The influence of incubation temperature and pH on the antimicrobial properties of hen egg albumen

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Abstract
Gram-positive bacteria, including lysozyme-resistant strains, and yeasts were killed in hen egg albumen with or without Fe at 30.degree. or 39.5.degree. C. The albumen was more toxic at 39.5.degree. C than at 30.degree. C for gram-negative bacteria. With the exceptions of Pseudomonas fluorescens, Acinetobacter sp. and Proteus vulgaris, Fe caused the growth of gram-negative bacteria or protected them from being killed in hen albumen at 39.5.degree. C. At this temperature, maximal growth of and glucose utilization by Escherichia coli C20 only occurred in albumen supplemented with growth factors, trace metals, additional N and sufficient Fe to quench ovotransferrin. The bactericidal properties of albumen could be negated by changing its pH from .gtoreq. 9.0 to .ltoreq. 7.5. At 39.5.degree. C, enterochelin allowed growth of E. coli in albumen at pH 7.9, but not at 9.4; Fe allowed growth at both pH values.