性激素三孢酸在类胡萝卜素生产菌三孢布拉氏霉中的合成代谢研究进展

类胡萝卜素是重要的精细化学品,三孢布拉氏霉是发酵法生产类胡萝卜素的常用菌种。近年来研究者对影响三孢布拉氏霉类胡萝卜素产量的影响因素做了大量的研究,结果显示三孢酸是最重要的影响因子之一。本文根据国内外研究进展,从发酵法生产类胡萝卜素的研究现状、三孢酸类化合物的结构及其生理功能、三孢酸合成途径研究及三孢酸合成途径中的分子机制等几个方面做了综述报告。     

吡啶类化合物对三孢布拉氏霉菌代谢途径的影响

利用β-胡萝卜素高产菌株三孢布拉氏霉菌(Blakeslea trispora)发酵生产番茄红素过程中,可通过突变菌株或中途加入阻断剂的方法,将代谢控制在番茄红素水平.主要考察了吡啶衍生物如2,6-二甲基吡啶、2,5-二甲基吡啶、2-氨基-6-甲基吡啶及烟草废弃物(主要成分为3-吡啶基衍生物)对三孢布拉氏霉菌代谢途径的影响.结果表明1.0g/L的2,6-二甲基吡啶阻断效果最好,大量积累番茄红素,几乎无β-胡萝卜素生成;加入的烟草废弃物浓度为15g/L时,有少量β-胡萝卜素生成,番茄红素含量较前者提高58%,达到1 090.03mg/L.     

Carotenoid pattern in Blakeslea trispora grown on oil‐enriched substrates with regard to triacylglycerol species accumulation

The carotenoid pattern in Blakeslea trispora grown on oil‐enriched substrates was investigated with regard to triacylglycerol (TAG) species accumulation, to assess the interrelationship between these two processes. Analysis of individual carotenoids and TAG was carried out by HPLC. β‐Carotene production was at the expense of lycopene and γ‐carotene formation in cells grown on crude olive pomace oil (COPO) and crude soybean oil (CSO) at two levels of addition (10.0 and 30.0 g/L culture medium). A shift to γ‐carotene synthesis was observed at increased oil level. Cellular lipids produced at the low COPO or CSO levels contained more unsaturated TAG compared with those obtained on glucose as the sole carbon source. With regard to the typical soybean or olive oil TAG profile, cellular TAG had profiles dependent on the type and the amount of the co‐substrates used. In the presence of CSO, the cellular TAG profile was similar to that of the respective oil for both levels of addition. A notable desaturase activity was observed only in the presence of low COPO addition. The present study can serve as a basis for a better understanding of TAG accumulation with regard to β‐carotene production in oil‐enriched substrates.     

Optimization of the production of β‐carotene from molasses by Blakeslea trispora: a statistical approach

The effect of pretreatment of molasses, nitrogen sources, natural oils, fatty acids, antioxidant, precursors, and mixtures of the above substances on β‐carotene production by Blakeslea trispora in shake flask culture was investigated. Also, a central composite design was employed to determine the maximum β‐carotene concentration at optimum values for the process variables (linoleic acid, kerosene, antioxidant). The highest concentration of the carotenoid pigment was obtained in molasses solution treated with invertase. Corn steep liquor and yeast extract at concentrations of 5.0% and 0.5% (w/v), respectively, increased slightly the concentration of β‐carotene, while the natural oils, fatty acids, and precursors (except kerosene) did not improve the production of pigment when they were added separately to the medium. On the other hand, the mixture of linoleic acid, kerosene and antioxidant increased significantly the concentration of β‐carotene. The fit of the model was found to be good. Linoleic acid, kerosene and antioxidant had a strong linear effect on β‐carotene concentration. The concentration of β‐carotene was significantly affected by linoleic acid–antioxidant and kerosene–antioxidant interactions as well as by the negative quadratic effects of these variables. The interaction between linoleic acid–kerosene had no significant linear effect. Maximum β‐carotene concentration (790.0 mg dm^?3) was obtained in culture grown in molasses solution supplemented with linoleic acid (30.74 g dm^?3), kerosene (27.79 g dm^?3) and antioxidant (10.22 g dm^?3). © 2002 Society of Chemical Industry     

Effect of mycelial morphology on bioreactor performance and avermectin production of Streptomyces avermitilis in submerged cultivations

Factors affecting the morphology of Streptomyces avermitilis and avermectin production in submerged cultivation, including nitrogen sources, inoculum level and DO (dissolved oxygen) tension in the broth were investigated in a 50-L bioreactor. It was found that a combination of soybean meal and yeast meal as nitrogen sources and 4.3% inoculum led to pellet formation, and the pellet morphology facilitated to maintain DO > 20% in the early stage of fermentation. With the aid of image analysis tools, area and density of pellets in different batches were calculated. Results show that higher dissolved oxygen tension was favorable for pellet formation and avermectin production.     

The Hagen-Poiseuille pump for parallel fed-batch cultivations in microbioreactors

We developed and applied a micropump for liquid flows of 0-150 nL/min. The operating principle of this pump is based on the Hagen-Poiseuille law. The main advantages of this pump are that an accurate continuous flow rate can be achieved, it is cheap to manufacture, easy to parallelize and easy to integrate in microtiter plates. Experiments at different flow rates showed that the flow rate remained stable in time and the measured flow rates corresponded very well to the Hagen-Poiseuille law. The applicability of the pump for reproducible feeding of microbioreactors was shown in a fed-batch system with a simple chemical reaction. Thereby the Hagen-Poiseuille pump was connected to a microbioreactor with a working volume of 100 μL. The microreactor was filled with a H₂SO₄ solution which was fed with a Na₂CO₃ solution at a constant rate, while measuring the CO₂ release on-line. This resulted in a stable CO₂ production rate. Subsequently, the pump was successful applied to carry out anaerobic fed-batch fermentations of Saccharomyces cerevisiae in the microreactor system for periods up to 20 h.     

