辐射聚合离子性水凝胶固定化酵母细胞

在低温(-78℃)下,通过辐照使2-丙烯酰胺2-甲基丙磺酸(TBAS)和聚乙二醇二甲基丙烯酸醇系列单体聚合,获得了具有离子性的水凝胶载体。用这些载体固定化酵母细胞的乙醇生产力均比游离细胞高,其中用poly TBAS-14G固定化细胞的乙醇生产力是游离细胞的4.5倍,每小时糖的转化率达50％。固定化酵母的活性随聚乙二醇二甲基丙烯酸分子中乙二醇数目的增加而增加。固定化酵母具有较高活性的原因是这些高分子载体具有一定的多孔性、膨胀性,载体带有电荷并具有一定的机械强度,固定化细胞能较好地繁殖,使载体内具有较高的细胞密度。     

Immobilization of yeast cells with ionic hydrogel carriers by adhesion-multiplication

The mixture of an ionic monomer, 2-acrylamido 2-methylpropanesulfonic acid (TBAS), and a series of poly(ethylene glycol) dimethacrylate (nG) monomers were copolymerized with 60Co gamma-rays, and the produced ionic hydrogel polymers were used for immobilization of yeast cells. The cells were adhered onto the surface of the hydrogel polymers and intruded into the interior of the polymers with growing. The immobilized yeast cells with these hydrogel polymers had higher ethanol productivity than that of free cells. The yield of ethanol with poly(TBAS-14G) carrier was the highest and increased by 3.5 times compared to the free cells. It was found that the ethanol yield increased with the increase of glycol number in poly(ethylene glycol) dimethacrylate. The state of the immobilized cells was observed with microscope, and it was also found that the difference in the ethanol productivity is mainly due to the difference in the internal structure and properties of polymer carrier, such as surface charge, hydrophilicity, and swelling ability of polymer carrier.     

辐射技术制备固定化蛋白酶

本文探讨了在低温条件下,~(60)Co-γ射线诱导亲水性单体丙烯酸羟乙酯、疏水性的聚乙二醇二甲基丙烯酸酯系列单体聚合固定化蛋白酶的方法,研究了单体的分子结构,单体性质对固定化蛋白酶活性和热稳定性的影响。实验结果表明,采用单官能团单体(HEA)制备的固定化蛋白酶相对活性高于双官能团单体,固定化酶相对活性随疏水性单体聚乙二醇二甲基丙烯酸酯中乙二醇数的增加而增加。对于亲水性单体HEA固定化蛋白酶的相对活性则随单体的冷却速率的增加而增加。固定化蛋白酶的热稳定性随单体的亲水性而变化。     

吸附法固定化绿色木霉(Trichoderma reesei)生长细胞

本文应用辐射技术,在纸表面复盖不同性质的高分子,以此作为固定化生长细胞的载体,吸附绿色木霉细胞,并测定了固定化绿色木霉细胞的纤维素酶活性。当纸复盖有3种亲水性均聚体poly-HEA、poly-HEMA,poly-HPMA和一种疏水性均聚体poly-A4G时,细胞被吸附在这4种载体上,并能产生纤维素酶,但是只有复盖poly-HPMA的载体固定化细胞的纤维素酶活性(FPA)高于游离细胞。当纸复盖不同组成的HEA-A-TMPT、HEMA-A-TMPT.HPMA-A-TMPT和A4G-A-TMPT的共聚体时,用这些载体固定化细胞的FPA均比复盖均聚体的增加。用复盖不同组成的poly(HPMA-A-TMPT)载体固定化细胞,其FPA均比游离细胞增加,最高的增加了60％。用复盖有50％:50％和75％:25％的poly(HEA-A-TMPT)共聚体载体固定化细胞,其FPA分别比游离细胞增加了70％和60％。FPA增加是由于吸附的细胞重量增加,而固定化细胞的重量与复盖于纸上的高分子的性质(例如含水量)有关,复盖的高分子含水量10％左右时,固定化细胞重量最高,在载体表面复盖适宜的高分子有利于细胞的吸附和生长。     

固定化酵母粒子强化及其对甜高粱茎秆汁液乙醇发酵的影响

采用正交试验设计开展了三亚乙基四胺(TTA)和戊二醛(GLU)的浓度和处理时间对海藻酸钙固定化酵母粒子的化学强度影响的试验研究，并以甜高粱茎秆汁液为原料，在5 L的反应器中进行乙醇发酵试验，考察强化后的固定化酵母粒子对乙醇发酵的影响。结果表明，最优的固定酵母粒子强化处理的方案为：TTA浓度为0.5%，处理时间为120 min；GLU浓度为0.5%，处理时间为8 min。连续8批次的甜高粱茎秆汁液乙醇发酵试验结果表明，最优组合强化后固定化酵母粒子用于乙醇发酵时，平均乙醇得率和变异系数(CV%)分别为84.78%和8.08%，而未强化的固定化酵母籽子为84.32%和9.68%，可见，最优组合强化后的固定化酵母粒子的发酵性能略优于未强化的固定化酵母籽子。该文为固定化酵母发酵甜高粱茎秆汁液制取生物乙醇技术的研究提供了参考。     

