Starvation survival of Salmonella enteritidis

Abstract

Washed cells of Salmonella enteritidis harvested from a defined medium during logarithmic growth were subjected to starvation in pH 7 phosphate buffer at 37 C. Viability was measured by slide cultures and plate counts. The survival of cell suspensions equivalent to 1 to 10 mg (dry wt)/ml was influenced by cryptic growth. The rate of cryptic growth, assessed by plate counts, increased with cell density and could not be alleviated by starvation with dialysis. Dialysis of the starving culture did retard the onset of cryptic growth but did not eliminate it, indicating that the major substrates for regrowth were relatively large cellular components. In phosphate buffer, 6.7 homologous heat-killed cells allowed for the doubling of one S. enteritidis cell. Cryptic growth was not observed when cells were starved on the surface of membrane filters or in suspensions equivalent to 20 jig (dry wt)/ml (10' cells/ml). Similar half-life survival times were calculated for both these populations, but the shape of their survival curves differed significantly. These differences were attributed to stress factors encountered during cell preparation and during starvation. The half-life survival time of S. enteritidis on July 15, 2020 by guest

Responses of Marine Bacteria Under Starvation Conditions at a Solid-Water Interface

“…The starvation of a copiotrophic cell can be seen as a sequence of two processes: first a phase of rapid size reduction over a period of a few hours (dwarfing) and then a phase of longterm starvation that has been well documented (2,4,6,13,19,(20)(21)(22).…”

Preservation of Rhizobium viability and symbiotic infectivity by suspension in water

“…109 cells ml-1, were diluted directly in 100 ml of sterile, purified water in 125-ml Wheaton bottles at concentrations ranging from 103 to 107 bacteria ml-'. In two experiments bacteria were grown in MCA medium, harvested, washed twice by centrifugation (13,200 x g for 10 min) with sterile water, and suspended in water at 109 bacteria ml-'. The bacteria were then either stored at this concentration or diluted to 103 bacteria ml-' in different types of purified water.…”

“…Symbols: 0, commercially distilled water; 0, reverse-osmosis deionized water; A, glass-distilled water. utilization of these materials for cryptic growth have been shown to occur under starvation conditions (13). Although some cryptic growth could have taken place in water suspensions of rhizobia, cryptic growth cannot account for the 6.…”

“…manyfold increases in cell number observed for the waterstored rhizobia. Usually, cryptic growth only occurs at cell densities of 105 bacteria ml-' or higher (13), and the death of 50 cells allows for the doubling of one survivor (22). At present, we tentatively suspect that a possible source of growth substances may be the volatile organic components of the air which could have entered the bottles through the Parafilm and dissolved in the water.…”

Bacterial survival in a dilute environment

“…A survey of the literature indicates that the primary focus of research has been on the survival in an aquatic environment of enteric bacteria, especially fecal pathogens (7,21). Al-though this is a logical and important approach, it has not led to an explanation of the persistence of fecal microorganisms in our environment.…”