Shewanella halifaxensis sp. nov., a novel obligately respiratory and denitrifying psychrophile
Bibliographic record
Abstract
Indigenous bacteria found in the sediment of the Emerald Basin (depth of 215 m, Atlantic Ocean) located offshore of Halifax Harbour (Nova Scotia, Canada) were previously found to be able to degrade the explosive compound hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). In the present study, a novel obligately respiratory, denitrifying and RDX-mineralizing bacterium, designated strain HAW-EB4(T), was isolated from the marine sediment. This bacterium utilized peptone, yeast extract, Casamino acids, esters (Tweens 20, 40 and 80), sugars (N-acetyl-D-glucosamine, ribose), several C2 and C3 acids (acetate, pyruvate, lactate, propionate) and amino acids (serine, proline) as sole carbon and energy sources. Aerobically grown cells (in marine broth 2216 at 10 degrees C) contained C(14 : 0) (6 %), iso-C(15 : 0) (12 %), C(16 : 0) (20 %), C(16 : 1)omega7 (37 %), C(18 : 1)omega7 (7 %) and C(20 : 5)omega3 (7 %) as major membrane fatty acids, and Q7 (28.1 %) and MK-7 (60.9 %) as dominant respiratory quinones, consistent with deep-sea species of Shewanella. The novel bacterium had a DNA G+C content of 45 mol% and showed similarity to Shewanella species in terms of 16S rRNA and gyrB gene sequences (93-99 and 67.3-88.4 % similarity, respectively), with Shewanella pealeana being the most closely related species. Genomic DNA-DNA hybridization between strain HAW-EB4T and S. pealeana revealed a level of relatedness of 17.9 %, lower than the 70 % species cut-off value, indicating that strain HAW-EB4T (= NCIMB 14093T = DSM 17350T) is the type strain of a novel species of Shewanella, for which the name Shewanella halifaxensis sp. nov. is proposed.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.001 |
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".