Effect of previous growth conditions on the starvation-survival of Escherichia coli in seawater

Abstract

The starvation-survival of Escherichia coli in seawater was assessed by plate and epifluorescence counts, 3H-label decrease, cellular DNA concentrations, and metabolic activities. These assays were performed on two types of populations, adapted and non-adapted to seawater. The number of viable cells in the adapted population remained constant throughout starvation-survival in sterile seawater. In contrast, a significant decrease in the ability of the non-adapted E. coli to form colonies on plates following starvation-survival in sterile seawater was observed. However, this drop in viable counts was not mirrored by the epifluorescence counts and 3H-label, which did not show major changes for either population during the experiments, indicating maintenance of the number of cells. In addition, a significant increase in and subsequent maintenance of DNA content and thymidine incorporation was observed for both populations during starvation-survival in sterile seawater. The changes in cell-attached exoproteolytic activity and electron transport system activity showed that adapted and non-adapted E. coli cells maintain their metabolic potential. Cell-free exoproteolytic activity was drastically reduced in both populations. Adapted cells showed higher electron transport system activity and thymidine incorporation than non-adapted cells at the onset of starvation-survival. The effect of previous adaptation on E. coli starvation-survival, as assessed by plate counts and 3H-label decrease, was also observed in raw seawater. It seems from these data that the biological potential of E. coli cells suspended in sterile seawater has not been switched off or impaired seriously.

The effects of temperature, water activity and pH on the growth of Aeromonas hydrophila and on its subsequent survival in microcosm water

“…However, it is likely that interpretation of water viability studies depends, to a large extent, upon the specific conditions during and even before the actual experiments, including the bacterial strains used and their growth history (Rozen and Belkin 2001). In several studies it was found that the survival ability of enteric bacteria depends on their history prior to their arrival into the marine environment (Munro et al 1987;Gauthier et al 1989;Gauthier et al 1992;Garcia-Lara et al 1993). It is an obvious fact that their previous growth history plays a major part in pre-adaptation of the cells (Munro et al 1994;Rozen and Belkin 2001).…”

“…Indeed, reported survival times for bacterial populations exposed to the aquatic environment vary considerably as a consequence of previous growth (Rozen et Belkin 2001). In several studies, it was found that the survival ability of bacteria depends on their history preceding the aquatic contact (Munro et al 1987;Gauthier et al 1989;Gauthier et al 1992;Garcia-Lara et al 1993). For example, Garcia-Lara et al (1993) have shown that pre-adaptation by growth in an artificial seawater medium supplemented with complex organics (tryptone, peptone and yeast extract) led to greater survival rates in seawater.…”

“…In several studies, it was found that the survival ability of bacteria depends on their history preceding the aquatic contact (Munro et al 1987;Gauthier et al 1989;Gauthier et al 1992;Garcia-Lara et al 1993). For example, Garcia-Lara et al (1993) have shown that pre-adaptation by growth in an artificial seawater medium supplemented with complex organics (tryptone, peptone and yeast extract) led to greater survival rates in seawater. Munro et al (1987) demonstrated the same phenomenon using four enteric bacteria (Shigella dysenteriae, Escherichia coli, Klebsiella pneumoniae and Salmonella serotype Typhimurium).…”

Effects of High Pressure on Survival and Metabolic Activity of Lactobacillus plantarum TMW1.460

“…The staining of cells with tetrazolium salts was proposed as a rapid method for determination of cell viability (9,43,45). Tetrazolium reduction to formazan by lactobacilli depends on the activity of NADH-dependent enzymes, such as NADH oxidase or peroxidase activities, or specific NADH dehydrogenases that are present in LAB (4,20,24,30,37,39).…”

Scientific Opinion on the minimum hygiene criteria to be applied to clean seawater and on the public health risks and hygiene criteria for bottled seawater intended for domestic use

“…Survival depends on factors such as amount of solar radiation, water temperature, presence of organic mater and adequate nutrients, presence of bacteriophages, autochthonous microbiota, protozoa predation, osmotic stress, etc. Adapted cells also show more survival capacity (Garcialara et al, 1993), and there is a genetic response of cells to the environmental challenges mentioned above (salinity, starvation, pH etc. ), which is mostly mediated by the rpoS regulon (Rozen and Belkin, 2001).…”