木糖醇大规模发酵生产策略

<正>发酵工艺是木糖醇生产的发展方向,其通过生物选择性催化,大幅度简化了原料预处理步骤和产物分离过程,有效提高从原料到产物的收率。文章对木糖醇大规模发酵生产中的主要技术环节,包括原料选择、水解方法、水解物脱毒与净化、微生物菌种选择、发酵过程与产物分离等问题进行了系统评述,并对这些关键环节的工艺策略选择提出了笔者的观点。     

黄姜皂素提取工艺研究

以黄姜为原料,研究皂素提取的生产工艺。通过对几种工艺的比较,确定一种先分离黄姜中纤维素及淀粉,再经过酸水解、中和提取皂素的方法。该法黄姜皂素的平均得率为传统方法的86.56%,用酸量仅为传统方法的9.62%,同时分离得到46.44%的纤维素和32.75%的淀粉。该法资源综合利用率明显提高,并大幅度减少废水的生成,减少环境污染,节约原料、能源,生产周期也明显缩短。     

源清天木:开发高效菌株育种技术提升生物产业创新能力

<正>生物产业是我国一项战略性新兴产业。我国生物产业发展已有30多年的历史,近年来更是以每年20%以上的速度增长。然而,我国生物产业大多处于整个生物产业链的底端,多以生产和出口原料为主,企业竞争力主要来自于低廉的劳动力和资源,整个产业缺乏有效大幅度提升生产效率的     

利用木质纤维素生产丁醇的研究进展

随着化石燃料的逐年减少,以生物质为原料的生物能源研究近年来成为能源领域的研究热点,充分利用可再生生物质为发展经济的生物燃料生产工艺提供了一个极好的机会。与燃料乙醇和生物柴油相比,生物丁醇更具有优越性,以可再生木质纤维素生物质为原料进行发酵生产丁醇在近年来被广泛的研究。对于利用可再生生物质为原料生产丁醇,需要解决原料的选择、产品收率低、抑制物对生产菌株毒性等问题。本文对以木质纤维素生物质为原料进行生物丁醇发酵过程中的原料预处理、抑制物对丁醇生产菌的影响,以及水解液的脱毒和耐抑制物菌株的选育等方面进行综述,并对以木质纤维素生产燃料丁醇所面临的机遇与问题进行了简要评述。     

生物质的综合利用技术在燃料乙醇产业中的应用

概述了燃料乙醇生产的生物质及其特点,重点阐述了小麦、玉米等原料生产乙醇的综合开发技术,并对甘蔗和木薯为原料生产燃料乙醇进行了经济性评价。     

生物质原料发酵生产丁二酸研究进展

以生物质为原料微生物发酵生产丁二酸,对于减少化工产品对石化原料的依赖,保护环境有积极的意义.本文通过介绍目前用乳清、糖蜜、菊粉、甜高粱、小麦淀粉、木质纤维素等廉价原料生产丁二酸的研究近况,展现了非粮原料生产丁二酸的良好的应用前景.     

葡萄糖母液摇瓶发酵生产柠檬酸

深层发酵生产柠檬酸,国内主要以薯干为原料。而利用葡萄糖母液为原料发酵生产柠檬酸,国内尚无报道。为此我们进行了菌种选育和发酵条件试验的研究。     

决胜纤维素

<正>纤维素乙醇的产业化受到全球越来越多的国家的重视,其原因、其目的不言而喻。以粮食和油料作为原料生产第一代生物燃料的产业,正受到政府机构、环境保护主义者以及广大消费者越来越多的指责。与玉米等粮食为原料的第一代生物燃料形成对比的是,用稻草、秸秆等植物纤维为原料生产的第二代生物燃料,具有原料不与粮食竞争而且整个生产过程排放的CO_2量少等优势。     

利用木薯淀粉产异丁醇的重组菌株的构建

目的:构建了一株直接利用木薯淀粉为原料生产异丁醇的重组菌株。方法:将地衣芽孢杆菌的淀粉酶基因克隆到生产异丁醇的大肠杆菌重组菌中,使大肠杆菌能够直接利用木薯淀粉为原料生产异丁醇。结果:木薯淀粉不需要预先加入淀粉酶进行糖化处理,就可以直接被作者研究所构建的重组菌株发酵生成异丁醇。结论:提供了一种直接发酵木薯淀粉生产异丁醇的方法。导入地衣芽孢杆菌的淀粉酶基因,能使只能利用葡萄糖作为发酵材料的异丁醇生产工程菌直接利用木薯淀粉为原料生产异丁醇。     

巴西首家“绿色塑料”工厂投产

巴西石化工业巨头Braskem公司于2010年9月24日在南大河州石化基地举行以甘蔗乙醇为原料生产聚乙烯工厂的投产揭牌仪式,这是全世界首家以生物材料为原料的成规模聚乙烯工厂,该厂年产聚乙烯20万t。新投产的以甘蔗乙醇为原料生产的聚乙烯,通过加温、脱水、提纯、压缩、清洗、浓缩等工序制成,被称作“绿色塑料”,     

