Absence of siderophore-like activity in Legionella pneumophila supernatants

Conflicting reports have been given as to the existence of a Legionella pneumophila siderophore. Hence, we rigorously examined the reported siderophore-like activity using the chrome azurol S indicator. Although chrome azurol S reactivity was detected in supernatants, control experiments indicate that it was due to cysteine in the media. When bacteria were cultured in media without cysteine, no siderophores were detected.