Electron-Spin Resonance Signals from Lyophilized Bacterial Cells Exposed to Oxygen

Lion, M. B.; Kirby-Smith, John S.; Randolph, M. L.

doi:10.1038/192034a0

Cited by 51 publications

(9 citation statements)

References 4 publications

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“…(1961) and Benedict et al (1961) reported that vacuum-lyophilized bacteria died rapidly after exposure to oxygen, even for such short intervals as a few minutes. The experiments of Lion, Kirby-Smith, and Randolph (1961) and those of Dimmick, Heckly, and Hollis (1961) show that the rapid killing due to this exposure is related to free-radical formation. In view of these findings, it is of particular interest that, in the present work, the survival of air-lyophilized bacteria as a function of residual moisture did not differ significantly from that of cells dried similarly in nitrogen.…”

Section: Survivalmentioning

confidence: 87%

Preservation of Bacteria by Circulating-Gas Freeze Drying

Wagman¹,

Weneck²

1963

Applied Microbiology

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Water-washed Serratia marcescens and Escherichia coli were freeze dried in a circulating-gas system at atmospheric pressure. This convective procedure resulted in a substantially higher survival of organisms than could be obtained by the vacuum method of freeze drying. There was little or no decrease in cell viability during convective drying when the residual moisture content was 15 %o or higher. Below this level, survival declined with decreasing moisture content. A detailed comparison of the convective and vacuum methods indicated that the advantage gained by freeze drying bacteria in air accrues in the early period of sublimation, at which time cells were found to be sensitive to vacuum drying but insensitive to air drying. An explanation for this difference is proposed, based upon the kinetics of water removal in the two processes. In brief, it is suggested that the convective method permits samples to be dried more uniformly; and regional over-drying, which may be deleterious even if transient, is thus avoided in achieving the optimal level of moisture.

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Section: Survivalmentioning

confidence: 87%

Preservation of Bacteria by Circulating-Gas Freeze Drying

Wagman¹,

Weneck²

1963

Applied Microbiology

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“…The protective action occurs therefore probably in the dry state and a certain amount of protective material is required for each organism to prevent the reaction between oxygen and some bacterial receptor. Nothing can as yet be said about the nature of this reaction, but free radicals are probably involved (Lion, Kirby-Smith & Randolph, 1961).…”

Section: Dpscijssionmentioning

confidence: 99%

Quantitative Aspects of the Protection of Freeze-Dried Escherichia coli Against the Toxic Effect of Oxygen

Lion

1963

Journal of General Microbiology

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SUMMARYVarious substances protect dry Escherichia coli against oxygen. The concentration of these substances in the bacterial suspension, necessary to achieve a given degree of protection, is a function of the concentration of the bacteria in the suspension. The protector seems to act in the dry state. The viability of freeze-dried bacteria, unexposed to oxygen, may also depend on the concentration of the bacterial suspension. A common mechanism is suggested to explain the dependence of killing on population density, both during freeze-drying and during exposure of dried organisms to oxygen. The viability of bacteria during freeze-drying and of dried bacteria exposed to oxygen are both markedly affected by the presence of certain substances such as serum albumin or Bacto-protone.

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“…Lyophilized bacteria are susceptible to oxygen upon exposure to air [1][2][3][4]. The dried bacteria, exposed to air lose their ability to form colonies on nutrient media, and "die" in an exponential fashion.…”

Section: Introductionmentioning

confidence: 99%