玉米浆对玉米粉和木薯淀粉发酵甘油的影响及二者的比较

以玉米粉和木薯淀粉为原料 ,比较了二者的液化和糖化 ,结果表明 :在相同条件下 ,木薯淀粉液化时间较短 ,玉米粉液化时间较长 ,但二者的液化液均较易糖化。然后分别以玉米粉和木薯淀粉糖化液为原料 ,用耐高渗酵母发酵生产甘油 ,研究了玉米浆对二者甘油发酵的影响并对二者进行了比较 ,结果表明 :当玉米粉和木薯淀粉糖化液还原糖含量分别为 2 5 % ,尿素为 0 .2 % ,pH为 4 .5时 ,用玉米粉糖化液发酵甘油时可不添加玉米浆 ,甘油产量最高可达 2 % ,而用木薯淀粉糖化液发酵甘油时 ,适宜的玉米浆为 0 .15 % ,甘油产量最高可达 4 .9%。对二者的比较结果表明 :用玉米粉糖化液为发酵原料时 ,发酵时间较短 ,残糖降低较快 ,甘油产量较低 ,在 36h之后 ,甘油开始反耗。而用木薯淀粉糖化液发酵时 ,发酵时间较长 ,残糖降低较慢 ,甘油产量较高 ,在 72h之后 ,甘油开始反耗。     

原材料对甘油发酵影响的研究

以木薯干片,木薯淀粉,玉米淀粉的水解糖为原料,采用好氧深层发酵法进行甘油发酵。以木薯干片为原料时,甘油产率最高为１１－１２％,全糖转化率为４７－４９％,发酵周期为６０－６６ｈ;而以玉米淀粉为原料,甘油产率仅８－９％,全糖转化率３８－４０％,发酵周期却需７２小时以上     

玉米浆在产甘油假丝酵母甘油发酵中的作用机理

以复合培养基和合成培养基进行比较发酵,研究了玉米浆在产甘油假丝酵母甘油发酵过程中的作用机理。结果表明:玉米浆中的磷、氮和微量元素是影响产甘油假丝酵母甘油发酵的3个关键因素。当玉米浆磷浓度为121·75mg/L(玉米浆浓度为14g/L),最大甘油转化率达到53·44%。玉米浆磷可以调节EMP途径与HMP途径之间碳架代谢流的分布,随着玉米浆浓度进一步增加,过量磷能抑制HMP途径而激活EMP途径,因而复合培养基各项发酵参数的变化非常显著。玉米浆氮对磷的调节功能有协同作用,但并不是产甘油假丝酵母甘油发酵的理想氮源。玉米浆中的微量元素能够显著提高葡萄糖的消耗速率、促进菌体的生长和增加甘油的产量。     

在GPD1中整合表达蜜二糖酶基因改善酒精发酵水平

依据同源重组的原理将来源于粟酒裂殖酵母的α-半乳糖苷酶基因mel整合到工业酿酒酵母染色体的甘油合成途径关键酶基因GPD1中,通过G418抗性筛选得到重组子。实验数据表明,重组子S．cerevisiae MG1利用蜜二糖的能力显著提高,产甘油能力下降。引入外源基因后酵母性状与亲代相比没有显著差异,但生长时具自絮凝能力。MG1分别以玉米粉、小麦淀粉为原料进行浓醪酒精发酵,与亲代工业酿酒酵母比较,发酵液乙醇浓度得到提高,甘油含量降低,蜜二糖消耗殆尽。     

甘蔗糖蜜原料耐高渗透压酵母发酵法制甘油的体会

我厂于1978年3月完成了以甘蔗糖蜜为原料,用耐高渗透压酵母——木兰球拟酵母(Torulopsis magnoliae)发酵法制甘油的五吨发酵罐试验,效果良好。既缩短了发酵时间,又提高了甘油的含量和质量。现重点介绍在探讨缩短发酵时间和提高发酵甘油的含量及质量等工作中的一些体会和做法。     

利用甜菜糖蜜发酵生产L-谷氨酸的中间试验

随着味精工业的日益发展,发酵生产L-谷氨酸的工业用粮不断增加。为开辟L-谷氨酸发酵的原料来源,扩大甜菜糖蜜综合利用的范围,我们遵照毛主席关于“备战、备荒、为人民”的教导,在党的一元化领导下,组成了以工人为主体的试验小组,进行了用甜菜糖蜜代替淀粉水解糖发酵生产L-谷氨酸的试验工作,通过     