Itaconic acid production by Aspergillus terreus on raw starchy materials

Starchy materials such as corn starch, soft wheat flour, potato flour, cassava flour, sorghum starch, sweet potato and industrial potato flours, either acid or enzymatically hydrolysed, were used as substrates for itaconic acid production by Aspergillus terreus NRRL 1960. Both production and yield were highest on corn starch (18·4 g l⁻¹ and 34·0%, respectively). The degree of hydrolysis had a great influence on acid production which was highest when corn starch was saccharified at 85 DE (dextrose equivalent). In a 3 litre benchtop fermenter, itaconic acid production and productivity were 19·8 g l⁻¹ and 0·13 g l⁻¹ h⁻¹, respectively.     

四川间作地区作物高度、覆盖度和叶面积指数的动态变化

为研究间作系统的作物参数,于2005年在四川间作地区进行了作物高度、覆盖度和叶面积指数的时间变化研究.结果表明:作物的高度、覆盖度和叶面积指数随时间变化很大;玉米的最大高度是177 cm,最大覆盖度(86%)出现在花期,最大叶面积指数是1.96;红苕的最大和最小株高分别为22和12 cm,最大覆盖度(73%)出现在薯块膨大期,最大叶面积指数为1.79.与玉米间作时,红苕所有作物参数均受玉米影响.在玉米-红苕间作系统中,最危险的侵蚀期是玉米收获后至红苕覆盖度最大期.     

植酸钠对黑曲霉柠檬酸发酵产酸的促进效应

研究了植酸钠对黑曲霉柠檬酸发酵产酸的促进效应。在葡萄糖全合成培养基中添加１％的植酸钠,可使产酸比对照提高２．４倍;在薯粉、玉米粉等天然培养基中添加１％植酸钠,柠檬酸产量分别提高１．７倍和１．３倍。酶活性测定分析表明,植酸钠对柠檬酸代谢途径中的几种关键酶的活性有影响。     

Changes in caffeic acid derivatives in sweet potato (Ipomoea batatas L.) during cooking and processing

There was an obvious decrease in caffeic acid derivatives during the boiling of cube-shaped blocks of sweet potatoes. They also decreased in a mixture of freeze-dried sweet-potato powder and water maintained at room temperature. Ascorbic acid prevented the decrease, supporting the occurrence of an enzyme reaction with polyphenol oxidase (PPO). 5-O-Caffeoylquinic acid (5-CQA, "3-O-caffeoylquinic acid" as a trivial name) and 3,5-di-O-caffeoylquinic acid (3,5-CQA), major phenolic compounds of sweet potato, did not change when they were separately heated in boiling water. When the mixture of powdered sweet potato and water was heated at 100 degrees C, there was only a negligible decrease in the total amount of phenolic compounds, and portions of 5-CQA and 3,5-CQA were found to be isomerized to 3-CQA, 4-CQA, 3,4-CQA, and 4,5-CQA. The content and composition of the phenolic compounds in sweet potatoes differed between fresh and long-stored ones, as did their response to heating.     

Nematode Numbers and Crop Yield in a Fenamiphos-Treated Sweet Corn-Sweet Potato-Vetch Cropping System

Nematode population densities and yield of sweet corn and sweet potato as affected by the nematicide fenamiphos, in a sweet corn-sweet potato-vetch cropping system, were determined in a 5-year test (1981-85). Sweet potato was the best host of Meloidogyne incognita of these three crops. Fenamiphos 15G (6.7 kg a.i./ha) incorporated broadcast in the top 15 cm of the soil layer before planting of each crop increased (P ≤ 0.05) yields of sweet corn in 1981 and 1982 and sweet potato number 1 grade in 1982 and 1983. Yield of sweet corn and numbers of M. incognita second-stage juveniles (J2) in the soil each month were negatively correlated from planting (r = - 0.47) to harvest (r = -0.61) in 1982. Yield of number 1 sweet potato was inversely related to numbers of J2 in the soil in July-October 1982 and July-September 1983. Yield of cracked storage roots was positively related to the numbers of J2 in the soil on one or more sampling dates in all years except 1985. Some factor(s), such as microbial degradation, resistant M. incognita development, or environment, reduced the effect of fenamiphos.     

