The reaction of radicals induced in Escherichia coli B/r by γ-rays with cysteamine and with oxygen

Baker, Abu; Mg, Ormerod

doi:10.1016/0005-2787(66)90264-4

Cited by 11 publications

(1 citation statement)

References 17 publications

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“…The mechanism by which cysteamine protects is unknown but it may be related to its protective action against the effect of oxygen on irradiated E. coli (Baker et al 1966).…”

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confidence: 99%

Death Mechanisms in Airborne Escherichia coli

Benbough

1967

Journal of General Microbiology

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SUMMARYDifferences in survival of Escherichia coli (strain B) sprayed from distilled water into air and into nitrogen as a function of relative humidity (RH) are reported. Two mechanisms which may contribute to death of airborne bacteria are described. In air one death mechanism occurring at low RH is attributed to the action of oxygen causing damage to flavin-linked enzymes as a result of free radical activity. Free radical suppressors are therefore expected to protect airborne E. coli B. Also, electron transport inhibitors like sodium azide, 2,4-dinitrophenol and potassium cyanide are shown to protect E. coli B against lethal effects of oxygen. An analogy is drawn with effects of oxygen on freeze-dried E. coli B. A second death mechanism of E. coli B in air occurs at higher RH's and is considered to result from the effect of aerosolization on RNA synthesis. The activation of RNAse as a possible protection to bacteria in the post-aerosolization medium is discussed. I N T R O D U C T I O NBecause the effect of aerosolization upon bacteria survival is related in a complex manner to relative humidity (RH) of the atmosphere, earlier reports (Dunklin & Puck, 1948;Davis & Bateman, 1960;Bateman, McCaffrey, O'Connor & Monk, 1961) have suggested that bacterial sensitivity increases at certain critical degrees of dehydration. Later reports (Hess, 1965;Cox, 1966) have shown that other factors, e.g. spray fluid, oxygen content of the carrier gas and the collecting fluid, influence the disruption of vital structures and the unbalancing of metabolism. Kinetic studies indicate that : (i) the loss of viability of bacteria is not a simple process; (ii) first-order reactions do not apply; (iii) typically, death rate is initially high and subsequently diminishes progressively.The possibility that overlapping lethal mechanisms exist, makes it extremely difficult to identify bacterial death by a given mechanism in a given set of conditions. One approach to the problem is the use of inert atmospheres to limit the effect of gaseous factors. Another is comparison between results of analogous studies, such as freeze-drying experiments, to derive support for evidence produced in aerosol tests. This paper reports results of such investigations. METHODS Growth of organismsCultures of Escherichia coli (strain B) were grown in 100 ml. of a chemically defined medium for 16 hr at 37", using a shake flask technique. The medium consists of 21-2

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“…The mechanism by which cysteamine protects is unknown but it may be related to its protective action against the effect of oxygen on irradiated E. coli (Baker et al 1966).…”

mentioning

confidence: 99%