固定化酵母粒子强化及其对甜高梁茎秆汁液乙醇发酵的影响

采用正交试验设计开展了三亚乙基四胺(TTA)和戊二醛(GLU)的浓度和处理时间对海藻酸钙固定化酵母粒子的化学强度影响的试验研究,并以甜高粱茎秆汁液为原料,在5 L的反应器中进行乙醇发酵试验,考察强化后的固定化酵母粒子对乙醇发酵的影响.结果表明,最优的固定酵母粒子强化处理的方案为TTA浓度为0.5%,处理时间为120 min;GLU浓度为0.5%,处理时间为8 min.连续8批次的甜高粱茎秆汁液乙醇发酵试验结果表明,最优组合强化后固定化酵母粒子用于乙醇发酵时,平均乙醇得率和变异系数(CV%)分别为84.78%和8.08%,而未强化的固定化酵母籽子为84.32%和9.68%,可见,最优组合强化后的固定化酵母粒子的发酵性能略优于未强化的固定化酵母籽子.该文为固定化酵母发酵甜高粱茎秆汁液制取生物乙醇技术的研究提供了参考.     

Red wine making by immobilized cells and influence on volatile composition

Red wine making using yeast cells immobilized in two types of raisin berries, at various temperatures (6-30 degrees C), was studied. A modification of the batch bioreactor was used to separate the grape skins used for color extraction from the biocatalyst and the fermenting grape must. The evaluation of the immobilized biocatalysts was made on terms of productivity and organoleptic quality, including color intensity and formation of volatiles. The immobilized cells were found capable of low-temperature wine making, producing red wines containing more than 11% v/v alcohol in 8 days at 6 degrees C. The quality of wines was examined by gas chromatography (GC) and GC-MS analysis and sensory evaluation. Higher alcohol concentrations were decreased, and ethyl acetate concentrations increased by the drop of temperature. Many esters, alcohols, carbonyls, and miscellaneous compounds were identified in wines produced by immobilized cells, revealing no significant qualitative differences as compared to wines produced by free cells. The sensory evaluation showed that the best red wine was produced at 6 degrees C.     

用基因组改组技术改良发酵木糖酵母Candida tropicalis XY-19的耐乙醇性能

Candida tropicalis XY-19是一株具有优良乙醇发酵性能的发酵木糖酵母,其发酵葡萄糖产乙醇性能与目前酒精工业生产菌种--安琪酒精酵母相近,但XY-19的耐乙醇性能远比安琪酒精酵母差,XY-19在含有超过7%（v/v）乙醇的培养基中不能生长。以XY-19为出发菌株,经紫外线诱变获得了5株能在7.5%（v/v）乙醇的培养基中旺盛生长的突变株,经Co-60诱变获得了8株能在含8%（v/v）乙醇的培养基中旺盛生长的突变株。然后,以紫外线诱变得到的5株菌和Co-60诱变得到的8株菌及耐乙醇性能较好的酿酒酵母（S.cerevisae Angel,S.cerevisae4608和S.cerevisae172）为出发菌株,经过4轮Genome shuffling结合木糖乙醇梯度平板的筛选,获得了4株（G3-13,G3-18,G3-57和G3-60）能够在12%乙醇平板上生长的菌株,其乙醇耐受性比野生菌株XY-19提高了71%,为将XY-19进一步开发成纤维质乙醇发酵的生产菌种奠定基础。本研究结果进一步体现了Genome shuffling技术在改良如乙醇耐受性等多基因控制性状上的突出优势,为工业生产菌种的快速有效改良提供了一种有效的方法。     

甜高粱茎秆液态发酵制取乙醇工艺技术

甜高粱茎秆液态发酵制取乙醇工艺技术是国家高技术研究发展计划(863计划)《甜高粱茎秆制取乙醇》(课题编号:2001AA 514040)项目中关键技术之一,本文简要的论述了该项技术的工艺流程、工作原理和性能指标。该项研究成果主要以甜高粱茎秆汁液为原料,采用固定化酵母流化床快速发酵工艺,并克服了固定化细胞技术中普遍存在的载体机械强度低、使用寿命短等技术难题,同时根据乙醇酵母的生理、生化特性制定了一套适用于高技术的乙醇生产新工艺。该项技术具有发酵速度快、发酵率高,成熟醪酒份高、残糖低、能耗低。     

