利用多菌种混合发酵转化玉米秸秆的研究

该文系统地研究了高产纤维素酶生产菌（ＴｒｉｃｈｏｄｅｒｍａｒｅｓｉＴＢ９７０１）与饲料酵母混合共发酵玉米秸秆粉对合成菌体蛋白质和利用纤维素的关系,优选出一条最佳的共发酵工艺途径和条件。研究表明在以氨法处理的玉米秸秆为底物的ＴＢ－９７０１与饲料酵母菌的混合菌共发酵正交实验中,于ｐＨ５．０,３０℃的条件下２００ｒ／ｍｉｎ的恒温、恒速摇瓶培养８ｄ,经测定发酵液终产物中粗蛋白（ＳＣＰ）的含量达到了２３．７０％,总秸秆纤维的转化率达到７０％以上。     

玉米秸秆分批补料获得高还原糖浓度酶解液的条件优化

木质纤维素高浓度还原糖水解液的获得是纤维乙醇产业化发展的方向。在发酵工业领域,分批补料法是实现这一目标的重要研究途径。本研究采用分批补料法对获得高浓度玉米秸秆酶解还原糖的条件进行了优化。以稀硫酸预处理的玉米秸秆为原料,考察了液固比、补加量与补加时间对分批补料糖化的影响。结果表明,秸秆高浓度酶解液条件的初始物料为20％ (重量/体积),木聚糖酶220 U/g (底物),纤维素酶6 FPU/g (底物),果胶酶50 U/g (底物),在24 h、48 h后分批补加8％预处理后的物料,同时添加与补料量相应的木聚糖酶20 U/g (底物),纤维素酶2 FPU/g (底物),72 h后,最终糖化结果与非补料法相比,还原糖浓度从48.5 g/L提高到138.5 g/L,原料的酶解率最终达到理论值的62.5％。试验结果表明补料法可以显著提高秸秆水解液还原糖浓度。     

虎掌菌菌丝富硒培养的研究

为生产合适的硒源提供一种思路,以菌丝体生物量、含硒量、还原糖、氨态氮和蛋白质为指标,采用四因素三水平正交设计法优化虎掌菌的富硒发酵条件,探讨不同浓度的硒对虎掌菌固体培养菌丝生长和液体培养产生的生物组分的影响。结果表明,高浓度的硒抑制虎掌菌菌丝体生长;正交试验选择不同的衡量指标,由极差分析得出各因素的影响程度大小,结合证实试验得到以还原糖为指标的最优组合为葡萄糖6%(质量分数)、酵母浸膏3%(质量分数)、KH_2PO_4 0.1%(质量分数)、Na_2SeO_3 0.6 mmol/L,其菌丝体生物量和氨态氮含量较高。与对照相比,加硒后虎掌菌发酵液中氨态氮、还原糖和总糖含量显著增加(P0.05);当硒浓度为0.5 mmol/L时,氨态氮、还原糖和总糖含量均达到最高值。菌丝体生物量和可溶性蛋白质分别在硒浓度为0.2 mmol/L和0.4 mmol/L时达到最大值。虎掌菌富硒培养后,发酵液的营养成分含量会发生变化。     

自絮凝颗粒酵母乙醇连续发酵耦合废液全循环工艺的研究

在以CO2为驱动力的单级悬浮床生物反应器中,进行了自絮凝颗粒酵母乙醇连续发酵耦合废液全循环实验研究。以双酶法制备的玉米粉糖化液为底物,系统连续运行了28 d,每隔5 d将收集到的发酵液集中精馏处理,得到的废糟液直接用于玉米粉调浆制糖。实验数据表明,在稀释率为0.05 h-1条件下,发酵液中乙醇、残还原糖、残总糖质量浓度基本稳定,其平均值为82.97,30.02和40.87 g.L-1。对废液循环工艺过程中,发酵液中的8种高沸点有机酸进行了定量分析,发现发酵液中仅丙酮酸有明显积累,并最终在0.1~0.3 mol.L-1范围内波动。实验结果表明:系统中存在的高沸点副产物不对乙醇发酵产生明显抑制作用,乙醇连续发酵能够在废液全循环条件下良好运行。     

