Abstract:

A mesocosom scale experiment was conducted to monitor the temporal changes in microbial hydrocarbon oxidation rates in response to the presence of oil and chemically dispersed oil. Water samples were incubated with 14°C labeled hexadecane and naphthalene and the amount of liberated 14°C labeled carbon dioxide will be measured as a proxy for hydrocarbon oxidation.

Suggested Citation:

Achberger, Amanda, Shawn Doyle, and Jason Sylvan. 2020. Rates of 14C hydrocarbon oxidation by microbial communities, LTMOSE, a Long Term Marine Oil Snow Experiment, oxidation rate measurements, a mesocosm experiment. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/3ZVPZ2F8

Publications:

Achberger, A. M., Doyle, S. M., Mills, M. I., Holmes, C. P., Quigg, A., & Sylvan, J. B. (2021). Bacteria-Oil Microaggregates Are an Important Mechanism for Hydrocarbon Degradation in the Marine Water Column. MSystems, 6(5). https://doi.org/10.1128/msystems.01105-21

Purpose:

Monitor the temporal changes in microbial hydrocarbon oxidation rates in response to the presence of oil and chemically dispersed oil.

Data Parameters and Units:

Substrate; treatment; timepoint; and oxidation rate (percent per hour).

Methods:

Rates of biological hydrocarbon oxidation were estimated using [1-14C] Hexadecane and [1-14C] Naphthalene (American Radiolabeled Chemicals Inc.). During each time point tested, 1 mL of water from each of the triplicate mesocosom tanks was collected in two 2mL microcentrifuge tubes. To each tube, 100,000 dpm (drops per minute) of either 14C-labeled hexadecane or naphthalene was added. The 2 mL microcentrifuge tubes were then placed upright into a 20 mL borosilicate glass scintillation vial, a carbon dioxide trap consisting of 100mls of 0.5N KOH and a fragment of GF/F filter paper in a 200ul tube were placed next to the microcentrifuge tube, and the scintillation vials were sealed with a silicone septum screw cap. The samples were incubated for 12-24 hours before being terminated with the addition of 50ul of 100% TCA injected through the septum cap. The samples were allowed to sit for another 6 hours before the traps were removed to allow for maximum absorbance of liberated 14CO2. The contents of the traps were transferred to a clean 20 mL scintillation vial and 10 mLs of CytoScint ES (MP Biomedicals) scintillation cocktail was added. Counts were measured for 3 minutes on a Beckman Coulter liquid scintillation counter. Killed controls were periodically tested throughout the experiment by either pasteurizing the sample at 80˚C for 1 hour or acidifying the sample to a pH ≤2 prior to the addition of radiolabeled substrate and incubation. Background incorporation detected in controls was subtracted from rates measured in samples. Samples were collected every 24 hours for the first 4 days, then every 48 hours until the end of the experiment.

Instruments:

Beckman Coulter liquid scintillation counter

Individual Files: