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

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