拜氏梭菌Clostridium beijerinckii NCIMB 8052发酵玉米皮生产丁醇

玉米皮作为玉米淀粉加工的副产物,是一种可用于生产液体燃料的潜在廉价优质的生物质资源。本文以玉米皮为原料,对拜氏梭菌发酵生产丁醇进行了研究。实验结果表明,玉米皮首先在最优的预处理温度140℃下使用0.5%硫酸水溶液以固液比1∶8处理20 min,再添加200 IU/g底物糖化酶、1.0 IU/g底物木聚糖酶进行酶解,可以使原料中的淀粉和半纤维素转化为可发酵糖,此时水解液中的总糖浓度为50.46 g/L。然后使用1.0%的活性炭对水解液进行脱毒处理以去除发酵抑制物,再进行丁醇发酵,丁醇产量为9.72 g/L,总溶剂产量可达14.09 g/L,糖醇转化率为35.1%。上述研究结果证明玉米皮作为一种粮食加工废弃物用于液体燃料丁醇的生产在技术上是完全可行的。     

白腐真菌Pleurotus sajor-caju预处理对红麻秸秆发酵乙醇的影响

为研究微生物法预处理对红麻秸秆中木质素的降解及后续的红麻纤维素酶促糖化和发酵效率的影响,将白腐真菌Pleurotus sajor-caju接种在红麻秸秆培养基上固态培养,对红麻秸秆进行预处理。经P. sajor-caju培养25~35 d后,有效转化红麻秸秆中的木质素,转化率最高可达50.20％,并提高红麻纤维素的酶促水解效率,糖化率达69.33％~78.64％,与对照组相比提高了3.5~4.1倍。以微生物法预处理后的红麻秸秆样品为底物的同步糖化发酵实验表明,发酵72 h,发酵液中乙醇浓度达到18.35~     

酵母发酵玉米秸秆水解液产麦角甾醇应用研究

生物质是一种可再生资源,生物质发酵可产生高端化工产品.本文主要探讨蒸汽爆破处理玉米秸秆及水解可发酵单糖,考察酵母发酵玉米秸秆糖化液产麦角甾醇的应用研究.实验结果表明:当固液比10%,盐酸浓度1.5%,90℃水解反应3 h,还原糖含量达到53.3%,纤维素转化率79%.发酵工艺参数为玉米秸秆糖化液6.0°Bx,玉米浆4%,pH 7.5,接种量10%,28℃摇床振荡培养32 h,细胞生物量达8.5 g/L,麦角甾醇含量可达2.35%.同时对玉米秸秆发酵产麦角甾醇晶体进行结构表征.     

黄原胶降解菌BIT-BJ001培养条件的优化

黄原胶在采油工程中有重要的应用,但其难降解性质给采油工程带来很多问题。从塔里木油田胡杨木根部样品中分离得到1株黄原胶降解菌BIT-BJ001,对其发酵条件的研究表明,此黄原胶降解菌最适培养条件为:黄原胶0.3%,酵母粉0.5%,Na+浓度0.8%,Mg2+浓度0.8%,初始pH值为10,温度60℃。菌种BIT-BJ001降解黄原胶的能力与发酵时间、发酵液中还原糖浓度有关,发酵96 h,黄原胶降粘率达到最高,发酵液中还原糖浓度过高,将抑制菌株对黄原胶的降解。     

沙葱对牛瘤胃体外发酵参数和产气量的影响

目的探究添加沙葱对牛瘤胃体外发酵和产气量的影响。方法实验分为对照组(以玉米秸秆为发酵底物)和沙葱处理组(在发酵底物中添加沙葱),每组设置3个重复,于不同时间节点记录2组的产气量,并在发酵72 h后对发酵液的pH值、氨态氮以及挥发性脂肪酸进行测定。结果 12、24和72 h时,2组产气量具有一定差异,在12 h时沙葱处理组显著高于对照组(t=3.717,P=0.020 5),而24 h及72 h时沙葱组产气量极显著高于对照组(t=4.832,P=0.008 5;t=4.953,P=0.007 7)。发酵72 h时对发酵液pH值及氨态氮进行测量发现沙葱组pH值显著高于对照组(t=3.949,P=0.017 0),而对照组的氨态氮含量极显著高于沙葱组(t=-4.806,P=0.009 0)。2组挥发性脂肪酸的含量差异无统计学意义。结论在体外发酵条件下添加沙葱对瘤胃微生物发酵状态具有一定的调节作用,沙葱作为反刍动物使用的植物提取物饲料添加剂具有潜在价值。     

