Evidence for the occurrence of specific iron (III)-binding compounds in near-shore marine ecosystems

Aqueous extracts of samples from representtive types of near-shore marine ecosystems were examined for growth-promoting activity for the siderochrome auxotroph, Arthrobacter JG-9. Blue-green algal mat and sea grass samples gave strongly positive responses. Relative to Desferal (Ciba Pharmaceutical Co., Summit, N.J.), concentrations up to 110 ng/g (wet weight) of sample were found. In contrast, extracts of anaerobic muds or macroalgae gave no detectable activity. The hydroxamate type of iron chelator may be important in providing a form of iron in sea water readily utilized by the microalgae and marine higher plants.