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排序方式: 共有1747条查询结果,搜索用时 10 毫秒
1.
Mitsuo Miyazawa Tomohiko Takahashi Kazuki Sakata Isao Horibe 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(7):1006-1011
BACKGROUND: The biotransformation of sesquiterpenoids, which are a large class of naturally occurring compounds, using microorganisms as a biocatalyst to produce useful novel organic compounds was investigated. The biotransformation of sesquiterpenoids, (+)‐aromadendrene ( 1 ), (−)‐alloaromadendrene ( 2 ) and (+)‐ledene ( 3 ) has been investigated using Aspergillus wentii as a biocatalyst. Results: Compound 1 was converted to (−)‐(10S,11S)‐10,13,14‐trihydroxyaromadendrane ( 4 ). Compound 2 was converted to (+)‐(1S,11S)‐1,13‐dihydroxyaromadendrene ( 5 ) and (−)‐5,11‐epoxycadin‐1(10)‐en‐14‐ol ( 6 ). Compound 3 was converted to compound 6 , (+)‐(10R,11S)‐10,13‐dihydroxyaromadendr‐1‐ene ( 7 ) and (+)‐(10S,11S)‐10,13‐dihydroxyaromadendr‐1‐ene ( 8 ). The structure of the metabolic products has been elucidated on the basis of their spectral data. CONCLUSION: Compound 1 gave only one product that was hydroxylated at C‐10, C‐13 and C‐14. By contrast, compounds 2 and 3 gave a number of products, one of which was common. The differences in oxidation of 1–3 are due to the configuration of the C‐1 position. Compounds 4–8 were new compounds. Copyright © 2008 Society of Chemical Industry 相似文献
2.
Evin Van Griethuysen Erwin Flaschel Albert Renken 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1985,35(2):129-138
The pH-dependence of the reaction kinetics of lactase (β-galactosidase) from Aspergillus oryzae in different reaction media is presented in terms of a two-parameter model. The lactase from A. oryzae seems to have replaced the A. niger lactase on the market owing to a better activity/price ratio and may be utilised for lactose hydrolysis in acid as well as in neutral milk products. Its pH optimum is around pH 4.5. However, in the neutral pH-range its activity depended strongly on the salt content of the substrate solution. For example, its activity in whey (pH 6.5) fell to only 30% of its expected activity in a pure lactose solution at the same pH. The whey effect was the same for both soluble and immobilised lactase. The two parameter kinetic model, which included a term for competitive product inhibition gave excellent agreement with experimental data, and may thus be useful for the prediction of reactor performance with this enzyme. 相似文献
3.
Ochratoxin A (OTA) is a secondary metabolite produced by several species of Aspergillus and Penicillium; among them Aspergillus ochraceus and Penicillium verrucosum are two ochratoxigenic species capable of growing in different climates and thus contamination of food crops with OTA can occur worldwide. OTA can be found in a wide range of foods such as cereals, coffee, cocoa, spices, beer, wine, dried vine fruit, grapes and meat products. OTA is toxic to animals, it presents neurotoxic, immunotoxic and nephrotoxic effects. It has been implicated in a human kidney disorder known as Balkan Endemic Nephropathy. This review focuses on the ecophysiology of ochratoxin-producing Aspergillus ochraceus and Penicillium verrucosum, the effect of environmental factors on their germination, mycelial growth, and OTA production. Knowledge of environmental conditions required for sucessive stages of fungal development represent the first step towards preventing mycotoxin formation. Predictive models for different stages of fungal development are presented, which allow prediction of the time before spoilage as a function of the abiotic factors. Finally, the implications of these studies in management of barley, coffee and grapes are described. This can help to identify the critical control points in their production, storage and distribution processes. 相似文献
4.
利用米曲霉对牛乳进行发酵,通过单因子及正交试验以菌丝体干重为指标对其在牛乳中的生长进行了研究.结果表明:接种量为4%,装液量为30mL,摇床转速为180r/min时菌丝体干重可达到最大.此外测得最大菌丝体干重时的蛋白质分解率可达35.6%. 相似文献
5.
Nida Asif Fucheng Lin Lin Li Xueming Zhu Sehar Nawaz 《International journal of molecular sciences》2022,23(15)
Plant diseases cause substantial loss to crops all over the world, reducing the quality and quantity of agricultural goods significantly. One of the world’s most damaging plant diseases, rice blast poses a substantial threat to global food security. Magnaporthe oryzae causes rice blast disease, which challenges world food security by causing substantial damage in rice production annually. Autophagy is an evolutionarily conserved breakdown and recycling system in eukaryotes that regulate homeostasis, stress adaption, and programmed cell death. Recently, new studies found that the autophagy process plays a vital role in the pathogenicity of M. oryzae and the regulation mechanisms are gradually clarified. Here we present a brief summary of the recent advances, concentrating on the new findings of autophagy regulation mechanisms and summarize some autophagy-related techniques in rice blast fungus. This review will help readers to better understand the relationship between autophagy and the virulence of plant pathogenic fungi. 相似文献
6.
7.
Mehmet Karapinar 《International journal of food microbiology》1990,10(3-4):193-199
The antifungal and antiaflatoxigenic activity of anethole and eugenol which are active components of commonly used spices was studied against two strains of Aspergillus parasiticus. Anethole, up to concentration of 400 μg/ml where complete inhibition was observed, delayed growth and reduced mycelial weight but it showed a stimulative effect on the toxin production of both strains. At a concentration of 300 μg/ml, eugenol inhibited the growth of both strains; levels of eugenol below 200 μg/ml enhanced production of aflatoxin particularly by A. parasiticus NRRL 299. 相似文献
8.
Emaeyak N Ukpong C S Odoemena G Ekpo 《Journal of the science of food and agriculture》1994,64(4):449-453
Aspergillus niger (strain UUF9202) significantly reduced the dormancy period and boosted aggregate germination percentage (AGP) in seeds of Tetrapleura tetraptera. A net reduction in mean germination time (MGT) to 12 days and an increase from 0 to 42% AGP were obtained in 32 days. The optimal spore inoculum of the fungus was 8.5 × 10≥10 ml?1 per 100 seeds in 96 h pregermination incubation. The potential of some physical factors in combination with this fungal concentration in enhancing AGP was evaluated. The treatments were as follows: (i) hot water scarification at 30°C, 50°C, 80°C and 100°C plus A niger; and (ii) nicking by decoating at either the micropylar or chalazal ends plus A niger. Micropylar scarification plus A niger gave the highest AGP (94%) followed by chalazal scarification plus A niger (86%) and hot water dip at 80°C + A niger (82%). The control seeds which were soaked in presterilised (by autoclaving at 121°C for 15 min) A niger spore suspension at 30°C gave zero germination. 相似文献
9.
10.
Chih-Yu Cheng Kow-Jen Duan Dey-Chyi Sheu Chi-Tsai Lin Shin-Yi Li 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1996,66(2):135-138
β-Fructofuranosidase (EC 3.2.1.26) in Aspergillus japonicus mycelium was immobilized by entrapment in calcium alginate gel. After immobilization, the enzyme was active over a wider pH range, and had improved thermostability. The total amount of fructooligosaccharides produced by immobilized enzyme was similar to that produced by a free enzyme system. A packed-bed reactor was employed for production of fructooligosaccharides at 42°C using the immobilized enzyme. The reactions were continued for 35 days and only 17% of enzyme activity was lost during this period. 相似文献