Methanogenesis, sulfate reduction and crude oil biodegradation in hot Alaskan oilfields
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Petrochemical and geological evidence suggest that petroleum in most reservoirs is anaerobically biodegraded to some extent. However, the conditions for this metabolism and the cultivation of the requisite microorganisms are rarely established. Here, we report on microbial hydrocarbon metabolism in two distinct oilfields on the North Slope of Alaska (designated Fields A and B). Signature anaerobic hydrocarbon metabolites were detected in produced water from the two oilfields offering evidence of in situ biodegradation activity. Rate measurements revealed that sulfate reduction was an important electron accepting process in Field A (6-807 µmol S l(-1) day(-1)), but of lesser consequence in Field B (0.1-10 µmol S l(-1) day(-1)). Correspondingly, enrichments established at 55°C with a variety of hydrocarbon mixtures showed relatively high sulfate consumption but low methane production in Field A incubations, whereas the opposite was true of the Field B enrichments. Repeated transfer of a Field B enrichment showed ongoing methane production in the presence of crude oil that correlated with ≥ 50% depletion of several component hydrocarbons. Molecular-based microbial community analysis of the methanogenic oil-utilizing consortium revealed five bacterial taxa affiliating with the orders Thermotogales, Synergistales, Deferribacterales (two taxa) and Thermoanaerobacterales that have known fermentative or syntrophic capability and one methanogen that is most closely affiliated with uncultured clones in the H(2)-using family Methanobacteriaceae. The findings demonstrate that oilfield-associated microbial assemblages can metabolize crude oil under the thermophilic and anaerobic conditions prevalent in many petroleum reservoirs.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it