The formation of phenol in the degradation ofp-hydroxybenzoic acid byKlebsiella aerogenes (Aerobacter aerogenes)

After growth ofK. aerogenes in chemically defined media consisting of mineral salts andp-hydroxybenzoate with or without glucose, phenol was found in the culture fluid at concentrations inhibiting further growth. Bacteria adapted to mineral salts medium containingp-hydroxybenzoate as sole source of carbon and energy produced small but isolable quantities of 3,4-dihydroxybenzoic acid and catechol and oxidized these substances as rapidly asp-hydroxybenzoate. Bacteria adapted to mineral salts medium containing glucose as sole carbon and energy source did not oxidizep-hydroxybenzoate, 3,4-dihydroxybenzoate or catechol. Bacteria adapted to glucose medium or top-hydroxybenzoate medium did not oxidize or utilize phenol as sole carbon and energy source. A metabolic pathway forp-hydroxybenzoate degradation is proposed and the formation of phenol is attributed to a side reaction.