Exceptionally high carbon fixation and nitrogen assimilation rates in microbial mats of an alkaline soda lake
Bibliographic record
Abstract
Alkaline soda lakes, characterized by high pH and high concentrations of sodium and dissolved carbonates, support diverse alkaliphilic microbial communities. Using stable isotope probing with 13C-bicarbonate, 15N-ammonium, 15N-nitrate, and 15N-urea, we measured assimilation rates for carbon and nitrogen by microbial mats of alkaline Goodenough Lake, Canada. Our results showed extremely high carbon fixation rates averaging 24 g C/m2/day, equalling or exceeding rates measured fifty years ago in African alkaline soda lakes. Urea consumption occurred both during the day and during the night, but assimilation mainly occurred during the day. Ammonium assimilation was stable between day and night. Apparently, cyanobacteria preferred urea as a nitrogen source, whereas heterotrophs preferred ammonium. Two different cyanobacteria dominated the microbial mats, Nodosilinea and Sodalinema. Using Orbitrap mass spectrometry, we only observed assimilation of 13C bicarbonate by Sodalinema, but not by Nodosilinea. The latter might focus on different carbon sources, such as urea. Strong negative correlation between their abundances in proteomes also supported niche partitioning between these two cyanobacteria.
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How this classification was reachedexpand
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) | 0.001 | 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 teacher head, 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".