Influence of the glycolytic rate on production of citric acid and oxalic acid by Aspergillus niger in solid state fermentation

A study was performed to understand the physiology and biochemical mechanism of citric acid accumulation during solid state fermentation of sweet potato using Aspergillus niger Yang No.2. A low citrate-producing mutant was isolated followed by a comparative study of the fermentation process and selected physiological and biochemical parameters. In contrast with the parent strain, the mutant strain displayed lower concentrations, yields and production rates of citric acid, accompanied by higher concentrations, yields and production rates of oxalic acid. In addition, the mutant utilized starch at a lower rate although higher concentrations of free glucose accumulated in the cultures. Biochemical analyses revealed lower rates of glucose uptake and hexokinase activity of the mutant strain in comparison with the parent strain. It is proposed that, in common with submerged fermentation, over-production of citric acid in solid state fermentation is related to an increased glucose flux through glycolysis. At low glucose fluxes, oxalic acid is accumulated.     

Influence of preceding crop on wireworm (Coleoptera: Elateridae) abundance in the coastal plain of North Carolina

Three studies were conducted to determine the effect of preceding crop on wireworm (Coleoptera: Elateridae) abundance in the coastal plain of North Carolina. In all three studies, samples of wireworm populations were taken from the soil by using oat, Avena sativa L., baits. Treatments were defined by the previous year's crop and were chosen to reflect common crop rotations in the region. Across all three studies, eight wireworm species were recovered from the baits: Conoderus amplicollis (Gyllenhal), Conoderus bellus (Say), Conoderus falli (Lane), Conoderus lividus (Degeer), Conoderus scissus (Schaeffer), Conoderus vespertinus (F.), Glyphonyx bimarginatus (Schaeffer), and Melanotus communis (Gyllenhal). The effect of corn, Zea mays L.; cotton, Gossypium hirsutum L.; fallow; soybean, Clycine max (L.) Merr.; sweet potato, Ipomoea batatas (L.) Lam.; and tobacco (Nicotiana spp.) was evaluated in a small-plot replicated study. M. communis was the most frequently collected species in the small-plot study and was found in significantly higher numbers following soybean and corn. The mean total number of wireworms per bait (all species) was highest following soybean. A second study conducted in late fall and early spring assessed the abundance of overwintering wireworm populations in commercial fields planted to corn, cotton, peanut (Arachis hypogaea L.), soybean, sweet potato, and tobacco in the most recent previous growing season. C. lividus was the most abundant species, and the mean total number of wireworms was highest following corn and soybean. A survey was conducted in commercial sweet potato in late spring and early summer in fields that had been planted to corn, cotton, cucurbit (Cucurbita pepo L.), peanut, soybean, sweet potato, or tobacco in the most recent previous growing season. C. vespertinus was the most abundant species, and the mean total number of wireworms per bait was highest following corn.     

甘薯提取物对谷氨酸所致PC12细胞损伤的保护作用初探

观察甘薯提取物对谷氨酸诱导的PC12细胞损伤的保护作用.将大鼠嗜铬细胞瘤细胞(PC12)分为空白对照组、模型组、甘薯提取物0.1、1.0、10.0 μg/mL低、中、高剂量组和1.0 μmol/L尼莫地平阳性药物对照组,用2.0 mmol/L谷氨酸造成PC12细胞损伤,MTT法测定损伤细胞的存活率,观察其细胞损伤的形态学变化,考察甘薯提取物对谷氨酸所致PC12细胞损伤的保护作用.结果表明甘薯提取物可明显提高谷氨酸诱导的PC12损伤细胞存活率,同时能够明显改善谷氨酸诱导的PC12损伤细胞的细胞形态变化,并呈现剂量相关性,具有一定的神经营养及保护作用.     

甘薯茎尖与常见叶菜类蔬菜氨基酸含量及组成的比较分析

选用叶菜型甘薯茎尖和14种常见叶菜类蔬菜为材料,对比分析了氨基酸含量及组成。结果表明:甘薯茎尖含有18种氨基酸,种类齐全。氨基酸总量、人体必需氨基酸含量和儿童必需氨基酸含量均居第1位。甘薯茎尖的E/T值为39.50%,E/N值为0.65,符合理想蛋白质的要求。茎尖中各种人体必需氨基酸含量占氨基酸总量的比例(Val、Ile、Leu、Phe+Tyr、Lys、Thr)与1973年FAO/WHO修订的人体必需氨基酸含量模式谱基本一致,仅M et+Cys中度缺乏。甘薯茎尖中鲜味类、芳香族、甜味类氨基酸含量居第1位。     

Trypsin inhibitors in plants

Trypsin inhibitors were found in several food plants. Potato and sweet corn were the most inhibitory, while fruits had negligible activity. Intermediate in activity were sweet potato, spinach, broccoli, Brussels sprouts and cucumber. The trypsin inhibitor of sweet corn was isolated by extraction in dilute salt solution, ammonium sulfate fractionation, chromatography with Sephadex G75 and CM-cellulose and lyophilization. Two components were demonstrated by disc gel electrophoresis. The inhibitor was heat stable. It had little inhibitory activity against papain but was moderately active against chymotrypsin.