Catabolism of flocculosin, an antimicrobial metabolite produced by Pseudozyma flocculosa
Bibliographic record
Abstract
Flocculosin is an unusual cellobiose lipid secreted by the yeast-like fungus Pseudozyma flocculosa as part of its biocontrol arsenal against other fungi. Recent observations have suggested that the fungus degrades flocculosin to use it as a nutrient source during periods of food limitation. In this work, we sought to identify the catabolic steps leading to the degradation of flocculosin and its subsequent use by P. flocculosa. To this end, we characterized the catabolism of flocculosin through identification of degradation intermediates in a deprived medium using mass spectrometry. As the pH of the medium increased, the molecule was quickly deacylated and lost its antimicrobial activity thereby explaining conflicting results concerning the antimicrobial activity of this class of glycolipid. Following removal of both acetyl groups and the short fatty acid chain under alkaline conditions, the molecule was quickly and completely metabolized by P. flocculosa. Protein purification of culture filtrates confirmed the presence of degradative enzymes produced by P. flocculosa. These enzymes were found to degrade 3,15-dihydroxy-hexadecyl cellobioside (DHC) but not the acylated molecule, thus confirming the protective role of these groups against catabolism. These results are the first evidence of glycolipid degradation by producing organism and suggest that flocculosin can be recycled by P. flocculosa as a nutrient in addition to protecting its ecological niche.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| 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".