UBC Theses and Dissertations
Some aspects of phenolic acid and iron metabolism in selected bacterial strains Walsh, Barry L.
Bacillus subtilis and Micrococcus lysodeikticus grew poorly when subjected to conditions of limiting iron nutrition after inocula were washed. Growth of both organisms was stimulated by ferrichrome and various phenolic acids. The chelating agents ethylene-diamine tetraacetic acid and nitrilotriacetic acid stimulated growth of B. subtilis but not of M. lysodeikticus . The effect of these compounds as antagonists to the action of the peptide antibiotic albomycin depended on growth conditions. Phenolic acid production by B. subtilis required relatively high levels of a carbon source, with glucose serving as the most effective substrate of those tested. B. subti lis WB746 produced only 2,3-dihydroxybenzoic acid whereas strain B1471 produced an unidentified phenolic acid early in log phase and 2,3-dihydroxy-benzoylglycine in the late log and early stationary phases of growth, under iron deficient conditions. Mutant strains of B. subtilis produced phenolic acids in the absence or presence of iron in the growth medium. DHB synthesizing enzymes were repressed by growth of B. subtilis in the presence of iron, ferrichrome or the aromatic amino acids. Active dihydroxybenzoic acid synthetase was not affected by these compounds. The DHB synthetase system from B. subtilis was partially purified by DEAE-cellulose column chromatography and sucrose gradient centrifugation; the result suggested the existence of a multienzyme complex. Iron uptake by B. subtilis and typhimurium was shown to be energy-dependent and repressible by growth in the presence of adequate iron. The iron uptake capacity of M. lysodei kticus appeared to be inducible, with a chelating agent or an Fe: chelate complex serving as the inducer. Ferrichrome and dihydroxybenzoic acid appeared to serve as iron transport factors for all three organisms, whereas ethylenediaminetetraacetic acid inhibited iron uptake. 3-F1uorobenzoic acid, a dihydroxybenzoic acid analog, had little effect on growth, but did reduce both phenolic acid production by, and iron uptake capacity of, Bacillus subtilis.