Abstract:

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.

Suggested Citation:

Hackbusch, Steffen; Bubenheim, Paul. 2018. Crude oil degradation performance of a deep sea Rhodococcus PC20 strain under the influence of elevated hydrostatic pressure and dispersant. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N77M06JF

Publications:

Hackbusch, S., Noirungsee, N., Viamonte, J., Sun, X., Bubenheim, P., Kostka, J. E., … Liese, A. (2020). Influence of pressure and dispersant on oil biodegradation by a newly isolated Rhodococcus strain from deep-sea sediments of the gulf of Mexico. Marine Pollution Bulletin, 150, 110683. doi:10.1016/j.marpolbul.2019.110683

Purpose:

Goal of this research was to obtain a Gulf of Mexico deep sea strain, able to grow on and degrade crude oil. The isolated strain Rhodococcus PC20 was subsequently tested for its performance, i.e. growth and activity, on degrading crude oil and its single components at different pressures (simulating different depths) and with the addition of dispersant.

Data Parameters and Units:

Date [MM/DD/YYYY]; T [time, in h]; ml [10^-3 liter]; Temperature [degrees Celsius]; rpm [rounds per minute]; CFU/ml [colony forming units per ml]; MPa [10^3 Pascal]; N [CFU / ml at time t, in CFU / ml]; N0 [CFU / ml at time t = 0 (starting concentration), in CFU / ml]; µ [growth rate, in 1/h]; t ½ [half times, in h]; k [first order kinetics constant, in 1/h].

Methods:

For the biodegradation (GC-MS) worksheet: Experiments named A - D correlate to different starting times (which further correlates to same inoculum cell concentrations). Experiment C was unable to be evaluated, therefore does not appear here. Experiment D was done in triplicates, therefore is named D1-3 (none at 24h and only D1 at 48h), where not all of them were able to be measured in the GC-MS at any timepoint. For calculation of half-lives, D1-3 were averaged and treated as a single experiment.

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