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1.
Tarjan Kaliaperumal S. Kumar Sathyanarayana N. Gummadi Anju Chadha 《Journal of industrial microbiology & biotechnology》2010,37(2):159-165
Asymmetric reduction of ethyl-4-chloro-3-oxobutanoate to (S)-ethyl-4-chloro-3-hydroxybutanoate in aqueous medium by resting cells of Candida parapsilosis ATCC 7330 was optimized. The influence of culture parameters (inoculum size, inoculum age and biocatalyst harvest time) and reaction parameters (co-substrate, resting cell, pH and substrate concentrations) on the asymmetric reduction were studied. It was found that these parameters significantly influenced the rate of the asymmetric reduction. Under the optimum conditions, the final concentration of (S)-ethyl-4-chloro-3-hydroxybutanoate, enantiomeric excess and the isolated yield of (S)-ethyl-4-chloro-3-hydroxybutanoate were 1.38 M (230 g/l), >99 and 95%, respectively. The space time yield was 115 mmol/lh, which is significantly higher than other whole cell biocatalysts reported so far. 相似文献
2.
3.
In investigating the response of systems to random input events, dead times in registering these events are met with, as in the case of neuronal behaviour. These situations are studied in terms of product densities making use of the renewal nature of the problem. Different types of cumulative responses of systems are investigated. Some interesting features of a system, which breaks down at a critical value of the cumulative response are analysed. 相似文献
4.
Sexually-mature mungbean (Vigna radiata (L.) Wilczek) plants were efficiently regenerated from cotyledonary node explants. The explants were capable of directly developing multiple shoots on basal media devoid of any growth regulators. The shoot multiplication was influenced by media composition, growth regulators, age of donor seedling and explant type. The explants with both the cotyledons attached to the embryonic axis excised from 4-d-old seedlings, produced the highest number of shoots (5 or 6) in 100% of the cultures within 2 weeks on B5 basal medium (BBM) containing BAP or 2-iP, respectively, (at 5x10–7M) and 3% sucrose. Shoots elongated and developed better using BAP. Increasing micronutrients, carbohydrate and nitrogen levels in the medium above the original formulation of B5 basal medium appeared to be of no benefit for increasing the number of shoots. The shoots were rooted on basal MS medium or MS containing 10–6 of NAA, IAA or IBA. This protocol was found applicable to six other cultivars of mungbean. One hundred rooted shoots were successfully established in soil in the glasshouse, where 90% of them survived. The regenerated plants flowered precociously, but produced normal pods and viable seeds.Abbreviations BAP
6-benzylaminopurine
- KIN
kinetin
- 2-iP
6- — -dimethylallyl aminopurine
- AdS
adenine sulphate
- IAA
indole-3-acetic acid
- IBA
indole-3-butyric acid
- NAA
1-naphthalene acetic acid
- MS
Murashige and Skoog (1962) medium
- B5
Gamborg et al. (1968) medium
- C medium
MS salts + B5 vitamins 相似文献
5.
An osmotically (mannitol) tolerant callus line of Vigna radiata (L.) Wilczek has been isolated from callus cultures grown on modified PC-L2 medium supplemented with increasing concentrations of mannitol. The tolerance was stable and retained after growth in the absence of mannitol selection for 2 months. The growth of the tolerant line, in the presence of mannitol (540 mol m-3) was comparable to that of a sensitive callus line growing in the absence of mannitol. This line not only grew well on media containing up to 720 mol m-3 mannitol, but also required 450 mol m-3 mannitol for its optimal growth. Osmotically tolerant callus also showed increased tolerance to NaCl (0–250 mol m-3) stress as compared to sensitive callus. Accumulation of Na+ was lower, and the level of K+ was more stable in osmotically tolerant than in sensitive calli, when both were exposed to salt. The free proline content of both tolerant and sensitive calli increased on media supplemented with mannitol or NaCl. However, the proline content of sensitive callus was higher than in tolerant callus in the presence of same concentrations of mannitol or NaCl.Abbreviations NAA
-naphthaleneacetic acid
- 2,4-d
2,4-dichlorophenoxyacetic acid
- BAP
6-benzylaminopurine 相似文献
6.
