2,4-dichlorophenol Degradation by Indigenous Pseudomonas sp. PKZNSA and Klebsiella pneumoniae KpKZNSA: Kinetics, Enzyme Activity and Catabolic Gene Detection

In this study, two newly isolated 2,4-dichlorophenol(2,4-DCP)-degrading strains, Pseudomonas sp. KZNSA (PKZNSA) and Klebsiella pneumoniae KZNSA (KpKZNSA), were enriched from an activated sludge sample with a known history of contamination with chlorinated organic compounds collected from a wastewater treatment plant located in Durban, South Africa. The strains could use 2,4-DCP as sole carbon and energy source. PKZNSA and KpKZNSA degraded 64 and 49% of 2,4-DCP, with the degradation rate constant of 0.14 and 0.03 mg/L d, respectively. Both PKZNSA and KpKZNSA were found to harbor the catabolic genes that encode the enzymes involved in 2,4-DCP degradation via the ortho-pathway which is further confirmed by the specific enzyme activity assays. The strains did not possess genes that encode the enzyme maleylacetate reductase, which is involved in funneling the last intermediate (maleylacetate) in the pathway into the Krebs cycle. Findings from this study will be helpful in the exploitation of these microorganisms and/or their enzymes in developing bioremediation strategies for the chlorophenol-polluted environment.

Automated summary

Two newly isolated 2,4-dichlorophenol-degrading strains, Pseudomonas sp. KZNSA and Klebsiella pneumoniae KZNSA, were enriched from a wastewater treatment plant in Durban, South Africa. These strains could use 2,4-DCP as sole carbon and energy source, and harbored catabolic genes encoding enzymes involved in 2,4-DCP degradation via the ortho-pathway.