在GPD1中整合表达蜜二糖酶基因改善酒精发酵水平*

依据同源重组的原理将来源于粟酒裂殖酵母的α-半乳糖苷酶基因m el整合到工业酿酒酵母染色体的甘油合成途径关键酶基因GPD1中,通过G418抗性筛选得到重组子。实验数据表明,重组子S.cerevisiaeMG1利用蜜二糖的能力显著提高,产甘油能力下降。引入外源基因后酵母性状与亲代相比没有显著差异,但生长时具自絮凝能力。MG1分别以玉米粉、小麦淀粉为原料进行浓醪酒精发酵,与亲代工业酿酒酵母比较,发酵液乙醇浓度得到提高,甘油含量降低,蜜二糖消耗殆尽。     

真姬菇液体发酵培养基筛选及硒富集条件优化

以真姬菇菌种为材料,采用液体摇瓶培养进行最适发酵培养基的优化,并探讨不同浓度亚硒酸钠和甘油的富硒效果。结果表明:真姬菇菌种最优液体发酵培养基为:马铃薯20%,麦麸滤液3%,可溶性淀粉3%,酵母粉0.15%,硫酸镁0.1%,磷酸二氢钾0.2%,最大生物量可达13.2 g/L;亚硒酸钠对菌丝生长有抑制作用,但可促进菌丝富硒,当其浓度为40μg/mL时,菌丝体的硒含量最大,达1.75μg/g,总体硒富集含量可达5.8μg/L发酵液;甘油对亚硒酸钠的总富硒含量有促进作用,当甘油浓度为50μg/mL时,菌丝总体硒富集含量最大,可达26.7μg/L发酵液。     

克雷伯氏肺炎杆菌LDH526产1,3-丙二醇的甘油自动流加策略

1,3-丙二醇是一种重要的化工原料,主要作为平台化合物用于合成聚酯,如聚对苯二甲酸丙二醇酯。经基因工程改造的克雷伯氏肺炎杆菌LDH526能以甘油作为唯一碳源合成1,3-丙二醇,最终发酵浓度超过90 g/L。甘油浓度是影响1,3-丙二醇合成的关键因素。为了实现对甘油浓度的精确控制,设计并优化了基于发酵动力学的甘油自动流加策略。通过将底物流加速率与易观察变量p H和发酵时间偶联,实现了发酵过程中甘油流加的自启动和甘油浓度的动态控制。发酵72 h,1,3-丙二醇的浓度可稳定超过95 g/L。自动控制甘油流加的发酵过程具有可重复性、连续性以及人工工作量少的特点,有望从实验室规模扩大到生产规模。     

响应面法优化水溶性淀粉可食膜的制备及性能

以响应面分析法(RSM)为手段研究明胶、海藻酸钠、聚乙二醇和甘油等对水溶性淀粉可食膜力学性能的影响。以明胶、海藻酸钠、聚乙二醇、甘油为单因素,以各实验结果为基础,采用Box-Behnken试验对可食膜抗拉强度为响应值的二次回归方程分析,获得优化组合。结果表明:当水溶性淀粉4.0 g时,明胶5%(0.2 g)、海藻酸钠30%(1.2 g)、聚乙二醇22%(0.88 g)、甘油16.75%(0.67 g)时(以水溶性淀粉质量计),可食膜的抗拉强度最佳,且理论预测值和验证值较为一致,分别为94.88 MPa和93.48 MPa。并对此配方下的水溶性淀粉的糊化特性及其可食膜的力学性能、水蒸气透过性等进行检测。     

令箭荷花紫色素稳定性的研究

研究了酸度、热、光、淀粉、糖、抗坏血酸、苯甲酸钠、金属离子对令箭荷花紫色素稳定性的影响。结果表明：该色素在酸性、中性稳定;光、热对色素有一定的降解作用;淀粉、糖、抗坏血酸、Na＋、Zn2＋对色素无不良影响;苯甲酸钠、Fe3＋、Cu2＋对色素有一定影响。     

Evaluation of unrefined glycerine pitch as an efficient renewable carbon resource for the biosynthesis of novel yellow-pigmented P(3HB-co-4HB) copolymer towards green technology

