAHs的去除率无显著影响。在活化SPS体系中添加0.25%的Tween 80后,与不加Tween 80的反应系统相比,PAHs平均去除率提高约14%。最终优化结果显示,在0.25% Tween80,42 mmol·L^-1 SPS,2.1 mmol·L^-1 Fe （Ⅱ）浓度条件下,受污染土壤中PAHs平均去除率可达到90.0%。因此,Tween 80强化过硫酸钠可作为PAHs污染场地氧化修复的有效手段。     

表面活性剂与离子液体对β-葡萄糖苷酶的协同影响

为考察表面活性剂和离子液体1-乙基-3-甲基咪唑磷酸二乙酯盐（[EMIM]DEP）对类芽孢杆菌sp. LLZ1 β-葡萄糖苷酶活性的影响,在酶活测定体系中加入一定浓度的表面活性剂和[EMIM]DEP。结果表明：添加5%的[EMIM]DEP使β-葡萄糖苷酶的活性增强了12.00%,进一步添加0.1%鼠李糖脂、Span20、PEG4000和Tween80分别使酶活增强了21.85%、12.07%、8.57%和5.25%,而Triton X-100和SDS分别使酶活降低了4.59%和10.63%。动力学曲线和动力学参数表明随着表面活性剂和5%[EMIM]DEP对β-葡萄糖苷酶活性的增强,米氏常数K_m随之减小。圆二色谱（CD）分析表明分别经0.1%鼠李糖脂、Span20、PEG4000和Tween80处理后,β-葡萄糖苷酶的α-螺旋分别增加1.00%、0.78%、0.72%和0.80%,添加SDS导致α-螺旋减少5.72%。荧光光谱表明同时添加表面活性剂和5%[EMIM]DEP改变了β-葡萄糖苷酶的最大发射波长。差示扫描量热法(DSC)表明0.1%鼠李糖脂和5%[EMIM]DEP提高了β-葡萄糖苷酶的中点温度和平均展开焓。使用0.1%鼠李糖脂协同5%[EMIM]DEP水解纤维二糖,转化率提高了21.93%。     

高内相乳液法制备聚丙烯酰胺多孔水凝胶及应用

以亲水性二氧化硅纳米粒子（N20）和乳化剂Tween80为复合稳定剂,环己烷为油相制备高内相乳液,再以此乳液为模板制备聚丙酰胺（PAM）多孔水凝胶。乳液光学显微镜照片及PAM多孔水凝胶SEM照片表明N20用量及Tween80用量对材料孔径形貌及直径有直接影响;压汞仪数据表明当N20用量为3%、Tween80用量为9%时,多孔水凝胶平均孔径为38.06nm,孔隙率为77.54%,20h饱和吸水率可达402g/g;吸附实验表明PAM多孔水凝胶对Mn(Ⅱ)具有良好的吸附性能,吸附过程符合准二级动力学方程,属于化学吸附,当溶液pH为4时,120min可达吸附饱和,吸附量为474.64mg/g。     

Destabilization of Emulsion Formed During Aqueous Extraction of Peanut Oil: Synergistic Effect of Tween 20 and pH

To destabilize the emulsion formed during aqueous extraction processing (AEP) of peanuts, Tween and Span series surfactants (Tween 20, Tween 80, Span 20, and Span 80) were used alone or in combination to break the emulsion. Results indicate that only Tween surfactants had a pronounced demulsifying effect that was dependent on Tween concentration and system pH. When 1.2 wt% Tween 20 aqueous solution was used for oil extraction at pH 10.0, the highest free oil yield was achieved at 76.1 %, which was similar to the oil recovery of using proteases as a destabilization agent. The results obtained using a model emulsion system containing peanut oil and Tween 20/peanut protein isolates (PPI) showed that when Tween 20 and PPI coexisted in extraction medium at pH 10.0, the dynamic interfacial tension and droplet size distribution curves were very similar to those when Tween 20 was used alone, suggesting that Tween 20 dominated at the interface, instead of PPI. Destabilization of the model emulsions relied on three important factors: inclusion of Tween 20 at the initial mixing stage, high pH, and a gentle mixing speed. A synergistic destabilization mechanism of using Tween 20 at high pH during AEP was proposed. The discovery of Tween 20 as an effective demulsifier significantly contributes to the development of AEP of oilseeds.     

Oxidation and Colloidal Stability of Oil-in-Water Emulsion as Affected by Pigmented Rice Hull Extracts

Extracts from the hull of pigmented rice were prepared using a mixture of methanol–water (1:1, 2:1, and 3:1, v/v) for different extraction times (0–180 min). Total phenolic content (TPC) of the extracts increased with increasing concentration of methanol and extraction time (P < 0.05). A positive correlation between TPC and antioxidant activities, i.e., DPPH and ABTS radical scavenging activities and reducing power, was observed. The extracts prepared using methanol–water at the ratio of 3:1 for 180 min at 50 °C, referred as rice hull phenolic extract (RHPE), showed the highest TPC and free radical scavenging abilities and reducing power (P < 0.05). When the effects of RHPE on physicochemical stability of the emulsions stabilized by different emulsifiers, i.e., Tween 20 and bovine serum albumin (BSA), were examined, the collapse of emulsion was retarded when RHPE was applied in BSA‐based emulsions, whereas a negative effect was noticeable in Tween 20‐based counterpart. Lower oxidative degree was found for BSA stabilized emulsions, compared to Tween 20 containing system. RHPE (1–3 %) markedly improved the oxidative stability, particularly for BSA stabilized emulsions. Therefore, RHPE could be employed along with the selected protein to increase physicochemical stability of emulsion.     

Controllable preparation,rheology, and plugging property of micron‐grade polyacrylamide microspheres as a novel profile control and flooding agent

A series of micron‐grade polyacrylamide microspheres were prepared by inverse suspension polymerization of acrylamide (AM) and N,N′‐methylene bisacrylamide (MBA) in oil phase, with Span80 and Tween80 as dispersion stabilizers, and ammonium persulfate (APS) as an initiator. The conversion rate and coagulum rate were introduced to optimize the inverse suspension polymerization conditions of micron‐grade polyacrylamide microspheres. The swelling property of polyacrylamide microspheres in aqueous solution and the rheology of polyacrylamide microspheres suspension were characterized. The matching factor was introduced to characterize the matching relationship between the particle size of polyacrylamide microspheres and pore‐throat size of reservoirs. The optimized synthesis results show that the conversion rate is high, and the coagulum rate is low when the mass ratio of Span80 to Tween80 is 3 : 1. The particle size of the polyacrylamide microspheres is controlled by varying the concentration of dispersion stabilizer. The polyacrylamide microspheres show an obvious swelling property, which depends on the concentration of NaCl and temperature. The polyacrylamide microspheres suspension shows different rheological properties at different temperature and shear rate. When the temperature is low, it behaves as pseudoplastic fluid, dilatant fluid and quasi‐newtonian fluid in turn with the increase of shear rate. When the temperature is high, it behaves as dilatant fluid and quasi‐newtonian fluid in turn with the increase of shear rate. The micron‐grade polyacrylamide microspheres prefer to plug sand pack with optimal matching factor. When the matching factor is 1.35–1.55, the polyacrylamide microspheres can be transported into the deep area of sand pack, and the ultimate plugging rate is more than 85%, which indicates that the matching factor is an effective parameter to evaluate the matching relationship between polyacrylamide microspheres and reservoirs. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1124‐1130, 2013