Catechin, a condensed tannin was utilized as sole carbon source byBradyrhizobium japonicum. Protocatechuic acid, phloroglucinolcarboxylic acid, phloroglucinol, resorcinol and hydroxyquinol were identified as intermediates of catechin degradation. The aromatic substrates favoured good growth up to 5 or 10 mm.B. japonicumtolerated up to 50 mmcatechin and phloroglucinolcarboxylic acid, 40 mmphloroglucinol and resorcinol, 30mmprotocatechuic acid and 10 mmhydroxyquinol. Catechin-induced cells oxidized catechin more rapidly than uninduced cells. The two final ring compounds of the catechin catabolic pathway, protocatechuic acid and hydroxyquinol, were oxidized differentially. The enzymes of the catechin degradative pathway were inducible inB. japonicum.
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