Malolactic fermentation in wine with Lactobacillus casei cells immobilized on Delignified cellulosic material

In this work Lactobacillus casei ATCC 393 cells immobilized on delignified cellulosic material (DCM) were used for malolactic fermentation (MLF) of wine. Wine was produced using yeast cells immobilized on DCM at 20 degrees C, and after alcoholic fermentation, MLF at 27 degrees C followed using immobilized L. casei ATCC 393 cells. A total of 11 repeated alcoholic and subsequent MLF batches were performed within a period of 1 month. As the repeated MLF batches proceeded, the MLF activity of the immobilized biocatalyst was reduced. Malic acid degradation was reduced from 80 to 2%, pH was reduced by 0.5-0.1 unit, acetic acid concentrations were slightly reduced or remained stable (0.002 g/L), the higher alcohols 1-propanol, isobutyl alcohol, and amyl alcohol were decreased by 84, 23, and 11%, respectively, and ethyl acetate concentration was increased by approximately 56%. Wine samples were analyzed by GC-MS before and after MLF, revealing some qualitative differences.     

Whey liquid waste of the dairy industry as raw material for potable alcohol production by kefir granules

Kefir granular biomass was used in the fermentation of sweet whey and proved to be more effective compared to single-cell biomass of kefir yeast. The operational stability of the biocatalyst was assessed by carrying out 20 repeated batch fermentations. Levels of ethanol productivity reached 2.57 g L(-1) h(-1)), whereas the yield was 0.45 g/g. The fermentation time was only 8 h. Mixtures of sweet whey with molasses were fermented at initial densities ranging from 4.2 to 10.2 degrees Be and resulted in ethanol yield factors between 0.36 and 0.48 g of ethanol/g of utilized sugar. Lower degrees Be values led to an increase of percentages of ethyl acetate on total volatiles determined and a reduction of amyl alcohols. The addition of 1% black raisin extract to whey appears to promote whey fermentation, whereas the same was not observed in the case of white sultana extract addition. It was finally established that it is preferable to ferment mixtures of whey-molasses by adding molasses in whey after the completion of whey fermentation.     

Continuous whey fermentation using kefir yeast immobilized on delignified cellulosic material

Delignified cellulosic-supported biocatalyst, prepared by immobilization of kefir yeast on delignified cellulosic material (DCM), was found to be suitable for continuous, modified whey fermentation. The modified whey contained 1% raisin extract and molasses. Ethanol productivities ranged from 3.6 to 8.3 g L(-1)day(-1), whereas parameters such as ethanol concentration, residual sugars, and daily fermented whey productivity were acceptable for the production of potable alcohol and alcoholic drinks in industrial fermentations. The continuous fermentation bioreactor was operated for 39 days, stored for 18 days at 4 degrees C, and operated again for another 15 days without any diminution of the ethanol productivity. The concentrations of higher alcohols (propanol-1, isobutyl alcohol, and amyl alcohols) were low. The main volatile byproducts formed in the continuous process were similar to those observed in alcoholic beverages, and the fermented whey had a good aroma. The concentrations of higher alcohols were very low when compared to that of ethyl acetate, therefore resulting in a quality product. The possibility of using such a process for the production of potable alcohol or a novel, low-alcohol content drink is proposed.     

云母粉聚丙稀酸交联物的保水特征及其对土壤供钾状况的影响

选用云母粉和丙烯酸单体为原料,通过交联合成方式,合成了一种新型的保(吸)水材料,在探讨了其保水特征的基础上,采用室内培养试验,进一步分析了其对土壤供钾状况的影响.结果表明,云母粉聚丙烯酸交联物具有很好的保(吸)水特性,尤其具有很好的吸含盐溶液的能力;将其施入土壤后在低剂量时就可以明显提高土壤的供钾强度,并在高剂量时提高土壤钾素的缓冲容量.     

