Superfund Research Program
Bacterial Degradation of High Molecular Weight PAH
Project Leader: Michael D. Aitken
Grant Number: P42ES005948
Funding Period: 1995-2018
Project Summary (1995-2000)
The objectives of this project are to study the bacterial biodegradations of high molecular weight polycyclic aromatic hydrocarbons (PAH), defined as those containing four or more aromatic rings. These compounds represent the highest health risks associated with PAH-contaminated soils, yet also tend to be the most recalcitrant to biodegradation. Some bacteria can degrade these compounds but cannot use them as growth substrates. Therefore, studies of how degradation mechanisms are induced, or "turned on," in these organisms are being pursued. Also under investigation are whether these non-growth substrates are degraded only partially to organic products that might accumulate as a result of natural biodegradation or during bioremediation efforts, and whether a given PAH is transformed to different products by bacteria, which seem to use different pathways for PAH degradation. A final objective of the project is to study how mass transfer processes influence the bioavailability of PAH, which as a class are highly insoluble in water and therefore are often not available to bacteria able to degrade them in environmental systems.