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Cell Division Mutations in the Blue-Green Bacterium Agmenellum quadruplicatum Strain BG1: a Comparison of the Cell Wall 总被引:2,自引:2,他引:0 下载免费PDF全文
The peptidoglycan from two types of filamentous cell division mutants of Agmenellum quadruplicatum strain BG1 has been compared to that of the parent organism. Small variations in the total peptidoglycan composition on a dry-weight basis were found in the mutants. The reduced level of peptidoglycan in the serpentine mutant is consistent with a general decrease in the ratio of surface area to volume as compared to the parent organism. The increased peptidoglycan content in the septate mutant confirms previous ultrastructural observations of the greatly enlarged peptidoglycan septum between adjacent cells. A comparison of peptidoglycan composition and cross-linking in the two types of filamentous mutants of A. quadruplicatum and in drug-induced phenocopies suggests that structural alterations of the peptidoglycan are not involved in the apparent impairments of cellular division. Furthermore, data concerning the relative susceptibilities of the parent and mutants to antibiotics indicate that neither mutant exhibits a gross alteration of permeability. 相似文献
948.
Loring S. H.; Drazen J. M.; Snapper J. R.; Ingram R. H. Jr 《Journal of applied physiology》1978,45(1):40-44
949.
Magnesium limitation and its role in apparent toxicity of ethanol during yeast fermentation 总被引:1,自引:0,他引:1
The rate of ethanol production per milligram of cell protein begins to decline in the early stage of batch fermentation before high concentrations of ethanol have accumulated. In yeast extract-peptone medium (20% glucose), this initial decline appears to be related to growth and to result in part from a nutrient deficiency. The addition of yeast extract, peptone, and ashed preparations of these restored the ability of glucose-reconstituted medium (in which cells had been previously grown) to support vigorous growth. Magnesium was identified as the active component. Supplementing fermentations with 0.5 mM magnesium prolonged exponential growth, resulting in increased yeast cell mass. The addition of magnesium also reduced the decline in fermentative activity (micromoles of CO2 evolved per hour per milligram of protein) during the completion of batch fermentations. These two effects reduced the time required for the conversion of 20% glucose into ethanol by 1/3 with no measurable loss in ethanol yield (98% of theoretical maximum yield). It is possible that some of the reported beneficial effects of complex nutrients (soy flour and yeast extract) for ethanol production also result from the correction of a simple inorganic ion deficiency, such as magnesium. 相似文献
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Fischerella ambigua is a branching blue-green alga, the filamentous nature of which is maintained almost entirely by sheath material. Cell division in this organism most closely resembles the septal division found in most unicellular organisms. In all filamentous blue-green algae previously examined with the electron microscope, cell division has resulted from the imagination of the plasma membrane and inner wall layer only; both the middle wall and the outer wall layers remain continuous throughout the length of the filament. In Fischerella, by contrast, the plasma membrane and the inner wall layer invaginate to produce initially 2 cells. However, the middle wall layer, outer wall layer, and sheath also invaginate to separate the daughter cells. The sheath alone remains continuous throughout the length of the filament. 相似文献