Characterization of Miscanthus giganteus Lignin Isolated by Ethanol Organosolv Process under Reflux Condition

Miscanthus giganteus lignin was extracted by an organosolv process under reflux conditions (4 h) with varying concentrations of ethanol (65%, 75%, 85%, 95%) and 0.2 M hydrochloric acid as catalyst. The resulting lignin was extensively characterized by size exclusion chromatography (SEC), Fourier-transform infrared spectroscopy (FTIR), gas chromatography-mass spectrometry (GC/MS), two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR), and chemical analysis (residual sugars, Klason lignin, ash). The predominant linkage units present were β-O-4' (82-84%), resinol (6-7%), and phenylcoumaran (10-11%). The 65% ethanol solvent system gave the lowest lignin yield (14% of starting biomass) compared to 29-32% of the other systems. Increasing ethanol concentration resulted in decreasing carbohydrate content of the lignins (3.6-1.1%), a higher solubility in tetrahydrofuran (THF), a slight reduction of the molecular weight (M(w) 2.72-2.25 KDa), an increasing α-ethoxylation, and an increase in ethoxylated phenylpropenoic compounds (p-coumaric and ferulic acid), but the S/G ratio of the monolignols (0.63, GC/MS) and Klason lignin content (86-88%) were unaffected. An extraction method for these ethyl-esterified phenylpropenoids and smaller molecular weight lignin compounds was developed. The effect of reaction time (2, 4, and 8 h) was investigated for the 95% ethanol solvent system. Besides increased lignin yield (13-43%), a slight increase in M(w) (2.21-2.38 kDa) and S/G ratio (0.53-0.68, GC-MS) was observed. Consecutive extractions suggested that these changes were not from lignin modifications (e.g., condensations) but rather from extraction of lignin of different composition. The results were compared to similar solvent systems with 95% acetone and 95% dioxane.     

Preparation of molecularly imprinted polymers using anacardic acid monomers derived from cashew nut shell liquid

The objective of this work was to use monomers from cashew ( Anacardium occidentale L.) nut shells to develop molecularly imprinted polymers. Cashew nut shell liquid (CNSL) is a cheap and renewable agro byproduct consisting of versatile monomers. Solvent-extracted CNSL contains over 80% anacardic acid (AnAc) with more than 90% degree of unsaturation in its C 15 side chain. From AnAc monomer, anacardanyl acrylate (AnAcr) and anacardanyl methacrylate (AnMcr) monomers were synthesized and their chemical structures were characterized by Fourier transform IR and NMR. Different imprinted bulk polymers based on AnAc, AnAcr, and AnMcr functional monomers have been prepared. In the present study, each functional monomer was separately copolymerized in toluene with ethylene glycol dimethacrylate and divinylbenzene as cross-linkers, using racemic propranolol as a model template. While the AnAc based polymer revealed a meager rebinding ability, the imprinted polymers made from AnAcr and AnMcr displayed highly specific propranolol binding. At a polymer concentration of 2 mg/mL, AnAcr and AnMcr based imprinted polymers were able to bind over 50% of trace propranolol (initial concentration 1.2 nM). Under the same condition propranolol uptake by the two nonimprinted control polymers was less than 20%. Chiral recognition properties of these polymers were further confirmed using tritium-labeled (S)-propranolol as a tracer in displacement experiments, suggesting that the apparent affinity of the imprinted chiral sites for the correct enantiomer is at least 10 times that of the mismatched (R)-propranolol. Moreover, cross reactivity studies of these polymers showed that the (S)-imprinted sites have higher cross-reactivity toward (R, S)-metoprolol than (R)-propranolol and (R)-timolol.     

晋西黄土区苹果 + 大豆间作系统小气候及其对作物生产力的影响

为了评价果农间作系统的生态效益和经济效益,指导果农间作系统的物种选择和行间配置等农艺措施的生产实践,以晋西黄土区山西省吉县3年生苹果＋大豆间作系统（T1）、5年生苹果＋大豆间作系统（T2）、7年生苹果＋大豆间作系统（T3）和大豆单作系统（CK）为对比试验材料,通过布设根障,在分析苹果＋大豆间作系统小气候各因子特征的基础上,利用灰色关联法,研究不同树龄间作系统的小气候综合效应,并评价小气候对作物生产力的影响.结果表明：1）与大豆单作系统相比,苹果＋大豆间作系统光合有效辐射强度降低了30.3％ ～ 59.0％,气温下降了5.9％～17.9％,表层土壤温度下降了14.6％～42.7％,空气相对湿度增加了7.0％ ～ 17.9％;2）随着树龄的增加,苹果＋大豆间作系统对大豆单作系统的小气候关联系数逐渐降低,其中,小气候各因子中,空气相对湿度和光合有效辐射强度与大豆单作系统的关联度最小;3）各树龄苹果＋大豆间作系统的大豆根茎叶生物量和产量均低于大豆单作系统.树龄越大,苹果＋大豆间作系统的光拦截作用和降温增湿作用越明显,小气候综合效应也越强,但各树龄苹果＋大豆间作系统的小气候均会对间作大豆生产力水平产生负面效应.     

