Related Experiment Video
Updated: May 4, 2026
Author Spotlight: Quantifying Siderophores and Pyochelin for Infection Control
Published on: March 15, 2024
Phenanthrene mineralization by Pseudomonas sp. UG14
M A Providenti1, C W Greer, H Lee
1, .
Abstract:
A phenanthrene-mineralizing Pseudomonas sp., designated UG14, was isolated from creosote-contaminated soil. It contained two plasmids, of approximately 77 kb and 76 kb, the smaller of which contained DNA sequences that hybridized with probes specific for ndoB and xylE, genes involved in catabolism of aromatic hydrocarbons. At initial phenanthrene concentrations of 10, 50, 200 and 1000 mg/l broth, 27%, 19%, 7.7% and 3.3%, respectively, of the [9-(14)C]phenanthrene was recovered as (14)CO2 after 36 days' incubation at 30°C. Most (14)C-label was converted to a water-soluble metabolite tentatively identified as 1-hydroxy-2-naphthoic acid. Rhamnolipid biosurfactants produced by P. aeruginosa UG2 enhanced mineralization of 50 mg phenanthrene/l by Pseudomonas sp. UG14. With the biosurfactant at 0, 25 and 250 mg rhamnose equivalents/l, 6.5%, 8.2% and 9.8%, respectively, of the phenanthrene was mineralized after 35 days.
Insights
A novel Pseudomonas sp. (UG14) effectively mineralizes phenanthrene, a key component of creosote. Biosurfactants significantly enhance this process, offering a promising bioremediation strategy for contaminated sites.
Area of Science:
- Environmental Microbiology
- Bioremediation
- Polycyclic Aromatic Hydrocarbon (PAH) Degradation
Background:
- Creosote contamination poses significant environmental challenges due to persistent polycyclic aromatic hydrocarbons (PAHs) like phenanthrene.
- Microbial degradation is a key strategy for remediating PAH-contaminated soils and water.
Purpose of the Study:
- To isolate and characterize a microorganism capable of mineralizing phenanthrene.
- To investigate the role of specific genes and plasmids in phenanthrene degradation.
- To evaluate the effect of biosurfactants on enhancing phenanthrene mineralization.
Main Methods:
- Isolation of phenanthrene-degrading bacteria from contaminated soil.
- Plasmid profiling and Southern hybridization to identify relevant genes (ndoB, xylE).
- Radiotracer experiments ([9-(14)C]phenanthrene) to quantify mineralization rates at various concentrations.
- Identification of metabolites using analytical techniques.
- Assessment of biosurfactant (rhamnolipid) enhancement of phenanthrene mineralization.
Main Results:
- A Pseudomonas sp. (UG14) capable of phenanthrene mineralization was isolated.
- UG14 possesses plasmids, with the smaller one containing genes homologous to ndoB and xylE, crucial for aromatic hydrocarbon catabolism.
- Mineralization efficiency decreased with increasing initial phenanthrene concentration (27% at 10 mg/l to 3.3% at 1000 mg/l).
- 1-hydroxy-2-naphthoic acid was identified as a major water-soluble metabolite.
- Rhamnolipid biosurfactants significantly enhanced phenanthrene mineralization by Pseudomonas sp. UG14, increasing it from 6.5% to 9.8% with increasing biosurfactant concentration.
Conclusions:
- Pseudomonas sp. UG14 is a promising candidate for phenanthrene bioremediation.
- The presence of specific catabolic genes on plasmids contributes to its degradation capabilities.
- Biosurfactant application can improve the efficiency of microbial phenanthrene degradation, highlighting a potential strategy for enhanced bioremediation of creosote-contaminated environments.
