Production of a ferro-phenolic complex by Nocardia opaca and metabolism of phenolic acids in bacterial cultures

Abstract

During the growth of Nocardia opaca on the culture medium containing p-hydroxybenzoic acid as a carbon source, protocatechuic acid is generated and quickly becomes a part of the complex with iron and p-hydroxybenzoic acid. In the process of a logarithmic phase of the cell's growth, an active hydroxylase of p-hydroxybenzoic acid is constantly present in the culture. At the end of this growth phase, the activity of protocatechuate dioxygenase appears as well and the complex undergoes extensive decomposition with its components disappearing gradually from the medium. p-Hydroxybenzoic acid, even at high concentration, does not inhibit the growth of bacteria, whereas protocatechuic acid limits it significantly. On the other hand, p-hydroxybenzoic acid, which inhibits the activity of protocatechuate dioxygenase, causes excessive accumulation of protocatechuic acid in the culture. Generation of the ferro-phenolic complex which binds these two acids, probably protects the cells from the undesirable influence of their surplus.