Characterization of <i>Klebsiella</i> sp. strain S1: a bacterial producer of secoisolariciresinol through biotransformation
Bibliographic record
Abstract
Secoisolariciresinol (SECO) is a lignan of potential therapeutic value for diseases such as cancer, but its use has been limited by the lack of ideal production methods, even though its precursors are abundant in plants, such as flaxseeds. Here, we report the characterization of a bacterial strain, S1, isolated from the human intestinal flora, which could produce secoisolariciresinol by biotransformation of precursors in defatted flaxseeds. This bacterium was a Gram-negative and facultatively anaerobic straight rod without capsules. Biochemical assays showed that it was negative for production of oxidase, lysine decarboxylase, ornithine decarboxylase, arginine dihydrolase, and β-glucolase. The G + C content of genomic DNA was 57.37 mol%. Phylogenetic analysis by 16S rRNA and rpoB gene sequences demonstrated S1's close relatedness to Klebsiella. No homologues were found for wzb or wzc (capsular genes), which may explain why Klebsiella sp. strain S1 does not have the capsule and was isolated from a healthy human individual. Based on the percentages of homologous genes with identical nucleotide sequences between the bacteria in comparison, we found that clear-cut genetic boundaries had been formed between S1 and any other Klebsiella strains compared, dividing them into distinct phylogenetic lineages. This work demonstrates that the intestinal Klebsiella, well known as important opportunistic pathogens prevalent in potentially fatal nosocomial infections, may contain lineages that are particularly beneficial to the human health.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.001 |
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.
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".