Starvation In Seawater Research Articles

Cell phenotype changes and oxidative stress response in Vibrio spp. induced into viable but non-culturable (VBNC) state

PurposeAquatic bacteria of the genus Vibrio include animal and human pathogens. The occurrence of Vibrio-related diseases has been associated with the current climate change-driven increase of sea surface temperature. Vibrio spp. can enter into the viable but non-culturable (VBNC) state, as a consequence of starvation in seawater at low temperatures. In such physiological state, Vibrio cells are no longer culturable on standard media agar plates but can resuscitate if incubated at 30 °C prior to plating, retaining virulence. Since limited information is available on regards to this topic, in this work, we characterized the phenotypic changes of four Vibrio spp. strains (one laboratory strain and three environmental isolates) in cold seawater microcosms, investigating the relationship between resuscitation and a hydrogen peroxide-induced oxidative stress.MethodsCell phenotypic changes and the effect of hydrogen peroxide and/or catalase addition to the medium were studied on VBNC and resuscitated cells by flow cytometry in microcosm experiments, paralleled by culturability experiments by plating.ResultsThe cells of all the Vibrio strains changed their phenotype upon the induction of the VBNC state resulting in cell dwarfing and decrease in DNA quantity, losing the ability to grow on solid media. These features were partially or totally reverted when the cells were treated for resuscitation. Hydrogen peroxide at concentrations as low as 0.007 mM prevented resuscitation and a prolonged exposure to hydrogen peroxide at concentrations far under those inhibiting the growth of log-phase cells permanently damaged VBNC cells, which could not be resuscitated. However, the potential of culturability of VBNC cells could be preserved, at least for a part of the population, by plating the cells in the presence of catalase. The study also showed that during the resuscitation process, the cells gradually increased their resistance to hydrogen peroxide.ConclusionsThe timing and mode of induction of the VBNC state, as well as cell resuscitation and response to hydrogen peroxide, differed among Vibrio strains, indicating that induction and resuscitation from dormancy could vary in the context of species belonging to a single genus.

Phenotypic Variations and Molecular Identification of Salmonella enterica Serovar Typhimurium Cells Under Starvation in Seawater

In seawater, enteric bacteria evolve toward a stressed state that is difficult to identify because of major alterations of their phenotype. In this study, we incubated four reference strains of S. enterica serovar Typhimurium in seawater microcosms for 10 months and studied the modifications of their main phenotypic characters. All of the strains lost some key characters used for traditional identification of the Salmonella genus. They became able to produce acetoin, and tryptophane deaminase activity became positive, but they lost the capacity to use rhamnose. We were able to show some modifications of the level of enzymatic profile as well as in their antibiotic susceptibility. The atypical cells of S. enterica serovar Typhimurium were identified by polymerase chain reaction (PCR) methods using the internal transcribed spacer region, and they were confirmed by multiplex PCR after the simultaneous amplification of the phoP, Hin, and H-li genes.

Role de L'Oxygene et Effets des Eaux Residuaires Sur La Survie D'Escherichia Coli en Mer Role of Oxygen and Effects of Sewage on Survival of Escherichia Coli in Seawater

The decrease in the viability of Escherichia coli cells in seawater results from the stress induced by seawater itself as well as their story before their release into the marine environment. Viability in seawater of E. coli cells previously grown anaerobically was after 2 days of starvation in seawater 8.5 times lower than that of cells previously grown aerobically and was 70 times lower for cells starved 6 days in seawater. A previous suspension of cells in sewage decreased 3 to 9 times their subsequent viability in seawater after 2 days of starvation in seawater but viability was no more affected after 6 days of starvation in seawater.

Role de L'Oxygene et Effets des Eaux Residuaires Sur La Survie D'Escherichia Coli en Mer Role of Oxygen and Effects of Sewage on Survival of Escherichia Coli in Seawater

The decrease in the viability of Escherichia coli cells in seawater results from the stress induced by seawater itself as well as their story before their release into the marine environment. Viability in seawater of E. coli cells previously grown anaerobically was after 2 days of starvation in seawater 8.5 times lower than that of cells previously grown aerobically and was 70 times lower for cells starved 6 days in seawater. A previous suspension of cells in sewage decreased 3 to 9 times their subsequent viability in seawater after 2 days of starvation in seawater but viability was no more affected after 6 days of starvation in seawater.

