Microbial community diversity in the phycosphere of natural populations of the toxic alga, <i>Alexandrium fundyense</i>
Bibliographic record
Abstract
The dinoflagellate Alexandrium fundyense is the major causative organism of paralytic shellfish poisoning in the Gulf of Maine. While laboratory studies have shown that A. fundyense population dynamics can be affected dramatically by co-occurring bacteria, little is known about these interactions in nature. Because A. fundyense is typically a minor Gulf of Maine phytoplankton community member, analyses of the bulk community cannot be used to address bacterium-A. fundyense associations. Therefore, an immunomagnetic bead method was used to selectively capture A. fundyense cells, and the bacteria attached to them, from complex natural samples. Bulk particle-associated and free-living bacterial communities were collected simultaneously. DNA was extracted from all sample types and subjected to 16S rRNA gene fragment amplification, denaturing gradient gel electrophoresis (DGGE) and sequence analysis. Ordination analysis of DGGE profiles confirmed that A. fundyense-associated bacteria community profiles were distinct from bulk bacterial community profiles, indicating selection of specific phylotypes in the A. fundyense phycosphere. Phylogenetic analyses confirmed that Alexandrium-associates were distinct from bulk particle-associated bacteria and that they included a greater prevalence and broader diversity of Gammaproteobacteria than previously thought to be associated with toxic algae. Phylogenetic groups known to be associated with dinoflagellates were also found, including members of the families Alteromonadaceae, Pseudoalteromonadaceae, Rhodobacteraceae and Flavobacteraceae.
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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 | 0.001 | 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".