Discharging the unrefined glycerine, a by-product from biodiesel production is the simplistic solution adopted for its management which has led to its price reduction in the market worldwide and created serious environmental impact. Therefore, we have explored the application of unrefined glycerine pitch as direct fermentative substrate in the biosynthesis of novel yellow-pigmented poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] copolymer by Cupriavidus sp. USMAHM13 through onestage cultivation. Utilization of glycerine pitch (10 g/L) together with 1,4-butanediol (5 g/L) had resulted in the highest achievement of 2.91 g/L of P(3HB-co-40%4HB) copolymer which was naturally dyed with the yellow pigment through the co-extraction process. Enhancement of 4HB monomer accumulation was also attained through the addition of ammonium acetate as nitrogen source. It was revealed that utilization of recovered crude glycerine from glycerine pitch was more preferred compared to the other recovered components. Utilization of glycerine pitch in the biosynthesis of P(3HB-co-4HB) copolymer would not only contribute to the efficient waste management but also would promote the development of cost-efficiency microbial fermentation.     

High- and low-purity glycerine supplementation to dairy cows in early lactation: effects on silage intake,milk production and metabolism

This study evaluated the effects of supplemental low- and high-purity glycerine on silage intake, milk yield and composition, plasma metabolites and body condition score (BCS) in dairy cows. A total of 42 cows of the Swedish Red Breed, housed in individual tie stalls, were fed 0.25 kg of low- or high-purity glycerine on top of concentrate, twice daily, during the first 4 weeks of lactation. One-third of the cows acted as controls, receiving no glycerine. Silage was fed for ad libitum intake and concentrate was fed at restricted level of intake, about 6 kg/day for primiparous cows and 7 kg/day for multiparous cows. Feed refusals were weighed daily. Cows were milked twice daily, milk yield was recorded on four occasions per week and milk samples were collected simultaneously. Blood samples were drawn from the coccygeal vessel once a week. Low- and high-purity glycerine had no effect on silage or total dry matter intake (P = 0.38 and P = 0.75, respectively) or on BCS (P = 0.45). Cows fed high-purity glycerine tended to have higher milk yield than control cows (P = 0.06). Milk composition tended to differ among treatments. No main effects of treatment on concentration of glycerine (P = 0.44), glucose (P = 0.78), insulin (P = 0.33), non-esterified fatty acids (P = 0.33) and β-hydroxybutyrate (P = 0.15) in plasma. These data indicate that high-purity glycerine has the potential to increase milk yield, as well as enhance the milk protein concentration and milk fat + protein yield.     

The use of an EGG agar medium with neutral red for the differentiation betweenM. Tuberculosis and acid-fast saprophytes

Summary Differentiation between acid-fast saprophytes andM. tuberculosis is possible by the addition of neutral red to the B medium. Acid-fast saprophytes split amylum and produce a violet colour, whereasM. tuberculosis do not split amylum, so that the brown colour is maintained.     

Intake,feeding behaviour,digestibility, performance,carcass characteristics and meat quality of lambs fed different levels of semi-purified glycerine in the diet

The aim of this study was to evaluate the effect of different inclusion levels of semi-purified glycerine in the diet of feedlot lambs on feeding behaviour, nutrient intake and digestibility, carcass characteristics, meat quality and in vitro degradability. Thirty-two Dorper × (Texel × Suffolk) crossbred intact male lambs (22.2 ± 5.51 kg) were fed glycerine (90% purity) at 0, 120, 240 or 360 g/kg dry matter (DM) in a total mixed ration with a roughage to concentrate ratio of 40:60 for 84 d. In vitro degradability was not affected by glycerine supplementation. Feeding behaviour and digestibility of DM, crude protein and fibre and production performance were similar among treatments. Ether extract digestibility was lower at the highest inclusion level. Glycerine level had no effect on ruminal pH, carcass characteristics and meat quality, except for subcutaneous fat thickness which was lower for lambs fed glycerine at 240 and 360 g/kg DM. Scores for unpleasant taste, unpleasant odour, succulence and softness of meat were not affected by dietary glycerine level. These data suggest that there are no adverse effects on carcass quality and performance when semi-purified glycerine is provided up to 360 g/kg DM in the diet of growing lambs fed a forage to concentrate ratio of 40:60.     

