Confirmation of Occurrence of Hydroxamate Siderophores in Soil by a Novel Escherichia coli Bioassay

P E Powell; P J Szaniszlo; C P Reid

doi:10.1128/aem.46.5.1080-1083.1983

Confirmation of Occurrence of Hydroxamate Siderophores in Soil by a Novel Escherichia coli Bioassay

Appl Environ Microbiol. 1983 Nov;46(5):1080-3. doi: 10.1128/aem.46.5.1080-1083.1983.

Authors

P E Powell¹, P J Szaniszlo, C P Reid

Affiliation

¹ Department of Microbiology, The University of Texas at Austin, Austin, Texas 78712, and Department of Forest and Wood Sciences, Colorado State University, Fort Collins, Colorado 80523.

Abstract

The occurrence of ferrichrome-type hydroxamate siderophores in soil was confirmed. In the presence of the iron-scavenging chelator ethylenediamine[di(o-hydroxyphenylacetic)acid], soil extract stimulated the growth of an Escherichia coli strain possessing the ferrichrome transport protein (TonA) but did not stimulate growth of a strain lacking this protein (TonA). The siderophore concentration in a 1:1 (soil-water) extract was estimated to be approximately 78 nM. Specificity of the assay was supported by the absence of significant differential strain responses to ferric citrate, ferric 2,3-dihydroxybenzoate, enterochelin, ferrioxamine B, coprogen, and triacetylfusigen.