Some Nutritional Aspects of Bacterial Recovery From Ionizing Radiations

Stapleton, G. E.; Sbarra, Anthony J.; Hollaender, Alexander

doi:10.1128/jb.70.1.7-14.1955

Cited by 70 publications

(23 citation statements)

References 8 publications

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“…An attempt was made to prepare a synthetic medium which would substitute for the synthetic agar with added yeast extract. Stapleton et al (6) have shown that a modified Lactobacillus assay medium gave approximately the same activity as yeast or spleen extract, in promoting recovery of irradiated cells of Escherichk coli. A synthetic medium, very similar to that of Stapleton e t al.…”

Section: Resultsmentioning

confidence: 99%

EFFECT OF THE PLATING MEDIUM ON THE SURVIVAL OF HEAT‐TREATED CELLS OF PSEUDOMONAS FLUORESCENS^a

Heater

Zant

1957

Journal of Food Science

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Previous investigations ( 2 , 3, 6,) have shown that the characteristics of the growth medium used in studying survival of bacterial cells treated with heat or irradiation can have a pronounced effect on the number of survivors. Nelson ( 3 ) reported that certain heat-treated bacteria are more fastidious than others in their nutritional requirements. More recently, the same investigator ( 4 ) showed that the p H of the plating medium most favorable for growth of certain heat-treated organisms was not the same as for non-heated cells.Some practical aspects of these observations deserve attention. The number of viable bacteria in heat-processed foods can be determined only by an indirect method such as colony formation, which represents reproductive capacity. The possibility exists then that under one set of conditions in the plating medium some of the heat-treated bacteria appear nonviable because of lack of growth but, when different conditions are available, may prove to be viable.Although many investigations have shown that certain heat-treated bacteria grow better on the more complex rather than on simple media, few have shown a detailed study of the factors responsible for this phenomenon.The present study was initiated to determine some of the nutritional factors in the plating medium which can affect the number of survivors of heat-treated cells of Ps. fluorescens. EXPERIMENTAL METHODSCulture. Pseudomonas fluorescens 29 was used in all experiments. This organism was isolated from milk and identified in this laboratory. For the individual trials, Ps. fluorescens 29 was grown in a basal medium of the following composition: 1 g. of ILHPOI, 5 g. of NH,HBPOI, 5 g. of glucose, and 1 1. of distilled water. The medium was adjusted to pH 7.@ and autoclaved for 15 min. at 15 lb. steam pressure. Following inoculation, the culture was incubated at 25" C. for 24 hours. One per cent inoculum was used in all cases.Heating trials. One ml. of a 24-hour culture of Ps. fluorescens 29 in basal medium was added to 99 ml. of hot basal medium (pH 7.0), which had been adjusted to the desired temperature in a constant temperature water bath. The suspension was agitated continuously by a stirrer. At certain intervals samples were taken and cooled immediately in sterile screw-cap test tubes submerged in ice water.Plating media. Aliquots of the heat-treated and control (non-heated) suspensions were surface-plated on various solid media. The following media were employed: (a) nutrient agar (Bacto), (b) synthetic agar which contained the same ingredients as the basal medium with 15 g. of ggar per l., (c) synthetic agar supplemented with 0.1% yeast extract, Bacto-peptone, beef extract, or casamino acids, (d) synthetic agar supplemented with amino acids, purines and pyrimidines, and vitamins. The various man Journal Paper No. 2488 of the Texas Agricultural Experiment Station, College Station.

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Section: Resultsmentioning

confidence: 99%

EFFECT OF THE PLATING MEDIUM ON THE SURVIVAL OF HEAT‐TREATED CELLS OF PSEUDOMONAS FLUORESCENS^a

Heater

Zant

1957

Journal of Food Science

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“…Both strains are strongly influenced by postirradiation conditions of medium, incubation temperature and other factors, and particular influences seem to have the opposite effects on the two strains. Although both strains showed about the same survival on synthetic media , richer complex media gave rise to fewer survivors of E. coli B (Alper & Gillies, 1958) and higher counts of E. co2i B/r (Stapleton, Sbarra & Hollaender 1955). This 'medium effect' took place during the first few hours of incubation after irradiation, and it was concluded that the difference between the two strains lay not in the initial damage but in their metabolic processes immediately after irradiation .…”

Section: Systems For Studying Radiation Resistance (A) Escherichia Comentioning

confidence: 90%

Radiation Resistance among Bacteria

Thornley

1963

Journal of Applied Bacteriology

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Section: The Mediummentioning

confidence: 99%

“…Although consideration of the effect of the growth medium is outside the scope of this discussion, some reference must be made to this topic since the nutritional response after damage depends substantially on the nutrient capacity of the medium on which the culture is grown (Wright, 1917;Stapleton, Sbarra & Hollaender, 1955). Stapleton et al (1955) pointed out that with irradiated E . coli part of the total damage results from an impaired synthetic ability, and that this is less marked with cells grown in a minimal medium, and which have synthesized effective concentrations of the widest range of both enzymes and intermediates, than with those grown in a rich medium which permits growth in the presence of minimal concentrations of many of these substances.…”

Section: The Mediummentioning

confidence: 99%

The Influence of the Recovery Medium and the Incubation Temperature on the Survival of Damaged Bacteria

Harris¹

1963

Journal of Applied Bacteriology

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Some Nutritional Aspects of Bacterial Recovery From Ionizing Radiations

Cited by 70 publications

References 8 publications

EFFECT OF THE PLATING MEDIUM ON THE SURVIVAL OF HEAT‐TREATED CELLS OF PSEUDOMONAS FLUORESCENS^a

EFFECT OF THE PLATING MEDIUM ON THE SURVIVAL OF HEAT‐TREATED CELLS OF PSEUDOMONAS FLUORESCENS^a

Radiation Resistance among Bacteria

The Influence of the Recovery Medium and the Incubation Temperature on the Survival of Damaged Bacteria

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Some Nutritional Aspects of Bacterial Recovery From Ionizing Radiations

Cited by 70 publications

References 8 publications

EFFECT OF THE PLATING MEDIUM ON THE SURVIVAL OF HEAT‐TREATED CELLS OF PSEUDOMONAS FLUORESCENSa

EFFECT OF THE PLATING MEDIUM ON THE SURVIVAL OF HEAT‐TREATED CELLS OF PSEUDOMONAS FLUORESCENSa

Radiation Resistance among Bacteria

The Influence of the Recovery Medium and the Incubation Temperature on the Survival of Damaged Bacteria

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Product

Resources

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EFFECT OF THE PLATING MEDIUM ON THE SURVIVAL OF HEAT‐TREATED CELLS OF PSEUDOMONAS FLUORESCENS^a

EFFECT OF THE PLATING MEDIUM ON THE SURVIVAL OF HEAT‐TREATED CELLS OF PSEUDOMONAS FLUORESCENS^a