1 research outputs found
Oil Biodegradation and Oil-Degrading Microbial Populations in Marsh Sediments Impacted by Oil from the Deepwater Horizon Well Blowout
To study hydrocarbon biodegradation
in marsh sediments impacted
by Macondo oil from the <i>Deepwater Horizon</i> well blowout,
we collected sediment cores 18–36 months after the accident
at the marshes in Bay Jimmy (Upper Barataria Bay), Louisiana, United
States. The highest concentrations of oil were found in the top 2
cm of sediment nearest the waterline at the shorelines known to have
been heavily oiled. Although petroleum hydrocarbons were detectable,
Macondo oil could not be identified below 8 cm in 19 of the 20 surveyed
sites. At the one site where oil was detected below 8 cm, concentrations
were low. Residual Macondo oil was already highly weathered at the
start of the study, and the concentrations of individual saturated
hydrocarbons and polycyclic aromatic hydrocarbons continued to decrease
over the course of the study due to biodegradation. Desulfococcus oleovorans, Marinobacter
hydrocarbonoclasticus, Mycobacterium
vanbaalenii, and related mycobacteria were the most
abundant oil-degrading microorganisms detected in the top 2 cm at
the oiled sites. Relative populations of these taxa declined as oil
concentrations declined. The diversity of the microbial community
was low at heavily oiled sites compared to that of the unoiled reference
sites. As oil concentrations decreased over time, microbial diversity
increased and approached the diversity levels of the reference sites.
These trends show that the oil continues to be biodegraded, and microbial
diversity continues to increase, indicating ongoing overall ecological
recovery