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Fermentation of Insoluble Cellulose by Continuous Cultures of Ruminococcus albus 总被引:6,自引:6,他引:0 下载免费PDF全文
The hydrolysis and fermentation of insoluble cellulose (Avicel) by continuous cultures of Ruminococcus albus 7 was studied. An anaerobic continuous culture apparatus was designed which permitted gas collection, continuous feeding, and wasting at different retention times. The operation of the apparatus was controlled by a personal computer. Cellulose destruction ranged from ca. 30 to 70% for hydraulic retention times of 0.5 to 2.0 days. Carbon recovery in products was 92 to 97%, and the oxidation-reduction ratios ranged from 0.91 to 1.15. The total product yield (biomass not included) per gram of cellulose (expressed as glucose) was 0.83 g g−1, and the ethanol yield was 0.41 g g−1. The product yield was constant, indicating that product formation was growth linked. 相似文献
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We have screened 173 wild caught mice (Mus musculus) from multiple sites in Europe for variation in the activity of 14 enzymes and found 8 different mutants with low enzyme activity; an incidence of 3.69/1000. This compares with the incidence of 3.26/1000 found for low enzyme activity variants in man (Mohrenweiser, 1981).This work was supported by an MRC project grant to G.B. 相似文献
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Spyros D. Kominos Charles E. Copeland Barbara Grosiak Bosko Postic 《Applied microbiology》1972,24(4):567-570
Pseudomonas aeruginosa was isolated from tomatoes, radishes, celery, carrots, endive, cabbage, cucumbers, onions, and lettuce obtained from the kitchen of a general hospital, with tomatoes yielding both highest frequencies of isolation and highest counts. Presence of P. aeruginosa on the hands of kitchen personnel and cutting boards and knives which they used suggests acquisition of the organism through contact with these vegetables. It is estimated that a patient consuming an average portion of tomato salad might ingest as many as 5 x 10(3) colony-forming units of P. aeruginosa. Pyocine types of P. aeruginosa isolated from clinical specimens were frequently identical to those recovered from vegetables, thus implicating tomatoes and other vegetables as an important source and vehicle by which P. aeruginosa colonizes the intestinal tract of patients. 相似文献
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Sylvia K. Green Milton N. Schroth John J. Cho Spyros D. Kominos Vilma B. Vitanza-Jack 《Applied microbiology》1974,28(6):987-991
Pseudomonas aeruginosa was detected in 24% of the soil samples but in only 0.13% of the vegetable samples from various agricultural areas of California. The distribution of pyocin types of soil and vegetable isolates was similar to that of clinical strains, and three of the soil isolates were resistant to carbenicillin. Pseudomonas aeruginosa multiplied in lettuce and bean under conditions of high temperature and high relative humidity (27 C and 80-95% relative humidity) but declined when the temperature and humidity were lowered (16 C, 55-75% relative humidity). The results suggest that soil is a reservior for P. aeruginosa and that the bacterium has the capacity to colonize plants during favorable conditions of temperature and moisture. 相似文献
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During the development of Drosophila melanogaster, individual cells must make choices between a restricted set of possible fates in order to give rise to spatial patterns composed of different types of differential cells. The Notch locus appears to play a central and general role in the regulative events that control the local architecture of the final cellular pattern in several tissues, among them being the central and peripheral nervous systems. 相似文献
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Leonidas DD Maiti TK Samanta A Dasgupta S Pathak T Zographos SE Oikonomakos NG 《Bioorganic & medicinal chemistry》2006,14(17):6055-6064
The binding of a moderate inhibitor, 3'-N-piperidine-4-carboxyl-3'-deoxy-ara-uridine, to ribonuclease A has been studied by X-ray crystallography at 1.7A resolution. Two inhibitor molecules are bound in the central RNA binding cavity of RNase A exploiting interactions with residues from peripheral binding sites rather than from the active site of the enzyme. The uracyl moiety of the first inhibitor molecule occupies the purine-preferring site of RNase A, while the rest of the molecule projects to the solvent. The second inhibitor molecule binds with the carboxyl group at the pyrimidine recognition site and the uridine moiety exploits interactions with RNase A residues Lys66, His119 and Asp121. Comparative structural analysis of the 3'-N-piperidine-4-carboxyl-3'-deoxy-ara-uridine complex with other RNase A-ligand complexes provides a structural explanation of its potency. The crystal structure of the RNase A-3'-N-piperidine-4-carboxyl-3'-deoxy-ara-uridine complex provides evidence of a novel ligand-binding pattern in RNase A for 3'-N-aminonucleosides that was not anticipated by modelling studies, while it also suggests ways to improve the efficiency and selectivity of such compounds to develop pharmaceuticals against pathologies associated with RNase A homologues. 相似文献