BIOSYNTHESIS AND CYTOPLASMIC ACCUMULATION OF A CHLORINATED CATECHOL PIGMENT DURING 3-CHLOROBENZOATE AEROBIC CO-METABOLISM IN PSEUDOMONAS-FLUORESCENS

A strain of Pseudomonas fluorescens was capable of co-metabolizing 3-c hlorobenzoic acid with the production of a chlorinated catechol black pigment. A peroxidase and another enzymatic activity referred to as a polyphenol oxidase were found to be involved m the oxidation of 4-chlo rocatechol to 4-chloro-1,2-benzoquinone, i.e. in the production of hig hly reactive substrates for pigment formation. Therefore, P. fluoresce ns cells were seen to take an active part not only in 3-chlorobenzoate mineralization but also in overall pigment production. pH was found t o be a key parameter in the regulation of the activity of P. fluoresce ns oxidoreductive enzymes. Ultrastructural investigations showed that electron dense granules of pigment were distributed throughout the cyt oplasm of Pseudomonas fluorescens cells grown in presence of 3-chlorob enzoate, as confirmed also by Thiery cytochemical investigations. In t hese cells, an extensive contraction of the cytoplasm as well as a sig nificant damage to the cell wall after two days of incubation, suggest ed that pigment production caused a premature death of the cells accom panied by the leakage of the cell content. Pigment production seemed t o occur mostly in the cytoplasmic context where the electron dense mat erial accumulates until it is released in the medium after the cell ly sis.