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M Mergeay

Publications and source records attributed to M Mergeay.

71 records · Page 4Linked to original sources
PubMed1976

DNA uptake by Streptomyces species.

Uptake of homologous and heterologous radioactively labelled DNA was studied in ten Streptomyces species. Among these, S. kasugaensis and S. virginiae were shown to take up 0.5-2.0% of the supplied donor DNA at a well-defined point in their growth cycle. The heterologous donor DNA taken up retained its original buoyant density in CsCl gradients. Other strains either extensively degraded the donor DNA or showed poor uptake efficiency.

Biological Transport↗
PubMedDate not supplied

Space flight effects on bacterial physiology.

The study of bacterial behavior under space flight conditions is highly important for the early detection of changes in bacterial communities and bacteria with medical, environmental, or life support consequences for survival of the crew in closed space environments. Although many species of prokaryotes have been studied in ground simulation facilities or have been flown in space flights, at present only few hard research data are available to predict the effects of cosmic radiation, microgravity, vibration and hypervelocity on microbial behavior in space flight. The results that are available tend to be fragmentary and often lack a classical, controlled experimental context to interpret them. Thus, many basic questions concerning the effects of space on microbial behavior have yet to be resolved.

Bacteria↗
PubMedDate not supplied

Physiological changes induced in four bacterial strains following oxidative stress.

In order to study the behaviour and resistance of bacteria under extreme conditions, physiological changes associated with oxidative stress were monitored using flow cytometry. The study was conducted to assess the maintenance of membrane integrity and potential as well as the esterase activity, the intracellular pH and the production of superoxide anions in four bacterial strains (Ralstonia metallidurans, Escherichia coli, Shewanella oneidensis and Deinococcus radiodurans). The strains were chosen for their potential usefulness in bioremediation. Suspensions of R. metallidurans, E. coli, S. oneidensis and D. radiodurans were submitted to 1 h oxidative stress (H2O2 at various concentrations from 0 to 880 mM). Cell membrane permeability (propidium iodide) and potential (rhodamine-123, 3,3'-dihexyloxacarbocyanine iodide), intracellular esterase activity (fluorescein diacetate), intracellular reactive oxygen species concentration (hydroethidine) and intracellular pH (carboxyflurorescein diacetate succinimidyl ester (5(6)) were monitored to evaluate the physiological state and the overall fitness of individual bacterial cells under oxidative stress. The four bacterial strains exhibited varying sensitivities towards H2O2. However, for all bacterial strains, some physiological damage could already be observed from 13.25 mM H2O2 onwards, in particular with regard to their membrane permeability. Depending on the bacterial strains, moderate to high physiological damage could be observed between 13.25 mM and 220 mM H2O2. Membrane potential, esterase activity, intracellular pH and production of superoxide anion production were considerably modified at high H2O2 concentrations in all four strains. In conclusion, we show that a range of significant physiological alterations occurs when bacteria are challenged with H2O2 and fluorescent staining methods coupled with flow cytometry are useful for monitoring the changes induced not only by oxidative stress but also by other stresses like temperature, radiation, pressure, pH, etc....

Bacteria↗