Characterization of a degradative plasmid coding for metabolism of 3-chlorobenzoate by Pseudomonas putida and its expression in Escherichia coli

Pseudomonas putida DP4 was isolated from an enrichment culture with 3-chlorobenzoate (3-Cba) as sole source of carbon and energy. This strain was adapted to grow on 3-Cba at higher concentrations and maximum growth was observed at 12.8 mM of 3-Cba with 0.5 mM glucose as co-substrate. Further increase in the concentration of 3-Cba resulted in lower growth and degradation efficiency. The degradation of 3-Cba was not complete, since accumulation of the corresponding chlorocatechol resulted in inhibition of metabolism. The genes coding for the metabolism of 3-Cba were found to be plasmid-borne. The purified plasmid was transformed to rec(-) Escherichia coli DH5 at a rate of 2.28 X 10(4). The transformed cells were able to grow on 3.2 mM of 3-Cba and showed the presence of a corresponding plasmid DNA profile.