食用真菌蛋白——美味丝葚霉D-100的研究——Ⅲ.丝状真菌连续发酵的研究

本文研究了以丝状真菌D-100直接利用淀粉连续发酵的工艺条件。通过氮源试验,摇瓶生长曲线和发酵罐生长曲线的对比试验,发酵过程中淀粉糖化酶的定量检测,以及连续发酵过程中四个主要参数在三水平上的正交试验,确定了以0.1—0.2%NH_4NO_3为氮源,0.5%玉米粉为碳源,稀释速率D值为0.15,搅拌转速为200 r/min,pH 5.5的条件为最佳连续发酵条件。连续发酵结果是:以玉米淀粉为底物的菌体产率是37.5%,其菌体蛋白质含量38.5%,发酵罐效率是0.35g菌体干重/L·h,试验还证明该菌淀粉糖化酶的生成受还原糖的反馈控制,故发酵过程培养基中还原糖浓度衡定在一定值。培养基浓度增加时,超过玉米粉浓度1.25%以上其比生长速率不明显增加。     

Reconstitution of light-independent protochlorophyllide reductase from purified bchl and BchN-BchB subunits. In vitro confirmation of nitrogenase-like features of a bacteriochlorophyll biosynthesis enzyme

Protochlorophyllide reductase catalyzes the reductive formation of chlorophyllide from protochlorophyllide during biosynthesis of chlorophylls and bacteriochlorophylls. The light-independent (dark) form of protochlorophyllide reductase plays a key role in the ability of gymnosperms, algae, and photosynthetic bacteria to green (form chlorophyll) in the dark. Genetic and sequence analyses have indicated that dark protochlorophyllide reductase consists of three protein subunits that exhibit significant sequence similarity to the three subunits of nitrogenase, which catalyzes the reductive formation of ammonia from dinitrogen. However, unlike the well characterized features of nitrogenase, there has been no previous biochemical characterization of dark protochlorophyllide reductase. In this study, we report the first reproducible demonstration of dark protochlorophyllide reductase activity from purified protein subunits that were isolated from the purple nonsulfur photosynthetic bacterium Rhodobacter capsulatus. Two of the three subunits (Bchl and BchN) were expressed in R. capsulatus as S tag fusion proteins that facilitated affinity purification. The third subunit (BchB) was co-purified with the BchN protein indicating that BchN and BchB proteins form a tight complex. Dark protochlorophyllide reductase activity was shown to be dependent on the presence of all three subunits, ATP, and the reductant dithionite. The similarity of dark protochlorophyllide reductase to nitrogenase is discussed.     

突变哈茨木霉H-13对小白菜生长和品质的影响

用N＋离子束诱变哈茨木霉,得到促生长突变型哈茨木霉H-13,用不同浓度的哈茨木霉H-13发酵液浸种处理小白菜种子,对幼苗进行灌根处理发现,发酵液稀释100倍和200倍处理,提高了种子的活力指数、植株鲜重和叶绿素含量,增加了植株体内可溶性还原糖和可溶性蛋白的含量,降低了植株体内硝酸盐和亚硝酸盐的含量.     

Pilot-scale semisolid fermentation of straw

Semisolid fermentation of ryegrass straw to increase its animal feed value was successfully performed on a pilot scale. The pilot plant, which could handle 100 kg of straw per batch, was designed so that all major operations could take place in one vessel. The straw was hydrolyzed at 121 degrees C for 30 min with 0.5 N H2SO4 (7:3 liquid:solid), treated with ammonia to raise the pH to 5.0, inoculated with Candida utilis, and fermented in a semisolid state (70% moisture). During fermentation the straw was held stationary with air blown up through it. Batch fermentation times were 12 to 29 h. Semisolid fermentation did not require agitation and supported abundant growth at 20 to 40 degrees C even at near zero oxygen tensions. Fermentation increased the protein content, crude fat content, and in vitro rumen digestibility of the straw.     

Pilot-scale semisolid fermentation of straw.

Semisolid fermentation of ryegrass straw to increase its animal feed value was successfully performed on a pilot scale. The pilot plant, which could handle 100 kg of straw per batch, was designed so that all major operations could take place in one vessel. The straw was hydrolyzed at 121 degrees C for 30 min with 0.5 N H2SO4 (7:3 liquid:solid), treated with ammonia to raise the pH to 5.0, inoculated with Candida utilis, and fermented in a semisolid state (70% moisture). During fermentation the straw was held stationary with air blown up through it. Batch fermentation times were 12 to 29 h. Semisolid fermentation did not require agitation and supported abundant growth at 20 to 40 degrees C even at near zero oxygen tensions. Fermentation increased the protein content, crude fat content, and in vitro rumen digestibility of the straw.     

