Effects of High-Molecular-Weight Polycyclic Aromatic Hydrocarbons on Microbial Ecology and Community Structure

Polycyclic aromatic hydrocarbons (PAHs) comprise as much as 7% of crude oil released naturally or anthropogenically to the environment, especially beaches and open ocean. These toxic, carcinogenic molecules are ubiquitous in nature and pose significant human health and environmental risks. Of particular interest are higher-molecular-weight PAHs such as benzo[a]pyrene and the dibenzopyrene family. These and other high-molecular-weight PAHs are highly toxic and mutagenic to mammalian and microbial cells alike, and can have significant long-term ecological effects due to their intense hydrophobicity and tendency to bioaccumulate. This dissertation seeks to improve the general understanding of these recalcitrant molecules, particularly as regards the ability of known alkane- and PAH-consuming bacteria to biodegrade them. Additionally, the impact of individual and collective isomers on microbially community structure and function is probed, by means of high-throughput sequencing (HTS) and bioinformatics. In essence, the ecological and community effects are similar among the individual isomers, while none of the high-molecular-weight PAHs responded favorably to attempts at biodegradation