Arsenate-dependent growth is independent of an ArrA mechanism of arsenate respiration in the termite hindgut isolate <i>Citrobacter</i> sp. strain TSA-1
Bibliographic record
Abstract
Citrobacter sp. strain TSA-1 is an enteric bacterium isolated from the hindgut of the termite. Strain TSA-1 displays anaerobic growth with selenite, fumarate, tetrathionate, nitrate, or arsenate serving as electron acceptors, and it also grows aerobically. In regards to arsenate, genome sequencing revealed that strain TSA-1 lacks a homolog for respiratory arsenate reductase, arrAB, and we were unable to obtain amplicons of arrA. This raises the question as to how strain TSA-1 achieves As(V)-dependent growth. We show that growth of strain TSA-1 on glycerol, which it cannot ferment, is linked to the electron acceptor arsenate. A series of transcriptomic experiments were conducted to discern which genes were upregulated during growth on arsenate, as opposed to those on fumarate or oxygen. For As(V), upregulation was noted for 1 of the 2 annotated arsC genes, while there was no clear upregulation for tetrathionate reductase (ttr), suggesting that this enzyme is not an alternative to arrAB as occurs in certain hyperthermophilic archaea. A gene-deletion mutant strain of TSA-1 deficient in arsC could not achieve anaerobic respiratory growth on As(V). Our results suggest that Citrobacter sp. strain TSA-1 has an unusual and as yet undefined means of achieving arsenate respiration, perhaps involving its ArsC as a respiratory reductase as well as a detoxifying agent.
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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 | 0.001 | 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".