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Record W640395766

Microbial oxidation of arsenite at low temperatures

2011· dissertation· en· W640395766 on OpenAlexaboutno aff
T.H. Osborne

Bibliographic record

VenueUCL Discovery (University College London) · 2011
Typedissertation
Languageen
FieldEnvironmental Science
TopicArsenic contamination and mitigation
Canadian institutionsnot available
Fundersnot available
KeywordsArseniteArsenateArsenicBiofilmEnvironmental chemistryBiologyChemistryMicrobiologyBacteriaGeneticsOrganic chemistry
DOInot available

Abstract

fetched live from OpenAlex

Arsenic is toxic to most living cells and has two soluble inorganic forms: arsenite (+3) \nand arsenate (+5), which are ubiquitous in the environment. Microbial metabolism of \narsenic in the environment, contributes to its geochemical cycling. Prokaryotic \noxidation of arsenite has been reported and characterised in moderate and thermal \nenvironments but not below 10°C. \nGiant Mine is a discontinued gold mine located 250 miles south of the arctic circle in \nthe Northwest Territories, Canada. 230,000 tonnes of arsenic trioxide dust are stored \nunderground at the site and infiltrating surface waters have become contaminated with \n>50 mM arsenic. Several microbial biofilms were found growing on the mine walls \nbeneath seepage points of the arsenic-contaminated water. The diversity of arsenite \noxidisers in two sub-samples (which differed in arsenite concentrations) of one biofilm \nwere compared using a functional gene approach. The diversity of the two sub-samples \ndid not differ but the relative abundance of the three identified clades did. \nAn arsenite-oxidising bacterium, designated GM1, was isolated from the Giant Mine \nbiofilm. GM1 was shown to be a member of the Polaromonas genus, had a growth \nrange of 0-25°C and oxidised arsenite in the early-log phase of growth. GM1’s arsenite \noxidase was constitutively expressed. The arsenite oxidase genes were partially \nsequenced and their role in arsenite oxidation confirmed by mutagenesis. \nThe arsenite oxidase of GM1 was purified and partially characterised. It consists of two \nsubunits (88 and 15 kDa) in a α1β1 conformation, and contained Mo and Fe as cofactors. \nThe Vmax, Kcat and Km were the highest of any known arsenite oxidase. The GM1 \narsenite oxidase functioned over a broad temperature range and was more active than \nthat of the mesophile NT-26 at low temperatures. It was also found to be less stable than \nthat of NT-26, as observed by circular dichroism spectroscopy.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame machine prediction

Teacher imitation

Not 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.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: metacan-v3-hybrid-931329e0061cValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Bench or experimental · Consensus signal: Bench or experimental
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.002
Threshold uncertainty score0.004

Distilled classifier scores by category (both heads)

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0000.000
Scholarly communication0.0010.000
Open science0.0000.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0010.001

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.

Opus teacher head0.004
GPT teacher head0.172
Teacher spread0.168 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.

The models applied no category: nothing in the taxonomy fit this work.
Study designBench or experimental
Domainnot available
GenreEmpirical

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".

Quick stats

Citations0
Published2011
Admission routes1
Has abstractyes

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