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山西省异爪蝗属二新种(直翅目:网翅蝗科) 总被引:4,自引:0,他引:4
本文记述在晋南地区采到的异爪蝗属二新种,黑条异爪蝗Euchorthippus nigiliineatus sp.nov.及曲线异爪蝗Eochorthippus sinucarinatus sp.nov. 相似文献
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An extractive fermentation system using immobilized yeast cells was developed to study the ethanol production at high sugar concentrations. Organic acids were used as extracting solvents of ethanol and their toxicity was tested in free and k-carrageenan entrapped cell preparations. Immobilization seems to protect cells against solvent toxicity, when long-chain organic acids, e.g., oleic acid, were used, probably due to steric and diffusional limitations, the free cells not being viable at high oleic acid concentrations. The entrapped cells also present a higher metabolic activity than their free counterparts at high glucose concentrations. A solution of 300 g/L of glucose was totally fermented by the immobilized yeast cells, which when free cannot normally convert more than 200 g/L. In situ recovery of ethanol by oleic acid in a batch immobilized cell system led to higher ethanol productivities and to the fermentation of 400 g/L, when an oleic acid/medium ratio of 5 was used. 相似文献
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Immobilization of Mycobacterium PY1 and Xanthobacter PY2 in alginate and in or on hydroculture has a minor influence on the maximum rate of oxidation of propene and ethane. The apparent K(m) values of the immobilized cells are slightly higher than those of the free cells, indicating the presence of diffusion limitation in the immobilized systems. Both bacterial strains rapidly lose their alkene-oxidizing activity when the water activity is decreased. This decrease in activity is so rapid that most of the activity is lost already when the pores of the pertinent supports are still filled with water. Therefore, it is not possible with this system to study the transition of mass transfer of substrates entirely in the water phase to mass transfer to substrates entirely through the gas phase. 相似文献
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Continuous production of L-phenylalanine by transamination 总被引:2,自引:0,他引:2
L-Phenylalanine was produced continuously from L-as-partate and phenylpyruvate by transaminase from a newly screened Pseudomonas putida strain. The process was carried out with an isolated enzyme in homogeneous phase in an enzyme membrane reactor and with immobilized whole cells in a stirred tank reactor, respectively. Due to the difference in transport resistance, the productivity of the free enzyme in homogeneous phase (72 mmol/L h) was about 3 times higher than the productivity achieved using immobilized cells. However, a better stability of the biocatalyst was observed with immobilized cells. 相似文献
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<正> 啮齿类是在生存竞争中最成功的一类哺乳动物.它们一直受到实验和进化生物学家的特别关注.最近几十年来,有关现生和化石啮齿类的新资料急剧增加.特别是关于啮齿目起源,进化以及它和其它有关门类的系统关系,许多有关学科(如古生物学、胚胎学、比较解剖学、分子生物学、遗传学、细胞发生学等)从各自不同的角度提出了许多意想不到的新见解、新设想,使关于啮齿类的研究呈现出一片生气勃勃的景 相似文献
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Ethoxyzolamide Inhibition of CO(2)-Dependent Photosynthesis in the Cyanobacterium Synechococcus PCC7942 总被引:5,自引:4,他引:1
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Cells of the cyanobacterium, Synechococcus PCC7942, grown under high inorganic carbon (Ci) conditions (1% CO2; pH 8) were found to be photosynthetically dependent on exogenous CO2. This was judged by the fact that they had a similar photosynthetic affinity for CO2 (K0.5[CO2] of 3.4-5.4 micromolar) over the pH range 7 to 9 and that the low photosynthetic affinity for Ci measured in dense cell suspensions was improved by the addition of exogenous carbonic anhydrase (CA). The CA inhibitor, ethoxyzolamide (EZ), was shown to reduce photosynthetic affinity for CO2 in high Ci cells. The addition of 200 micromolar EZ to high Ci cells increased K0.5(CO2) from 4.6 micromolar to more than 155 micromolar at pH 8.0, whereas low Ci cells (grown at 30 microliters CO2 per liter of air) were less sensitive to EZ. EZ inhibition in high and low Ci cells was largely relieved by increasing exogenous Ci up to 100 millimolar. Lipid soluble CA inhibitors such as EZ and chlorazolamide were shown to be the most effective inhibitors of CO2 usage, whereas water soluble CA inhibitors such as methazolamide and acetazolamide had little or no effect. EZ was found to cause a small drop in photosystem II activity, but this level of inhibition was not sufficient to explain the large effect that EZ had on CO2 usage. High Ci cells of Anabaena variabilis M3 and Synechocystis PCC6803 were also found to be sensitive to 200 micromolar EZ. We discuss the possibility that the inhibitory effect of EZ on CO2 usage in high Ci cells of Synechococcus PCC7942 may be due to inhibition of a `CA-like' function associated with the CO2 utilizing Ci pump or due to inhibition of an internal CA activity, thus affecting CO2 supply to ribulose bisphosphate carboxylase-oxygenase. 相似文献