Some Factors Influencing Bacterial Penetration of Eggs

Miller, William A.; Crawford, Lucy

doi:10.3382/ps.0320303

Cited by 22 publications

(2 citation statements)

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“…Even if only a single bacterial cell penetrated, it would multiply rapidly in the inner nutrient broth and give a positive result. Under more natural conditions, penetration of the shell membranes is undoubtedly a much slower process (14,4,6,10). Also, in the whole egg, the single bacterial cell or small group of cells which penetrate the membranes may die out in the unfavorable environment of the albumen.…”

Section: Alcaligciaes Bookrri ( a ) Profcits Nielanoz~ogenesmentioning

confidence: 99%

Protective Role of Shell Membranes in Bacterial Spoilage of Eggs

Garibaldi

Stokes

1958

Journal of Food Science

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The three main barriers which protect the shell egg against bacterial invasion and spoilage are the shell itself, the adjacent shell membranes, and the albumen (8). There is need for additional information on the degree of effectiveness of each of these barriers, on the mechanisms by which they either exclude bacteria or prevent their multiplication, and on the means by which invading bacteria surmount these obstacles.The present investigations deal with the shell membranes. These parchment-like envelopes which enclose the egg contents are composed of interlacing fibers of a keratin-like protein. The inner membrane is coated on the albumen side with a mucin-like substance which fills the interstices of the fiber network to form an apparently non-porous structure. Despite their thinness, the membranes constitute a tough, flexible envelope. This suggests that the membranes may function as a mechanical barrier to the penetration of bacteria into the egg. There is, however, no direct evidence that the membranes are impermeable to bacteria (4). The suggestion that the membranes have bactericidal properties (12) has been shown to be incorrect (9).Our investigations were undertaken to determine the ability of the egg shell membranes to filter out bacteria, to resist break-through by growing cultures of bacteria, and to support bacterial growth. The extent to which membranes are susceptible to proteolytic digestion by egg spoilage bacteria was also investigated. MATERIALS AND METHODSBacteria. The bacteria used were mainly those isolated by Florian and Trussell (3) and classified by them according to their ability to spoil eggs. They included 7 strains of Pseudomonas fluorescens; 2 strains of Pseudomonas piitrefaciens; 2 strains of Alcaligenes r e d ; 6 strains o f Alcaligenes bookeri ( a ) ; 2 strains of Alcaligenes bookeri ( b ) ; 3 strains ofAlcaligenes faecalis; 1 strain of Alcaligenes metalcaligenes; 3 strains of Aerobacter cloacae; 2 strains of Flavobacierium invisible; 4 unidentified species of Flavorbacterium; 4 strains of Achromobacter liquifaciens; 2 unidentified species of Achromobacter; 3 strains of Proteus melanovogenes; 5 strains of Proteus vulgaris ( a ) ; 2 strains of Proteus vulgaris ( b ) ; 2 strains of Paracolobactrum intermedium (b); 2 strains of Paracolobactrum aerogenoides; 3 strains of Escherichia freundii; 1 strain of Escherichia iniermediunt; and 2 unidentified species of the coli-aerogenes group.The cultures were maintained on trypticase soy agar slants. They were transferred to fresh slants monthly, incubated at 30" C. for 20 to 24 hours and stored at 3" C. until used. Liquid cultures were grown in trypticase soy broth at 30" C. for 20-24 hours and were used as inocula without .further treatment. All dilutions used in determining bacterial numbers were made in 0.25% tryptone. Such diluents have been shown to exert a protective action on bacteria (11) by preventing a reduction in numbers while the bacterial population is being determined. Filtration studies. The ability of the egg shell and membr...

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Section: Alcaligciaes Bookrri ( a ) Profcits Nielanoz~ogenesmentioning

confidence: 99%

Protective Role of Shell Membranes in Bacterial Spoilage of Eggs

Garibaldi

Stokes

1958

Journal of Food Science

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“…contents of 90% of newly laid eggs are free from micro-organisms. From fresh eggs Gram positive bacteria, apparently ovarian in origin (Harry, 1963a), have been recovered most frequently whereas organisms capable of growing in the contents of the egg are of rare occurrence (Hadley & Caldwell, 1916; Haines, 1938;Miller & Crawford, 1953). Thus it would appear that the common contaminants of rotten eggs are normally of extragenital origin.…”

Section: 'mentioning

confidence: 99%

The Properties and Classification of the Predominant Bacteria in Rotten Eggs

Board¹

1965

Journal of Applied Bacteriology

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A collection of 226 strains of badteria was assembled from eggs which had rotted on the premises of the producer and from others which had been allowed t o rot in the laboratory a t 10, 20 or 30". A majority of the eggs had a mixed infection. All but 8 of the isolates were Gram negative rods. The predominant types were Alcaligenes faecalis, Aeromonas liquefaciens, Proteus vulgarin, Cloaca spp., Citrobacter sp. and Pseudomonas JEuorescens. A nonpigmented pseudomonad could not be identified with any of the species included in Pseudomonas.

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