The Practical Significance in the Microbiological Examination of Cold Stored Foods of the Allegedly Low Heat Resistance among Psychrotrophic Organisms

Mossel, D. À. A.; Moosdijk, A. van de

doi:10.1111/j.1365-2672.1964.tb04906.x

Cited by 7 publications

(3 citation statements)

References 16 publications

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“…Microorganisms capable of growing at 5 C and below, according to Eddy (48), should be classified as psychrotrophic regardless of the optimum temperature and that the term psychrophile should be used only when a low optimum temperature is implied. There are many microbiologists who employ the term psychrotrophic (e.g., 47,102,114,137,186,189), and this term is gaining wider acceptance among food and dairy microbiologists. Ingram (86) gives the best reasons published in the literature as to why the term psychrotroph should be employed for most of the organisms listed in the literature as psychrophiles.…”

Section: Background Informationmentioning

confidence: 99%

Psychrophilic bacteria.

Morita¹

1975

Bacteriological Reviews

774

313

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Section: Background Informationmentioning

confidence: 99%

Psychrophilic bacteria.

Morita¹

1975

Bacteriological Reviews

774

313

View full text Add to dashboard Cite

“…1C), and plated at the appropriate dilution on TSA. To avoid the thermal damage associated with pour plating (14), the surface-plating technique was used. Colonies were counted after 48 h of incubation at 25°C.…”

Section: Methodsmentioning

confidence: 99%

Diluent sensitivity in thermally stressed cells of pseudomonas fluorescens

Gray¹,

Ordal²,

Witter³

1977

Appl Environ Microbiol

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Thermally injured cells of Pseudomonas fluorescens were unable to produce colonies on Trypticase soy agar (TSA) after dilution with 0.1% peptone. Nutritional exigency could not be used as the criterion for this injury, since varying the composition of the plating medium had little effect on the number of colonies that developed. The injured cells had no requirement for compounds known to leak out during the heat treatment in order to recover. The cells did not exhibit injury if dilution preceded heat treatment on the plating medium, demonstrating that the heat treatment sensitized the cells to the trauma of dilution. Substitution of 0.1% peptone with growth medium as the diluent largely offset the previously observed drop in TSA count. Little difference in survival was observed when monosodium glutamate or the balance of the defined medium was used as the diluent. The diluent effect was ionic rather than osmotic. The presence of cations was important in maintaining the integrity of the injured cell, and divalent cations enhanced this protective effect. The role of these cations at the level of the cell envelope is discussed.

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“…Provided the temperature of the agar is controlled when poured, this results in adequately standardized surface moisture conditions. Furthermore, this procedure also serves to test the plates for sterility (Mossel & van de Moosdijk 1964).…”

Section: P R O C E D U R Ementioning

confidence: 99%

Quality assurance of selective culture media for bacteria, moulds and yeasts: an attempt at standardization at the international level

Mossel

Laarhoven

Ligtenberg-Merkus

et al. 1983

Journal of Applied Bacteriology

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To facilitate monitoring of culture media, a simple quantitative streaking technique, implying ever-decreasing numbers of colony-forming units per surface area, as in spiral plating, was developed. The procedure evaluates, in quantitative terms, the ability of media (1) to support the formation of colonies by organisms that it was designed to grow and (2) to resist colonization by organisms that it is expected to suppress. The procedure was therefore termed ecometric evaluation. The ecometric results appeared to agree well with observations made on productivity and selectivity of the media studied during routine examination of specimens. These encouraging results prompted further, rigorous standardization of ecometry. A template was developed to standardize inoculation and the depth of the agar was controlled to within +/- 10%. Finally the attributes of the inocula used were accurately defined. The standardized ecometric technique has been found useful for the following purposes: (1) to assess the practical significance of the inhibitory effect of gentamicin observed in some moulds and yeasts (this was solved by replacing poorer basal media by one particular richer modification, viz, yeast morphology agar); (2) the development of a blood-free selective enumeration medium for Campylobacter jejuni, i.e. sulphide iron motility agar plus the combination of antibiotics suggested by Skirrow (1977); and (3) verification of the absence of antimicrobial activity of enzyme preparations, e.g. catalase, used in culture media to remedy sublethal damage in certain groups of bacteria. Ecometric evaluation can now be recommended for (1) routine monitoring of consignments of dehydrated or ready-to-use, purchased media; and (2) in-house checking of the functioning of medium preparation departments. Only occasionally is it necessary to use conventional counting techniques to confirm the results.

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The Practical Significance in the Microbiological Examination of Cold Stored Foods of the Allegedly Low Heat Resistance among Psychrotrophic Organisms

Cited by 7 publications

References 16 publications

Psychrophilic bacteria.

Psychrophilic bacteria.

Diluent sensitivity in thermally stressed cells of pseudomonas fluorescens

Quality assurance of selective culture media for bacteria, moulds and yeasts: an attempt at standardization at the international level

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