Survival of Serratia Marcescens After Freeze-Drying or Aerosolization at Unfavorable Humidity I.

Zimmerman, Leonard N.

doi:10.1128/jb.84.6.1297-1302.1962

Cited by 23 publications

(11 citation statements)

References 5 publications

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“…Aerosols were generated with a pneumatic disseminator designed by E. G. Flurie (C. S. Cox et al, unpublished data; E. G. Flurie and C. Rodderick unpublished data), and were stored in a rotating drum (5). Freeze-dried powders were prepared from distilled water-washed 16-hr cultures of Escherichia coli B by using a "waffle iron" freeze-drier (15). After preparation, the powders were stored in vacuo at -70 C. RH was controlled by mixing wet and dry streams of gas.…”

Section: Methodsmentioning

confidence: 99%

Aerosol Survival of Escherichia coli B Disseminated from the Dry State

Cox¹

1970

Applied Microbiology

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Survival was determined for Escherichia coli B disseminated as an aerosol from the dry state. Survival in nitrogen, like that for wet dissemination, was better at low than at high relative humidity (RH). At high RH, survival was characterized by critical zones of instability in survival as a function of RH, instability occurring at 100, 95, 78, 70, and 60% RH. In air, survival was inferior to that in nitrogen at low RH, whereas the converse was found at high RH. The effect was attributed to oxygen. In general, results support the conclusion that to the first approximation survival is related to bacterial water content, the latter increasing with RH. However, a more detailed analysis of results indicates that survival might not be exactly related to bacterial water content. It is shown that death occurred because of rehydration and that the pretreatment of E. coli B affected its aerosol stability characteristics; i.e., wet and dry disseminated aerosols are not equivalent.

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Section: Methodsmentioning

confidence: 99%

Aerosol Survival of Escherichia coli B Disseminated from the Dry State

Cox¹

1970

Applied Microbiology

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“…Center, Oakland, Calif. 94625 drier (9). One characteristic of the freeze-drier was that 15-ml serum bottles were used to contain the freeze-dried material.…”

Section: Methodsmentioning

confidence: 99%

Experimental Technique for Studying Aerosols of Lyophilized Bacteria

Cox¹,

Derr²,

Flurie³

et al. 1970

Applied Microbiology

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An experimental technique is presented for studying aerosols generated from lyophilized bacteria by using Escherichia coli B, Bacillus subtilis var. niger, Enterobacter aerogenes, and Pasteurella tularensis. An aerosol generator capable of creating fine particle aerosols of small quantities (10 mg) of lyophilized powder under controlled conditions of exposure to the atmosphere is described. The physical properties of the aerosols are investigated as to the distribution of number of aerosol particles with particle size as well as to the distribution of number of bacteria with particle size. Biologically unstable vegetative cells were quantitated physically by using 14C and Europium chelate stain as tracers, whereas the stable heat-shocked B. subtilis spores were assayed biologically. The physical persistence of the lyophilized B. subtilis aerosol is investigated as a function of size of spore-containing particles. The experimental result that physical persistence of the aerosol in a closed aerosol chamber increases as particle size is decreased is satisfactorily explained on the bases of electrostatic, gravitational, inertial, and diffusion forces operating to remove particles from the particular aerosol system. The net effect of these various forces is to provide, after a short time interval in the system (about 2 min), an aerosol of fine particles with enhanced physical stability. The dependence of physical stability of the aerosol on the species of organism and the nature of the suspending medium for lyophilization is indicated. Also, limitations and general applicability of both the technique and results are discussed.

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“…As described elsewhere, the cells used in these studies were grown in a glucose-tryptose medium and then were centrifuged, resuspended in the supernatant liquid, and frozen (18). Quantities of frozen suspension were thawed, and weighed amounts were dispensed into centrifuge tubes to permit the preparation of pellets of packed cells.…”

Section: Methodsmentioning

confidence: 99%

Permeability of Serratia marcescens to Some Inorganic Salts

Zimmerman¹

1969

J Bacteriol

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The physical interactions between Serratia marcescens and solutions of NaCl, CaCl2, Cah2, Nal, and Na2HPO4 plus NaH2PO4 were examined. Dilute (0.017 N) salt solutions did not cause cells to lose water, as evidenced by the unchanged weight of centrifugally packed cells. The cells preferentially adsorbed the cations and repelled the anions of most salts in these solutions. Concentrated (1.71 N) salt solutions markedly reduced the weight and water content of centrifugally packed cells, although these cells took up considerable amounts of salts. More than 90% of the water in the packed-cell pellets was available for the solution of NaCl at 4.2 to 4.4% concentration. The observation that salts apparently penetrated the cells freely and yet caused extensive dehydration was not readily compatible with conventional concepts of solute-induced plasmolysis. Alternative hypotheses to explain the data included the following. First, the cells lost weight and water to concentrated salt solutions through a nonosmotic competitive dehydration, causing a shrinkage of the protoplasmic gel. The shrinkage ofthe cell wall was limited because of the rigidity of its mucopeptide layer; therefore, a space appeared between the cell wall and the cell membrane. Second, cells may have equilibrated their water activity with that of their environment by two mechanisms: (i) the loss of water by plasmolysis or competitive dehydration, and (ii) alterations in cell permeability that admitted previously excluded solutes to the cell interior. Possibly, the correct explanation of the observations reported here involves elements of all three hypotheses, plasmolysis, competitive dehydration, and permeability alterations.

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Survival of Serratia Marcescens After Freeze-Drying or Aerosolization at Unfavorable Humidity I.

Cited by 23 publications

References 5 publications

Aerosol Survival of Escherichia coli B Disseminated from the Dry State

Aerosol Survival of Escherichia coli B Disseminated from the Dry State

Experimental Technique for Studying Aerosols of Lyophilized Bacteria

Permeability of Serratia marcescens to Some Inorganic Salts

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