Abstract
Grasses have been found to endure iron-deficiency by excreting form their roots mugineic acids which are able to dissolve ferric compounds by forming Fe(III)-complexes. However, mugineic acids were suspected to be rather quickly decomposed by soil microorganisms. The means that mugineic acid-decomposing microorganisms, if present, will mitigate the beneficial effect of the mugineic acids. In addition, the relation between excretion of mugineic acids and mugineic acid-decomposing microorganisms is considered to be a simple model of the relation between plant roots and their rhizospheric microorganisms in the water-cultured iron-deficient barley. Microflora both in the cultural solution and on the root surface appeared to be fairly simple and composed of bacteria. Six strains of mugineic acid-decomposing bacterium was isolated from the barley roots. On the contrary, no mugineic acid-decomposing bacterium was isolated from the cultural solution. This result suggests that the mugineic acid-decomposing bacteria are liable to be adsorbed on the surface of roots. One strain of the bacteria, which could quickly decompose mugineic acid, was judged to belong to Pseudomonas, though no known species were identical with this strain.