Study of the gelatinolytic activities of Escherichia coli cells before and after starvation in seawater by substrate gel electrophoresis

Previous work has shown that clinical Escherichia coli strains, starved in seawater, are able to present residual growth, with subsequent alterations to their enzymatic activities and metabolism. Gelatinolytic activity of starved cells is of importance because it appears and increases gradually with time. In this work, several forms of gelatinolytic activity were detected by SDS-polyacrylamide gel electrophoresis, differing in molecular masses and appearance, before and after starvation of E. coli cells. The enzymic forms are classified into 4 categories according to the effect of certain inhibitors on the appearance of gelatinolytic activity: a. those whose appearance is inhibited by the chelating factors EDTA, 1, 10-phenanthroline and whose presence is also inhibited by N-ethylmaleimide (metalloproteinases with thiol group active); b. those affected by the presence of chelators, N-ethylmaleimide and Ca 2+ (Ca 2+-dependent metalloproteinases with thiol group active); c. those inhibited by chelators and activated in the presence of Ca 2+ (Ca 2+-dependent metalloproteinases) and d. those whose appearance is independent of the presence of inhibitors used. The forms of gelatinolytic activity of the fourth category coincide with enzyme forms that can also use cascin as substrate in electrophoresis. These data suggest that there are considerable differences in the gelatinolytic pattern of clinical strains of E. coli cells before and after starvation in seawater.

Metabolic and compositional changes in Escherichia coli cells starved in seawater

Thirteen Escherichia coli strains of different biotypes isolated from urine and faeces cultures were studied for metabolic and compositional changes during starvation in seawater at different timepoints. Additionally, the antibiotic susceptibility of the starved E. coli cells was evaluated over time on Mueller-Hinton agar (Bauer-Kirby method). All starved E. coli cells lost β-galactosidase activity gradually with time and acquired the ability to degrade gelatine. Nine of the E. coli strains lost the ability to decarboxylate lysine and seven to acidify melibiose. C 4 esterase, C 8 esterase lipase, leucine arylamidase and C 14 lipase activity increased during starvation, while alkaline and acid phosphatase and phosphoamidase activity decreased. Most of the E. coli strains underwent alterations in their electrophoretic protein pattern. The traditional Bauer & Kirby method was shown to be inadequate for testing antibiotic susceptibility of starved strains.

Correlation between changes in surface hydrophobicity and interaction of Streptococcus pyogenes with human polymorphonuclear leukocytes after prolonged starvation in sea water

The aim of this research was to evaluate the persistence of virulence characteristics of Streptococcus pyogenes cells after prolonged starvation in sea water. Studies were carried out on changes in viability, alterations in the chemical composition and surface hydrophobicity and the interaction of S. pyogenes with human polymorphonuclear leukocytes (PMN) after starvation. Results showed that surface hydrophobicity decreased progressively starting after three days of starvation and was correlated with the decrease in total carbohydrate, lipid and protein content. These values correlated with a better interaction of S. pyogenes cells with the PMN, as shown by a chemiluminescence increase that reached a peak after 32 days of starvation. Furthermore, bacterial cells became more easily phagocytized and killed by human PMN.

Variations in the Oxygen Uptake, Reduced Weight and Metabolic Rate of Starving Sporocysts of Microphallus pygmaeus (Levinsen, 1881) (Trematoda: Microphallidae)

The variations in the oxygen uptake, reduced weight, metabolic rate and the number of contained, fully formed, healthy, autolysed or dead metacercariae, recorded during starvation in sea water, in vitro, suggest that first mainly stored carbohydrates, then mainly lipids and, in the final stages of starvation, mainly proteins are broken down and metabolised, by the sporocysts of Microphallus pygmaeus.

Iron Metabolism in Mytilus Edulis 1. Variation in Total Content and Distribution

The iron content of fresh Mytilus edulis L. from Southampton is usually 20–40 μg/g wet weight after the animals have eliminated their gut contents. In spring some animals have much higher iron contents, sometimes in excess of 100 μg/g. The much higher values reported by some authors are probably erroneous.Prolonged starvation in sea water of low iron content will not reduce the mean iron content of the animals below 20–25 μg/g. This represents a permanent store. Higher values are produced by a temporary store that is fairly rapidly lost on starvation.The highest iron concentrations are usually in the digestive gland, which contains the major part of the temporary store, much of which can be regarded as particles being subjected to the digestive processes.Only iron in the temporary store could be demonstrated by histochemical techniques.INTRODUCTIONThe trace element metabolism of Vertebrates, particularly Mammals has been reviewed by Bothwell & Finch (1962); and Vinogradov (1953) has made a comprehensive review of the elementary chemical composition of living organisms. With notable exceptions, such as the copper in haemocyanin, the trace elements discovered in many invertebrates have no known function. The reported values for many elements differ considerably, depending on the author and the techniques used. In general, despite a number of errors in the values quoted, Vinogradov's data establish at least the order of magnitude of many elements in a variety of animals. Some of these elements occur in greater amounts than would be expected if they were not of metabolic significance. One example, namely iron in Mytilus edulis L., was selected for investigation.