The influence of Pseudomonas putida CP1 on the Degradation of Mono-Chlorophenols by a Mixed Microbial Population

Abstract

A mixture of microorganisms, produced for the treatment of substituted aromatic compounds, was examined for its ability to degrade 2-, 3- and 4-chlorophenol, as sole carbon source, in aerobic batch culture. Complete degradation of mono- chlorophenols normally proceeds through a modified ortho-pathway. Metabolism of the mono-chlorophenols by the mixed culture, was shown to be via the meta-cleavage pathway. This resulted in incomplete metabolism of 2-chlorophenol (2-cp) and 3-chlorophenol (3-cp). 4-chlorophenol (4-cp), however, was shown to be successfully degraded (concentration 1.56 mmol I⁻¹), with metabolism resulting in a stoichiometric release of chloride.

P. putida CP1 is one of the few isolates reported to successfully degrade and dechlorinate all three mono-chlorophenols. Aerobic batch culture studies showed that P. putida CP1 was capable of completely degrading 1.56 mmol 1⁻¹ 2-cp, 0.78 mmol 1⁻¹ 3-cp and 2.34 mmol 1⁻¹ 4-cp with a stoichiometric release of chloride. This organism degraded the mono-chlorophenols via a modified ortho-cleavage pathway specific to chlorinated aromatics.

When P. putida CP1 was added to the mixed culture, the supplemented mixed culture could not only degrade 2-chlorophenol and 4-chlorophenol up to a concentration of 2.34 mmol 1⁻¹ and 3-chlorophenol up to a concentration of 1.56 mmol 1⁻¹, but it could degrade the mono-chlorophenols at a faster rate than when P. putida CP1 was used alone.