Radiation and fermentation treatment of cellulosic wastes

The effect of radiation pasteurization of sugar cane bagasse and rice straw and fermentation using various strains of fungi were studied for upgrading of cellulosic wastes. The initial contamination by fungi and aerobic bacteria both in bagasse and straw was high. The doses of 30 kGy for sterilization and 8 kGy for elimination of fungi were required. Irradiation effect showed that rice straw contained comparatively radioresistant microorganisms. It was observed that all the fungi (Hericium erinacium, Pleurotus djamor, Ganoderma lucidum, Auricularia auricula, Lentinus sajor-caju, Coriolus versicolor, Polyporus arcularius, Coprinus cinereus) grow extending over the entire substrates during one month after inoculation in irradiated bagasse and rice straw with 3% rice bran and 65% moisture content incubated at 30°C. Initially, sugar cane bagasse and rice straw substrates contained 39.4% and 25.9% of cellulose, 22.9% and 26.9% of hemicellulose, and 19.6% and 13.9% of lignin + cutin, respectively. Neutral detergent fibre (NDF) values decreased significantly in sugar cane bagasse fermented byG. lucidum, A. auricula andP. arcularius, and in rice straw fermented by all the 8 strains of fungi. Acid detergent fibre (ADF) values also decreased in bagasse and rice straw fermented by all the fungi.P. arcularius, H. erinacium, G. lucidum andC. cinereus were found to be the most effective strains for delignification of sugar cane bagasse.     

The enzymatic hydrolysis and fermentation of pretreated wheat straw to ethanol

Autohydrolysis and ethanol-alkali pulping were used as pretreatment methods of wheat straw for its subsequent saccharification by Trichoderma reesei cellulase. The basic hydrolysis parameters, i.e., reaction time, pH, temperature, and enzyme and substrate concentration, were optimized to maximize sugar yields from ethanol-alkali modified straw. Thus, a 93% conversion of 2.5% straw material to sugar syrup containing 73% glucose was reached in 48 h using 40 filter paper units/g hydrolyzed substrate. The pretreated wheat straw was then fermented to ethanol at 43 degrees C in the simultaneous saccharification and fermentation (SSF) process using T. reesei cellulase and Kluyveromyces fragilis cells. From 10% (w/v) of chemically treated straw (dry matter), 2.4% (w/v) ethanol was obtained after 48 h. When the T. reesei cellulase system was supplemented with beta-glucosidase from Aspergillus niger, the ethanol yield in the SSF process increased to 3% (w/v) and the reaction time was shortened to 24 h.     

Ammoniation of wheat straw and native grass hay during baling of large round bales

Wheat straw and native grass hay were treated with anhydrous ammonia during baling with a large round baler. In Experiment 1, ammonia (3.2 and 7.1% w/w of straw DM) was applied by use of a Cold-flow Converter to wheat straw that either had not been sprayed or had been sprayed with one of two rates of water as it passed over the pick-up frame of the baler. Straw water concentrations immediately after baling were 13.8 and 23.8%, respectively, for the low and high rates of water application. Straw water concentrations were about 12 percentage units lower than anticipated, and indicate that water penetration of the hard cuticular surface of the straw was low. Treatment with 3.2% ammonia of straw not sprayed with water increased the crude protein content from 3.2 to 5.7% immediately after baling. However, none of the ammonia-nitrogen (NH₃-N) was retained 45 days after baling, and dry matter digestibility in vitro (IVDMD) of the straw was not increased. Straw that was treated with low levels of both ammonia and water contained 6.0% crude protein after storage, and IVDMD increased 27% (i.e., 36.7 vs. 28.9%; P < 0.001). Retention of NH₃-N after storage ranged from ?1.4 (low level of ammonia and no added water) to 14.8% (low level of both ammonia and water) and was increased (P < 0.001) by added water at the low level of ammonia application.The effects of crimping wheat straw during baling and addition of a surfactant (0.2% v/v) to aqua-ammonia on crude protein content, retention of NH₃-N and the IVDMD of straw were studied in Experiment 2. Water content of ammoniated straw in Experiment 2 (ca.14%) was similar to that of straw sprayed with the low level of water in Experiment 1. Crimping did not visibly disrupt the surface of the straw, nor affect crude protein content or IVDMD. Addition of surfactant to the aqua-ammonia increased (P < 0.01) the crude protein content after storage of non-crimped and crimped straw, respectively, by 0.3 and 1.5 percentage units (P < 0.05 for crimping by surfactant interaction). Straw IVDMD was not increased by either crimping or addition of surfactant to the aqua-ammonia. Retention of NH₃-N after storage, which ranged from 26 to 49%, was greater than that of Experiment 1, and was attributed to the lower level of ammonia application (1.7% of straw DM). Native grass hay readily adsorbed aqua-ammonia. Water content of the hay was increased from 12.2 to 28.7%, and the crude protein content was increased from 4.4 to 13.9% by ammoniation. The studies indicate that while ammoniation of crop residues during the baling operation is a possible means of treatment, low retention of NH₃-N remains a problem. Disruption of the hard cuticular surface of residues such as wheat straw may improve penetration of aqua-ammonia and therefore the effectiveness of treatment.     