Kinetic study of the velum formation by Saccharomyces cerevisiae (beticus ssp.) during the biological aging of wines

The main objetive of this work was to evaluate and model the biofilm growth of the Saccharomyces cerevisiae (beticus ssp.) yeast during the biological aging of some types of wines. Thus, we have study how the biofilm growth, the glycerine is consumed and the acetaldehyde is produced, and how this phenomena are affected by the media ethanol concentration (0–17%, v/v), under experimental conditions similar to the industrial ones. In consequence, the growth of the S. cerevisiae (beticus ssp.) biofilm on the surface of the liquid was studied and kinetically modelled. Growth curves were fitted by using general kinetic models that include biomass and substrate inhibition factors. The alcohol content of the medium for the fastest growth rate of biofilm was found to be 4.3%, v/v. The proposed kinetic models for biomass growth, glycerine consumption and acetaldehyde formation fit well with the experimental data.The growth kinetics of S. cerevisiae beticus ssp. in biofilm phase presents a typical discontinuous microbial growth profile (with lag, exponential and stationary phases). The glycerine consumption is directly related to the substrate concentrations (ethanol and glycerine). Finally, the rate of acetaldehyde formation suggests a model associated with the rate of microbial growth, which is modified by a substrate-dependent factor. The suggested model can be used for optimization and control processes of biological aging of wines.     

Genetic improvement of Saccharomyces cerevisiae for xylose fermentation

There is considerable interest in recent years in the bioconversion of forestry and agricultural residues into ethanol and value-added chemicals. High ethanol yields from lignocellulosic residues are dependent on efficient use of all the available sugars including glucose and xylose. The well-known fermentative yeast Saccharomyces cerevisiae is the preferred microorganism for ethanol production, but unfortunately, this yeast is unable to ferment xylose. Over the last 15 years, this yeast has been the subject of various research efforts aimed at improving its ability to utilize xylose and ferment it to ethanol. This review examines the research on S. cerevisiae strains that have been genetically modified or adapted to ferment xylose to ethanol. The current state of these efforts and areas where further research is required are identified and discussed.     

A Note on the Staining of the Skeleton of Cleared Specimens with Alizarin Red S

A selective, progressive method for staining the skeleton in cleared specimens, developed with rat material.

Fix in 95% alcohol for at least 48 to 96 hrs. Even longer fixation is desirable. Then place in a 1% solution of KOH until the bones are clearly visible through the surrounding tissues. Transfer directly to a dilute solution of alizarin in KOH, one part alizarin to 10,000 parts of 1% KOH. Allow the stain to act until the desired intensity is attained. Fresh stain may be added if necessary.

Complete the clearing process, (1) in Mall's solution, water 79 parts, glycerine 20 parts and KOH 1 part; (2) in increased concentrations of glycerine. Store in pure glycerine.

The success of the method depends on obtaining the proper degree of clearing before staining. If the specimen is insufficiently cleared, a general staining of all tissues usually occurs.     

An acetylcholinesterase method for in toto staining of peripheral nerves.

Stomach, small intestine, uterus, urinary bladder, vagina, mesentery, mesometrium and joint capsule of rats, gall bladder, cystic duct and bile duct of dogs and uteri of young children are stained in toto. Procedure: Tissue is perfused with saline containing hyaluronidase, then pinned on a flat layer of Paraplast and fixed for 24 hr in cold sucrose formol solution. Stomach, urinary bladder and gall bladder are also fixed in toto. Rinse for 2 days in cold 0.22 M sucrose in a sodium cacodylate buffer pH 7.2. Incubate in medium consisting of 60 mM acetate-buffer pH 5.0 or pH 5.6 (for human material only), 2 mM acetylthiocholine iodide, 15 mM Na citrate, 3 mM Cu sulphate, 0.5 mM K3Fe(CN)6, 5 times 10-4 M iso-OMPA, 1% Triton X 100 at 37C. Rinse in doubly distilled water. Dehydrate in glycerine/water mixtures of increasing glycerine content. Store in glycerine or delaminate under dissecting microscope. Delaminated specimens are mounted on gelatinized object glasses, cleared in xylene and coverslipped with Malinol. Specimens stored in glycerine can be studied microscopically. Stained specimens can also be embedded in Paraplast and sections can be studied after counterstaining.     

地霉属真菌和棒状杆菌属菌株协同发酵生产γ-癸内酯

使用有油脂水解活性的地霉属菌株PL-4与有内酯合成能力的棒状杆菌属菌株RS105进行协同发酵转化蓖麻油生产γ-癸内酯,发酵产物用GC/MS（气质联用）方法进行检测,结果显示使用具有油脂降解能力的地震属真菌PL-4协同发酵较单独使用RS105发酵时内酯的产率有明显提高。