Crude oil degradation performance of a deep sea Rhodococcus PC20 strain under the influence of elevated hydrostatic pressure and dispersant

A new bacterium, able to degrade mineral oil was isolated from the Deepwater Horizon (DWH) site, which was identified (99% 16S sequence identity) as Rhodococcus erythropolis species. Rhodococcus PC20 was able to grow on crude oil and single hydrocarbon components: even alkanes (nC6, nC10, nC16) and poly aromatic compounds like benzene and naphthalene. PC20 was able to degrade 60.5 ± 10.7 % of the saturated and aromatic fraction of crude oil at surface level (0.1 MPa) and 74.2 ± 9.1 % at deep sea level (1500 m bsl, 15 MPa) after 96h. Degradation rates especially for the BTEX compounds were significantly higher at elevated pressure compared to sea level pressures. Nevertheless, growth rates were not influenced by the applied pressure to a significant extend. Dispersant (EC9500A) to oil ratios (DOR) of 1:100 and higher demonstrated a metabolism and growth inhibiting effect on PC20.