The intake of carotenoids in Denmark

To estimate the intake of carotenoids in the Danish population Danish fruits and vegetables were screened with an HPLC method consisting of extraction with ethanol:tetrahydrofuran, separation by reversed phase HPLC with the mobile phase acetonitril:methanol:dichlormethan, triethylamin, BHT and detection at 450 nm. Food intakes were estimated by the national dietary surveys (1995) from 7 days' food registration (n = 1837 adults), which allows the whole diet to be described by the mean intake and intake distribution of 207 raw or semiprepared foods. By multiplication with the mean content in the foods the mean intake and intake distribution of the carotenoids were calculated. Carrots and tomatoes have both high contents of carotenoids (8,450 μg/100 g α‐ + β‐carotene and 4,790 μg/100 g lycopene, respectively) and high intakes (19 and 15 g/day, respectively) and were responsible for 47% and 32%, respectively, of the mean intake of carotenoids of 4.8 mg/day. A median value of 4.1 mg/day was found indicating skewed intake distributions. The difference between men and women was 0.4 mg/day (p < 0.0065). Only four carotenoids, α‐carotene, β‐carotene, lutein and lycopene, contributed significantly to the intake. Women had a 6 g/day higher intake of carrots than men (p < 0.0001), which explains the 0.4 mg/day difference in the intake between men and women, and the 25th percentile was well over zero (5.0 g/day for men and 5.9 g/day for women) indicating that almost everybody consumed at least some carrots.     

玻璃基板化学镀工艺

1　前言近年来计算机等外部记录装置多数使用固定磁盘装置。磁盘上搭载的磁盘基板 ,过去是在非磁性铝板上化学镀非磁性的Ｎｉ Ｐ合金镀层 ,随着磁盘的高记录密度化和小型薄板化 ,希望采用容易小型薄板化且可获得高平滑性的玻璃基板 ,然而玻璃基板上难以形成附着性和平滑性十分优良的化学镀Ｎｉ Ｐ合金镀层。为了改善镀层附着性和平滑性 ,采用ＳｎＣｌ2 溶液敏化处理 ,但是敏化液中Ｓｎ2 + 容易氧化成Ｓｎ4 + ,导致敏化液混浊 ,降低敏化液使用寿命 ,还由于锡盐的影响 ,容易发生镀层不均、镀层凹痕或者无镀层析出等缺陷。鉴于上述状况 ,本文就…     

非金属基体的导电化处理

为了在非金属上获得金属镀层,非金属上必须先获得导电层.开发出了经过添加树脂得到的改性石墨乳涂料以及在其上的电镀铜工艺,用以取代胶体钯法.研究结果证明,改性石墨乳使得其与非金属之间的结合力得到了充分的保证,具有一定的强度,并且改性石墨乳具有可操作性,成本低廉,来源广泛等优点,将会在非金属表面导电化处理中有广泛的应用.     

铜基上化学镀锡

研究了化学镀锡工艺,结果表明,随着镀液温度的升高,化学镀锡的沉积速率提高,当温度达到８０℃时,沉积速率最高;若继续升高镀液温度,沉积速率却降低。此外,化学镀锡的沉积速率随化学镀时间的延长而增加。镀液稳定可靠,采用本工艺可得可光亮的锡镀层。     

Antioxidant activity of β-carotene-related carotenoids in solution

The effect of the antioxidant activity of β-carotene and related carotenoids on the free radical-oxidation of methyl linoleate in solution was examined by measuring the production of methyl linoleate hydroperoxides. Canthaxanthin and astaxanthin which possess oxo groups at the 4 and 4′-positions in the β-inonone ring retarded the hydroperoxide formation more efficiently than β-carotene and zeaxanthin which possess no oxo groups. The rates of autocatalytic oxidation of canthaxanthin and astaxanthin were also slower than those of β-carotene and zeaxanthin. These results suggest that canthaxanthin and astaxanthin are more effective antioxidants than β-carotene by stabilizing the trapped radicals.     

TFT-LCD玻璃基板制造过程中的几点体会

TFT-LCD玻璃基板是显示产业链的关键上游材料。以中小世代溢流下拉法生产TFT-LCD玻璃基板为例,重点阐述了半成品生产的关键管控理念:质量守恒、能量守恒、电量守恒以及成型稳定的重要性,阐述了成品生产中基础管理工作的重要性,洁净管理和二次污染对质量的影响。     

Substrate effect on oxygen reduction electrocatalysis

The oxygen reduction reaction (ORR) was investigated on carbon (XC-72) supported platinum nanoparticles, generated via the carbonyl chemical route and on oxide composites supported platinum generated via the UV-photo-deposition technique in sulfuric acid medium. The behavior of Pt/C was examined using a careful dosing of the catalyst loading spanning the range from 4.3 to 131 μg cm⁻². The ORR electrochemical response of Pt/C (in line with recent literature data) is put into contrast with the Pt/oxide-composite systems. Our results point out that it is possible to use smaller amounts of catalyst for the ORR when platinum atoms interact with the oxide (anatase) surface of the substrate composite. Evidence of the incipient metal-substrate interaction is discussed in the light of the results of XRD experiments.