Samples of egg melange taken from an egg packing station contained an average of 7·3 x 104 organisms/ml which survived laboratory pasteurization at 65°C for 3 min. Many of the organisms surviving pasteurization were found to be coryneform bacteria related to Microbacterium lacticum which could be differentiated into several groups. The remainder were a miscellaneous collection of unidentified cocci and coccobacilli and some Bacillus spp. The coryneform bacteria were shown to be the most heat‐resistant isolates with negligible loss of viability after 60 min at 65°C, At least two of the representative strains were very heat‐resistant, 0·01% surviving 20 and 38 min at 80°C in phosphate buffer at pH 7·1. Growth tests showed that none of the isolates grew at 5°C after 10 d incubation but those capable of growing most rapidly at 10° and 15°C were also the most heat‐resistant. Such strains had a doubling time at 15°C of between 6 and 8 h in whole egg. Freezing the coryneform bacteria in liquid whole egg at –18°C had negligible effect on viability or heat‐resistance at 65°C.

1. The ability of Streptococcus faecalis and Streptococcus faecium strains to survive in egg albumen and liquid whole egg before and after laboratory pasteurisation was studied. 2. Pasteurisation of egg albumen caused a decrease in viable cells of less than 10-fold, while pasteurisation of whole egg caused decreases of more than 100-fold in only two of the eight strains studied. After growth in whole egg, some strains were more resistant to pasteurisation in whole egg. 3. Strep. faecalis multiplied in raw and pasteurised whole egg but not in egg albumen. 4. Strep. faecium multiplied in raw and pasteurised whole egg only after an initial decline in viability which was not shown by cells adapted to whole egg. Together with storage temperature this affected the number of viable cells after a storage period of 5 d. 5. In raw and pasteurised egg albumen Strep. faecium strains lost viability; this was maximal at 37 degrees C and more cells survived as the storage temperature decreased.

Cells of Streptococcus faecalis that survived heating for 21 min at 60 degrees C were killed when resuspended at an initial cell density of about 1 X 10(8) viable units/mL and incubated at 33 degrees C for 24 h in a no-growth medium containing potassium phosphate buffer, pH 7.1, glucose, and casein hydrolysate. When such heated cells were resuspended at an initial cell density of about 1 X 10(7) viable units/mL or lower, subsequent cell death was reduced at least 10 000-fold. Unheated cells incubated under similar conditions at about 1 X 10(8) and 1 X 10(9) viable units/mL did not die. Cell death was due to a toxic compound synthesized by the heated cells, and supernatants from incubations showing a bactericidal effect contained a component, absent in nonlethal supernatants, that reacted with 2,4-dinitrophenylhydrazine. Thin-layer chromatography, mass spectrometer analysis, and the visible spectrum of the 2,4-dinitrophenylhydrazine derivative of the unknown and authentic methylglyoxal, and the positive response shown by the free unknown compound when used as a substrate for glyoxalase I, suggested that methylglyoxal was the bactericidal compound. Solutions of authentic methylglyoxal were bactericidal at concentrations above 0.2 mM and lethal supernatants contained about 1 mM methylglyoxal, whereas supernatants that were not lethal contained less than 0.02 mM methylglyoxal.