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11.
12.
Bernd Günzel Sems Yonsel Wolf-Dieter Deckwer 《Applied microbiology and biotechnology》1991,36(3):289-294
Summary The conversion of glycerol to 1,3-propanediol (PD) by Clostridium butyricum DSM 5431 was studied in anaerobic culture. Growth and product formation were optimal at pH = 7.0 and T = 35° C, while aeration rate and stirrer speed were found to have no significant influence. As increasing amounts of initial glycerol led to inhibition of growth, cultivations were done in fed-batch operation. Comparative cultivations were carried out in an air-lift (ALR) and a stirred-tank reactor (STR) having equal working volumes (V
L = 30 l) and no difference in product formation was found. The process was scaled up to reactor sizes of 1.2 m3 (ALR) and 2.0 m3 (STR). The same results were obtained irrespective of reactor volume as well as reactor type (STR/ALR). PD concentrations of approximately 50–58 g·l–1 and overall productivities of 2.3–2.9 g·l–1 ·h–1 could be reached.
Offprint requests to: W.-D. Deckwer 相似文献
13.
Bernd Blechschmidt Petra Borneleit Hans-Peter Kleber 《Applied microbiology and biotechnology》1991,36(3):364-368
Summary The formation and localization of the -lactamase of Acinetobacter calcoaceticus CCM 5593 is strongly affected by cultivation and induction conditions. Optimal parameters for enzyme yield are cultivation on minimal salts medium with acetate (10 g·1–1) as carbon source and addition of yeast extract (5–10 g·l–1), induction by cefotaxime (50g·ml–1) immediately after inoculation and growth for 24 h at 25° C. The strain forms a basal level of -lactamase constitutively [70 units (U)·g–1]. Nearly all of this was found to be cell-bound. However, -lactamase activity additionally produced after induction (up to 500 U·g–1 wet bacteria) was located in the culture medium (up to 96%). This unusual localization is a special feature of A. calcoaceticus and is not attributed to cell lysis.
Offprint requests to: P. Borneleit 相似文献
14.
15.
In order to investigate the role of peroxidase-mediated metabolic activation in the mechanism of carcinogenicity of diethylstilbestrol (DES), a series of 14C-labelled analogs of DES was synthesized and their binding to DNA upon oxidation by peroxidases from horseradish or mouse uterus was studied in vitro. The compounds chosen for this study were the erythro and threo form of hexestrol (HES), the E,E- and Z,Z-isomer of dienestrol (DIES) and the mono- and dimethyl ether of DES.
Non-extractable binding to DNA was observed for all compounds with at least one free hydroxyl group independent of the stilbene structure. The extent of binding was highest for the HES isomers and for E,E-DIES, whereas Z,Z-DIES and the monomethyl ether were bound to about the extent of DES. These findings imply that the formation of a phenoxy free radical is sufficient for non-extractable DNA binding and the stilbene structure is not required for peroxidase-mediated activation of DES. 相似文献
16.
Bernd Heinrich Stephen L. Buchmann 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1986,156(4):557-562
Summary The carpenter beesXylocopa varipuncta maintain thoracic temperatures of 33.0°C to 46.5°C during continuous free flight from 12°C to 40°C. Since the thoracic temperature excess is not constant (decreasing from 24°C at low air temperatures to 6°C at high) the bees are thermoregulating. We document physiological transfer of relatively large amounts of heat to the abdomen and to the head during pre-flight warm-up and during artificial thoracic heating. Most of the temperature increase of the head is due to passive conduction, while that of the abdomen is due to active physiological heat transfer despite a series of convolutions of the aorta in the petiole that anatomically conform to a counter-current heat exchanger. Although the thermoregulatory mechanisms during flight are far from clarified, our data suggest that thermoregulation involves a strong reliance on active convective cooling through increased flight speed. 相似文献
17.
Passive Avoidance Training Increases Fucokinase Activity in Right Forebrain Base of Day-Old Chicks 总被引:3,自引:3,他引:0
Fucokinase (EC 2.7.1.52) activity was estimated in supernatants of homogenate from day-old chick forebrain. Enzyme kinetic studies gave a Km of 4.5 X 10(-6) M and Vmax of 3.72 nmol fucose converted into fucose-1-phosphate/mg prot/h. The pH optimum was 7.5. The enzyme is thus considerably more active than was reported for other species and tissues. There were no differences in enzyme activity between the four forebrain regions studied. One hour after chicks were trained on a one-trial passive avoidance learning paradigm, enzyme activity in the right forebrain base increased 14% over control values (p less than 0.02). The 11.3% increase in activity in the left forebrain base and 10.3% increase in the left roof were not statistically significant. The relationship of this change to the increased fucose incorporation into glycoproteins known to occur over a similar time period and the significance of the lateralization of the increase are discussed. 相似文献
18.
Klaus Hallermayer Christine Harmening Herbert Merz Bernd Hamprecht 《Journal of neurochemistry》1983,41(6):1761-1765
The benozomorphan derivative (-)-2-[2-(p-bromoacetamidophenyl)ethyl]-5,9 alpha-dimethyl-2'-hydroxy-6,7-benzomorphan (BAB), capable of reacting with nucleophilic groups, acts on neuroblastoma X glioma hybrid cells as a potent, irreversible opiate agonist. Its potency in inhibiting the increase in cellular cyclic AMP, evoked by prostaglandin E1, is comparable to that of Leu-enkephalin. This also applies to its capacity to compete with [3H]D-Ala2-Met-enkephalinamide ([3H]DAEA) in binding on cell membrane preparations. The comparatively lower potency of (-)-2-[2-(p-acetamidophenyl)-ethyl]-5,9 alpha-dimethly-2'-hydroxy-5,7-benzomorphan (AB), which differs from BAB in the substitution of the bromoacetamido group by an acetamido group, is of the same order of magnitude as that of morphine. The covalent interaction of BAB with the opiate receptors is deduced from the observations that (1) it is not possible to wash away this compound from the receptors, (2) the potency of BAB in inhibiting the specific binding of [3H]DAEA increases with prolonged preincubation time, and (3) AB behaves as a reversible agonist. 相似文献
19.
Summary The occurrence of the allele Pr showing an unexpected atypical isozyme band pattern in a Caucasian family is reported. 相似文献
20.
The aims, content, and organisatory structure of a proposed interdisciplinary ecosystem research project in the Wadden Sea
of Schleswig-Holstein (W. Germany) are briefly presented. The project will include research on both fundamental as well as
applied aspects of the Wadden Sea ecosystems and their interaction with local human activities. In contrast to most of the
other completed or currently running ecosystem research projects on tidal coasts, a considerable part of the scientific work
will also deal with aspects of ecosystem management and protection of the various marine and semiterrestrial habitats of the
Wadden Sea. Considerable attention is paid to theoretical and methodological aspects of research on ecosystems and landscape
units. In particular, the adoption of a hierarchical view of complex biological and environmental systems is recommended.
Presented at the VI International Wadden Sea Symposium (Biologische Anstalt Helgoland, Wattenmeerstation Sylt, D-2282 List,
FRG, 1–4 November 1988) 相似文献