New metabolic insights into the microbial degradation of seawater-soluble crude oil components

Each year, millions of barrels of crude oil are released to the ocean from natural and anthropogenic sources. The fate of this crude oil, and more specifically, the degradation pathways mediated by microorganisms, are still under extensive investigation. In particular, the environmental fate and impacts of the polar oil components are poorly understood. We conducted a 14-day laboratory microcosm (2L) incubation experiment to examine the microbial degradation of polar molecules within the water-soluble fraction (WSF) of the Macondo surrogate oil. Our experiments contained natural marine microbial consortia under aerobic and nutrient replete conditions. Both internal and external metabolites were collected and analyzed using an untargeted metabolomics approach afforded by liquid chromatography coupled to electrospray ionization Fourier transform ion cyclotron mass spectrometry (FT-ICR-MS). Our results showed that (1) untargeted metabolomics data generated from state-of-the-art ultrahigh resolution mass spectrometry offers confirmation of previously hypothetical crude oil metabolic products, and, hence, can potentially identify new environmental markers for crude oil metabolism; (2) an unique set of metabolites are produced by microbes exposed to WSF; and (3) the diversity of compounds increases over the course of the incubation, suggesting that more attention should be paid to metabolic products of crude oil for a better understanding of the ecological and environmental impacts following marine oil spills.