Abstract
The blowout of the Deepwater Horizon in the Gulf of Mexico in 2010 occurred at a depth of 1500 m, corresponding to a hydrostatic pressure of 15 MPa. Up to now, knowledge about the impact of high pressure on oil-degrading bacteria has been scarce. To investigate how the biodegradation of crude oil and its components is influenced by high pressures, like those in deep-sea environments, hydrocarbon degradation and growth of two model strains were studied in high-pressure reactors. The alkane-degrading strain Rhodococcus qingshengii TUHH-12 grew well on n-hexadecane at 15 MPa at a rate of 0.16 h−1, although slightly slower than at ambient pressure (0.36 h−1). In contrast, the growth of the aromatic hydrocarbon degrading strain Sphingobium yanoikuyae B1 was highly affected by elevated pressures. Pressures of up to 8.8 MPa had little effect on growth of this strain. However, above this pressure growth decreased and at 12 MPa or more no more growth was observed. Nevertheless, S. yanoikuyae continued to convert naphthalene at pressure >12 MPa, although at a lower rate than at 0.1 MPa. This suggests that certain metabolic functions of this bacterium were inhibited by pressure to a greater extent than the enzymes responsible for naphthalene degradation. These results show that high pressure has a strong influence on the biodegradation of crude oil components and that, contrary to previous assumptions, the role of pressure cannot be discounted when estimating the biodegradation and ultimate fate of deep-sea oil releases such as the Deepwater Horizon event.
Highlights
From April to July 2010, 779 million litres of oil were released into the Gulf of Mexico when the Deepwater Horizon (DWH) drilling rig platform exploded (Atlas and Hazen 2011)
S. yanoikuyae continued to convert naphthalene at pressure >12 MPa, at a lower rate than at 0.1 MPa. This suggests that certain metabolic functions of this bacterium were inhibited by pressure to a greater extent than the enzymes responsible for naphthalene degradation. These results show that high pressure has a strong influence on the biodegradation of crude oil components and that, contrary to previous assumptions, the role of pressure cannot be discounted when estimating the biodegradation and ultimate fate of deep-sea oil releases such as the Deepwater Horizon event
We investigated the biodegradation of two representatives of the main fractions of oil by two different bacterial model strains: Rhodococcus qingshengii TUHH-12, a degrader of the alkane n-hexadecane; and Sphingobium yanoikuyae B1, a bacterium capable of utilizing naphthalene, a polycyclic aromatic hydrocarbon (PAH) (Gibson et al 1973)
Summary
From April to July 2010, 779 million litres of oil were released into the Gulf of Mexico when the Deepwater Horizon (DWH) drilling rig platform exploded (Atlas and Hazen 2011). This event was the largest marine oil spill in history. The National Research Council (2003) estimated an overall input of about 1.3 Mt oil per year into the marine environment from all sources. 47% originates from natural seeps and the remaining 53% comes from activities related to the extraction, transportation and consumption of crude oil or refined products (National Research Council 2003). In case of the Deepwater Horizon accident, it is estimated that a substantial proportion of the hydrocarbons et al 2010; Kessler et al 2011; Redmond and Valentine 2012; Valentine et al 2012)
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