Physical state of phenanthrene for utilization by bacteria

Area of Science:

• Microbiology
• Environmental Science
• Biochemistry

Background:

• Polycyclic aromatic hydrocarbons (PAHs) like phenanthrene are environmental pollutants.
• Microbial degradation is a key process for removing PAHs.
• Understanding the bioavailability of PAHs to microbes is crucial for effective bioremediation.

Purpose of the Study:

• To determine if bacteria utilize phenanthrene from solid particles or dissolved in the medium.
• To elucidate the mechanism of phenanthrene uptake by bacteria.

Main Methods:

• Growth experiments conducted in sealed, air-saturated fermentors.
• Phenanthrene used as the sole carbon source.
• Bacterial generation times measured via oxygen consumption rates.

Main Results:

• Bacterial generation times were consistent regardless of solid phenanthrene concentration.
• Generation times on solid phenanthrene medium matched those with only dissolved phenanthrene.
• Oxygen consumption rates indicated no difference in growth efficiency.

Conclusions:

• Bacteria access and utilize phenanthrene primarily in its dissolved state.
• Solid phenanthrene particles are not directly assimilated by these bacteria.
• This suggests that the dissolution rate of phenanthrene influences its bioavailability for microbial degradation.