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41.
J. Power 《Genetics》1967,55(3):557-568
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A study was made of a phenomenon, previously reported, in whichBacillus sphaericus failed to sporulate in the usual peptone media, but would sporulate in these media when grown in association withErwinia atroseptica.Pure culture studies withB. sphaericus indicated that the stimulus driving the cells toward further vegetative growth and the resulting failure of the cells to sporulate was associated with the peptide fraction of peptone media; inhibition of sporulation could be reversed by reduction of the peptone level of the medium or by replacement of the peptone with known amino acids, with known amino acids and short-chain peptides, or with complete hydrolysates of casein.Population and sporulation studies were performed onB. sphaericus cultured inE. atroseptica spent medium and on mixed cultures of the two organisms. A variety of population and sporulation responses were obtained through alteration of the chemical and physical nature of the media byE. atroseptica, cultured alone or in mixed culture withB. sphaericus.It is suggested that removal of pro-vegetative peptides byE. atroseptica is responsible for the enhancement of sporulation observed inB. sphaericus in peptone media.From a thesis submitted to the Graduate School of the University of Maryland, by the senior author, in partial fulfillment of the requirements for the Ph. D. degree. 相似文献
44.
Derek G. Smyth Frederick C. Battaglia Giacomo Meschia 《The Journal of general physiology》1961,44(5):889-898
A simple method is described for the measurement of pH changes in hemoglobin solutions on oxygenation and reduction. Data are presented establishing the absence of a Bohr effect in p-chloromercuribenzoate [PCMB] treated hemoglobin. The influence of a number of sulfhydryl inhibitors on the Bohr effect of a hemoglobin solution is reported and an interpretation based on steric factors in the protein is proposed. 相似文献
45.
Diversifications in the Tube Dilution Test for Antibiotic Sensitivity of Microorganisms 总被引:2,自引:0,他引:2
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The tube dilution method of performing antibiotic sensitivity tests is commonly employed as an accurate method for defining the minimal inhibitory concentration in relation to pathogenic organisms. It is also used as a reference for comparing minimal inhibitory concentrations with the size of the zone of inhibition in the agar diffusion test. Although surveys have shown that there is no standardized method and technique of performing the tube dilution test, it is generally assumed that all of the diversified methods will yield the same results and interpretations. With the assistance of five experts, seven different tube dilution methods were compared; 16 antibiotics, and three organisms for each antibiotic, were used. The conclusions drawn are that, although the accuracy of a single method within its own confines is acknowledged, the minimal inhibitory concentrations and interpretations cannot be interpolated from one laboratory to another where a different technique is employed. The results are frequently discrepant. It is suggested that a uniform method be developed and promulgated for general use. 相似文献
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David J. James Andrew J. Passey Derek J. Barbara Michael Bevan 《Plant cell reports》1989,7(8):658-661
The disamed Ti-binary vector pBIN 6 in Agrobacterium tumefaciens has been used in leaf disc transfomations to produce transgenic apple (Malus pumila Mill.) plants with a nomal phenotype except for a somewhat reduced capacity to root. The presence of the genes for nopaline synthase and neomycin phosphotrans ferase (conferring kanamycin resistance), inserted into the host genome by the vector, was confirmed by Southern blot analysis, the detection of nopaline synthase activity and rooting in the presence of the antibiotic.The nopaline synthase gene continued to be expressed in glasshouse-grown plants several months after removal from in vitro growth conditions. 相似文献
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A Hydrogen-Oxidizing, Fe(III)-Reducing Microorganism from the Great Bay Estuary, New Hampshire 总被引:20,自引:15,他引:5
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A dissimilatory Fe(III)- and Mn(IV)-reducing bacterium was isolated from bottom sediments of the Great Bay estuary, New Hampshire. The isolate was a facultatively anaerobic gram-negative rod which did not appear to fit into any previously described genus. It was temporarily designated strain BrY. BrY grew anaerobically in a defined medium with hydrogen or lactate as the electron donor and Fe(III) as the electron acceptor. BrY required citrate, fumarate, or malate as a carbon source for growth on H2 and Fe(III). With Fe(III) as the sole electron acceptor, BrY metabolized hydrogen to a minimum threshold at least 60-fold lower than the threshold reported for pure cultures of sulfate reducers. This finding supports the hypothesis that when Fe(III) is available, Fe(III) reducers can outcompete sulfate reducers for electron donors. Lactate was incompletely oxidized to acetate and carbon dioxide with Fe(III) as the electron acceptor. Lactate oxidation was also coupled to the reduction of Mn(IV), U(VI), fumarate, thiosulfate, or trimethylamine n-oxide under anaerobic conditions. BrY provides a model for how enzymatic metal reduction by respiratory metal-reducing microorganisms has the potential to contribute to the mobilization of iron and trace metals and to the immobilization of uranium in sediments of Great Bay Estuary. 相似文献
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The sporicidal efficacy of glutaraldehyde (2% w/v) was investigated under various conditions. Numerous factors influenced its activity: method of spore production, inherent spore resistance characteristics, alkalination, storage time and storage temperature. The sporicidal action of 2% alkaline glutaraldehyde at room temperature was compared with that of other aldehydes and commercially available formulations. Cidex (glutaraldehyde) and Sporicidin (glutaraldehyde + phenol full strength) were the most effective, followed by 8% (w/v) formaldehyde and 10% (v/v) Gigasept, a formaldehyde-containing product. Five per cent (v/v) Gigasept and 10% (w/v) glyoxal also had good sporicidal activity, though that of Sporicidin (1 : 16) was poor. No activity was observed with 10% (w/v) butyraldehyde. 相似文献