食物中某些营养组分对三突花蛛生长发育的影响

研究食中可溶性蛋白、可溶性糖、总糖、铁、磷以及水等营养组分含量对三突花蛛相对取食量（RCR）和食物利用率（ECI）的影响,并建立这些组分对三突花蛛相对取食量和食物利用率的线性数学模型。     

Effects of treatment of barley straw with anhydrous ammonia and supplementation with heat-treated protein meals on feed intake and liveweight performance of growing lambs

Two feeding experiments were conducted in which lambs were given a basal diet of barley straw, supplemented with urea and minerals. The aim of the experiments was to increase lamb performance by (i) supplementation of the diet with protein meals that were largely undegraded in the rumen, (ii) treating the barley straw with anhydrous ammonia to increase its digestibility, or (iii) a combination of both.In Experiment 1, lambs were given the basal diet supplemented with 0, 60, 120, 180, 240, 300 or 360 g heat-treated protein-meal/kg straw. At the 300 g/kg level of supplementation, the protein pellet increased liveweight gain by 82 g/day, intake of barley straw by 110 g/day, and wool growth by 3.3 g/day, in comparison with unsupplemented lambs.In Experiment 2, untreated barley-straw or barley straw treated with anhydrous ammonia (4% w/w) was given to growing lambs. Each diet was supplemented (g/kg straw diet) with 100, 200 or 300 of two heat-treated protein-meals. Ammoniation of the barley straw increased dry matter (DM) digestibility in vitro from 49 to 57%, and hemicellulose content was reduced by 20%. Total N content of the straw was increased from 4.6 to 9.8 gN/kg DM by ammoniation, 65% of the increased N being potentially degradable in the rumen. As a result of ammoniation, digestible dry-matter intake of lambs was increased by 60 g DM/day and liveweight gain increased by 15 g/day.There was no significant difference between the two protein supplements with respect to either total feed intake or liveweight gain. Liveweight gain was significantly increased by both supplements (71, 106 and 125 g/day for each level of supplementation, respectively), but neither supplement had a significant effect on the intake of barley straw.Supplementation of a low-protein, low digestible diet of barley straw with a pelleted protein-meal considerably increased liveweight gain of growing lambs and maintained straw intake. By comparison, treatment of barley straw with anhydrous ammonia increased its digestibility, but had only a minor effect on lamb performance.     

小麦秸秆复合基质的理化指标及其对黄瓜幼苗生长和光合参数的影响

以小麦(Triticum aestivum L.)秸秆基质(发酵)为主,按不同比例分别添加蛭石、珍珠岩和草炭,配制10种复合基质;以不含小麦秸秆基质的复合基质为对照,对各基质的基本理化性状进行了分析和比较,并研究了不同基质对黄瓜(Cucumis sativus L.)幼苗生长、叶片叶绿素含量和光合参数的影响。结果显示:不同基质的理化指标有明显差异,小麦秸秆基质与蛭石、珍珠岩和草炭混配均降低或显著降低了基质的容重、总孔隙度、持水孔隙度、水气比、小颗粒含量、pH值和电导率,提高了通气孔隙度以及大、中颗粒的含量。按V(小麦秸秆基质)∶V(蛭石)∶V(草炭)=50∶25∶25的比例配制的复合基质T9的容重、总孔隙度、通气孔隙度、持水孔隙度、水气比和电导率分别为0.33g.cm-3、68.1%、15.3%、52.8%、3.45和3.91 mS.cm-1,理化性状最佳,具有良好的吸水和保水性能。总体上看,随复合基质中小麦秸秆基质比例的降低,黄瓜幼苗的株高、茎粗、根总长、根总体积、平均单根直径和根尖总数、生物量和壮苗指数以及叶片的叶绿素含量均呈上升趋势;复合基质中小麦秸秆基质比例较高,黄瓜叶片的净光合速率、气孔导度和蒸腾速率均较低,但与对照相比,不同基质对叶片胞间CO2浓度及水分利用效率无显著影响。在复合基质T9中黄瓜幼苗的这些生长指标、壮苗指数以及叶片叶绿素含量和光合参数总体上高于或显著高于对照和其他复合基质,生长良好。结果表明:复合基质T9较适合黄瓜幼苗的生长发育,可作为黄瓜育苗基质。