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SURVIVAL OF SALMONELLA SPECIES IN RIVER WATER.
Citation:
Santo Domingo*, J W., S M. Harmon*, AND J Bennett*. SURVIVAL OF SALMONELLA SPECIES IN RIVER WATER. Balows, A. (ed.), CURRENT MICROBIOLOGY. Springer-Verlag, New York, NY, 40(6):409-417, (2000).
Description:
The survival of four Salmonella strains in river water microcosms was monitored using culturing techniques, direct counts, whole cell hybridization, scanning electron microscopy, and resuscitation techniques via the direct viable count method and flow cytrometry. Plate counts of bacteria resuspended in filtered and untreated river water decreased several orders of magnitude within the first week of incubation, while they did not decrease as rapidly in autoclaved water. In situ hybridization studies suggested a rapid decrease in ribosomal content, as determined by the drastic decrease in the number of detectable cells after 72 h. In contrast, direct counts remained relatively constant during 45 days in all microcosms. While after 31 days the culturable counts of two bacterial strains in filtered water represented approximately 0.0015 of the total counts, direct viable counts and resuscitation studies using a dilution series suggested that the number of viable bacterial was at least 4 orders of magnitude higher. Additionally, notable changes in forward scatter and in nucleic acid content were observed only after 4 h of nutrient amendments using flow cytometry. However, cells from the resuscitation experiments did not grow on solid media unless cell-free supernant from biable cultures was added during the resuscitation period. The results in this study suggest the presence of an not immediately culturable status in Salmonella.