Sequence variation and genetic diversity in the giant panda 总被引:3,自引:0,他引:3
ZHANG YapingOliver A. RyderFAN Zhiyong ZHANG HemingHE TingmeiHE Guangxin ZHANG Anju FEI LisongZHONG Shunlong CHEN HongZHANG Chenglin YANG Minghai ZHU Feibing PENG Zhenxin PU Tianchun CHEN Yucun YAO OMinda GUO Wei 《中国科学:生命科学英文版》1997,40(2):210-216
About 336–444 bp mitochondrial D-loop region and tRNA gene were sequenced for 40 individuals of the giant panda which were
collected from Mabian, Meigu, Yuexi, Baoxing, Pingwu, Qingchuan, Nanping and Baishuijiang, respectively. 9 haplotypes were
found in 21 founders. The results showed that the giant panda has low genetic variations, and that there is no notable genetic
isolation among geographical populations. The ancestor of the living giant panda population perhaps appeared in the late Pleistocene,
and unfortunately, might have suffered bottleneck attacks. Afterwards, its genetic diversity seemed to recover to some extent.
Project supported by the “8.5” Key Project of Chinese Academy of Sciences, the Chairman Foundation of Chinese Academy of Sciences,
K. C. Wang Education Foundation, the Applied Basic Research Foundation of Yunnan, the National Natural Science Foundation
of China, the Special Foundation for Returned Chinese Scientists, and Zoological Society of San Diego. 相似文献
7.
Conditions for plant regeneration from excised shoot tips of Vigna radiata were studied. Complete plants were regenerated directly without an intervening callus phase from shoot tips on basal medium (MS salts+B5vitamins). Regeneration frequency varied with genotype, explant size and growth regulator combinations in the medium. Addition of cytokinins induced a variable amount of callus at the base of the shoot tip, followed by multiple shoot formation. Benzyladenine (BA), kinetin and zeatin at 5×10-6 M each induced multiple shoots in 100% of the explants but the highest number of regenerants per explant (9) was produced with BA. The efficacy of BA for shoot multiplication was not improved when it was supplemented with naphthaleneacetic acid (NAA) or indoleacetic acid (IAA). NAA or adenine sulphate, when applied alone, induced complete plantlets. The growth regulator requirement of explants for the induction of multiple shoots varied with explant size. The shoot tip explants maintained proliferation ability on subculture. None of the treatments was effective in inducing shoot bud differentiation from callus. Regenerated shoots were rooted on MS basal medium and MS supplemented with either IAA or indolebutyric acid. The rooted plants were transferred to the field; 60% subsequently survived and grew.Abbreviations BM
basal medium [MS (Murashige & Skoog 1962) salts+B5 (Gamborg et al. 1968) vitamins]
- BA
6-benzyladenine
- AdS
adenine sulphate
- IAA
indole-3-acetic acid
- NAA-1
naphthaleneacetic acid
- IBA
indolebutyric acid 相似文献
8.
Deactivation of catalase by hydrogen peroxide 总被引:3,自引:0,他引:3
When a mechanism is used to determine possible deactivation kinetics, a certain consistency with the kinetics of the main reaction is found. This result is examined in the light of experimental evidence obtained with bovine liver and Aspergillus catalases. 相似文献
9.
The results of experiments in a fixed-bed reactor and a CSTR containing urease immobilized on a nonporous support and conducted in the absence of diffusional limitations are reported. Kinetic parameters were established by separate batch experiments. The key observation was that the product ammonia attacked the free form of the enzyme and thereby illustrates the importance of mechanism in determining deactivation kinetics. 相似文献
10.
Possible conformations of penicillin G; d and l isomers of ampicillin; α-amino-α-methyl-benzyl penicillins and 3- pyridyl methyl penicillin have been studied by an energy minimization procedure using empirical potential functions. The preferred conformations of these antibiotics have been correlated with their biological activity. The conformational requirement of the antibiotic to be active against Gram-positive and Gram-negative (β-lactamase-negative) bacterial strains seems to be the same. The reduced activity of penicillin G against Gram-negative bacteria has been attributed to its lower ability to permeate the outer membrane. The flexibility of the sidechains of these antibiotics is also shown to be important for the desired biological activity. 相似文献