里氏木霉Trichoderma reesei固定化细胞酶液水解辐射预处理稻麦秸秆的研究

用1×10~5、3×10~5、5×10~5和10×10~5 Gy的电子束和电子束加4％NaOH复合预处理稻麦秸秆。预处理稻秆200目以上粉末随辐照剂量的增加而增中。用1％纤维素酶水解电子束预处理稻麦秸秆48小时,葡萄糖得率随辐照剂量的增加而增加,10×10~5 Gy照射的比未预处理的增加了70％—80％;而复合预处理稻麦秸秆的葡萄糖得率在5×10~5 Gy以内,随辐射剂量增加而增加,分别为36％和35％,比未处理的10.2％增加了约2.5倍,而用10×10~5 Gy的反而下降。通过辐射聚合在纱布表面覆盖高分子poly(HEA)、poly(HEMA)、poly(HPMA)、poly(A-4G)和poly(A-TMPT),并以此作为固定化里氏木霉细胞的载体。这些载体均能较好地固定化里氏木霉细胞,固定化细胞的滤纸活性(FPA)均高于游离细胞,其中覆盖poly(HPMA)的载体固定化细胞的效果最好,FPA为3.5U/ml,比游离细胞增加了近40％。用这些固定化细胞的酶液水解NaOH和电子束复合预处理的稻麦秸秆,其葡萄糖得率随辐照剂量和水解时间的增加而增加,其中4％NaOH和10×10~5 Gy处理的稻麦秸秆第6天的葡萄糖得率为19％和22％。     

固定化唾液链球菌生产γ-氨基丁酸的研究

以唾液链球茵嗜热亚种(Streptococcus salivarius subsp.thermophilus Y-2)为供试菌株,考察了卡拉胶、明胶和海藻酸钙等材料将此菌株固定化的效果,并通过比较固定化细胞的谷氨酸脱羧酶(glutamatedecarboxylase,GAD)活性及γ-氨基丁酸的产量和载体机械强度,确定了海藻酸钙作为固定化细胞的适宜载体.优化后得到的最适固定化条件(W/V)为:海藻酸钠2%,CaCl_2 14%,茵体25%,凝胶平均颗粒直径1.64 mm,在此条件下测得固定化细胞的GAD活性为游离细胞的1.2倍.细胞多批次应用稳定性试验证明:固定化细胞较游离细胞有着更稳定的GAD活性,反复使用60 h后,固定化细胞GAD活性仍能保持其初始活性的90%以上,γ-氨基丁酸的积累量达到7.97 g/L.     

Isolation of homogeneous fractions from wheat water-soluble arabinoxylans. Influence of the structure on their macromolecular characteristics

Water-soluble arabinoxylans from wheat flour were purified and fractionated by graded ethanol precipitation. Six fractions were obtained at 20% (F20), 30% (F30), 40% (F40), 50% (F50), 60% (F60), and 70% (F70) saturation with ethanol. Neutral sugars and (1)H NMR analyses revealed differences in structural characteristics. The Ara/Xyl ratio and the amount of Xylp residues disubstituted increased with ethanol concentration. Ferulic acid content was higher in fractions precipitated at low ethanol percentage. Fractions were refractionated by SEC, leading to 46 subfractions with low polydispersity index. Substitution degree was apparently linearly related to the amount of disubstituted Xylp. Macromolecular characteristics (M(w), [eta], R(G), q, nu) determined by multiangle laser light scattering and viscosimetry were similar among all fractions. A rather flexible conformation was determined for the arabinoxylans, in conflict with the admitted rodlike conformation. The substitution degree had no influence on the conformation or on the rigidity of the polymers. Evidence for the presence of ferulic acid dimers in the water-soluble arabinoxylans is provided, which probably explains the unexpected conformation and macromolecular characteristics.     

Mathematical model of sugar uptake in fermenting yeasted dough

Fermentation prior to freezing significantly reduces the shelf life of frozen dough, measured as a decline in proofing power. Changes during fermentation caused by yeast metabolism have previously been described empirically on a dough weight basis and have not been mathematically modeled. In this work, yeast metabolites were quantified in fermenting dough and their concentrations were estimated in the aqueous environment around yeast cells. The osmotic pressure in the aqueous phase increases by 23% during 3 h of fermentation, which depresses the freezing point by 1 degrees C. The rise in osmotic pressure and the accumulation of ethanol may affect phase equilibria in the dough, baking properties, and the shelf life of frozen dough. Predictive modeling equations fitted sugar concentration data accurately. It was found that the preference of baker's yeast for glucose over fructose was stronger in fermenting dough than in liquid fermentations. The usefulness of the model in industrial bakery formulation work was demonstrated.