Growth and Attachment-Facilitated Entry of Bacteria into Submicrometer Pores Can Enhance Bioremediation and Oil Recovery in Low-Permeability and Microporous Media
Bibliographic record
Abstract
Bioremediation end points for biodegradable hydrophobic compounds in soil aggregates are regulated by bacterial accessibility to different pore sizes. We evaluated the accessibility of the nonmotile hydrocarbon-degrading bacterium Dietzia maris ( d = 1 μm in the stationary phase) to 0.4 μm pores. A significant fraction (22%) of the pore volume of the clayey soil from which the bacterium was isolated was associated with 0.4–1 μm diameter pores. The entry of bacteria into the pores was observed by electron microscopy and by monitoring mineralization of [ 14 C]hexadecane placed well above membranes with fixed pore sizes (0.4 or 3 μm), in a bioreactor. The membranes were used as a surrogate for soil pores of fixed diameters. When membranes were not wetted or were wetted with nonbiodegradable heptamethylnonane, bacteria did not penetrate pores even if they attached to the membrane. However, bacteria penetrated pores when membranes were wetted with hexadecane, as growth on hexadecane yielded a crowd of smaller rod-shaped cells ( d min = 0.54 ± 0.14 μm) in biofilms formed on the membrane. A morphological progression with time from smaller, elongated cells in the early growth phase to cocci-shaped cells was observed. The results suggest proliferation accompanied by morphological changes as a mechanism of bacterial migration in submicrometer pores and low-permeability media.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".