Evaluation of Factors Affecting Survival of Escherichia coli in Sea Water: V. Studies with Heat- and Filter-sterilized Sea Water1

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RESUMO

The bactericidal action of sea water was measured as the difference in survival of cells of Escherichia coli in untreated and autoclaved portions of water samples. The beneficial effect of sterilization by heat on the survival of E. coli in sea water varied with season and was most marked during summer months, however, the magnitude of the effect differed greatly from sample to sample. The more obvious and commonly suggested explanations for the bactericidal action of sea water were tested experimentally. The pH and salinity of sea water were changed by autoclaving, but the direction of the former was detrimental rather than beneficial and the significance of the latter was not clarified. The survival of cells of E. coli in filtered portions of some water samples was greater than that in untreated portions and equal to that in autoclaved portions, indicating that predators and competitors removed by filtration had contributed significantly to the rapid death of the bacterium in the untreated water. However, in the majority of samples tested, survival of E. coli in autoclaved water was considerably greater than survival in filtered water.

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