Biodegradation of phthalate esters by two bacteria strains

Area of Science:

• Environmental microbiology
• Bioremediation
• Organic pollutant degradation

Background:

• Phthalate esters (PAEs) are common environmental pollutants.
• Developing effective bioremediation strategies for PAEs is crucial.

Purpose of the Study:

• To isolate and identify aerobic bacteria capable of degrading PAEs.
• To evaluate the degradation efficiency of individual strains and their combination.
• To investigate the influence of co-contaminants on PAE biodegradation.

Main Methods:

• Isolation of PAE-degrading bacteria from river sediment and petrochemical sludge.
• Identification of bacterial isolates using standard microbiological techniques.
• Assessing the degradation rates of various PAEs by individual strains and their consortium.
• Investigating the impact of nonylphenol and polycyclic aromatic hydrocarbons (PAHs) on PAE degradation.

Main Results:

• Two aerobic strains, Sphingomonas sp. DK4 and Corynebacterium sp. O18, were isolated.
• DK4 and O18 efficiently degraded PAEs with shorter alkyl chains (e.g., DEP, DBP).
• Degradation rates were higher for strain DK4 than O18 and were enhanced when both strains were present simultaneously.
• Simultaneous presence of multiple PAEs also enhanced degradation rates.
• Nonylphenol and selected PAHs inhibited PAE degradation at 1 microg/g concentration.

Conclusions:

• Sphingomonas sp. DK4 and Corynebacterium sp. O18 are effective PAE degraders.
• A bacterial consortium of DK4 and O18 shows enhanced PAE biodegradation potential.
• PAE degradation is sensitive to the presence of other environmental contaminants like nonylphenol and PAHs.