Bacterial Growth on and Penetration of the Shell Membranes of the Hen's Egg

Commonly occurring contaminants of rotten eggs multiplied in a buffered solution of mineral salts containing intact shell membranes. Aeromonas liquefaciens , a nonpigmented pseudomonad, and sometimes a proteolytic strain of a Cloaca sp. caused the membranes to lose their pink colour. This was associated with a marked increase in the turbidity of the suspending medium and with the appearance of substances which reacted with Nessler's reagent and ninhydrin. These changes were not seen after growth of Proteus vulgaris, Alcaligenes faecalis, Pseudomonas fluorescens or non-proteolytic strains of Cloaca spp. No differences were noted in the rate of penetration of the shell and shell membranes by these two groups.