Characterization of an Alternative Starch Utilization System from the Human Gut Bacterium <i>Bacteroides thetaiotaomicron</i> and its Implications in Human Nutrition
Bibliographic record
Abstract
Bacteroides thetaiotaomicron is a dominant member of the human gut microbiota and has been shown to play an important role in the physiological state of the human body with influences on nutrition, pathology and immunological development. This bacterium has been recorded to have an extensive array of genes involved in the acquisition and utilization of dietary and human mucosal glycans. The ability to utilization such dietary carbohydrates were first recognized with the Starch Utilization System (Sus) and demonstrated an important metabolic cascade that allows B.thetaiotaomicron to thrive in the gut. The objective of our study is to investigate an additional starch system in B.thetaiotaomicron and critically analyze its contribution to starch utilization in the human colon. This system is predicted to function similarly to Sus with outer membrane binding of starch glycans by a SusD‐homolog, transportation of glycans into the bacterial cell by a SusC‐homolog, periplasmic hydrolysis by a GH31 and GH97 glycoside hydrolases and gene up‐regulation by a Two‐Component System regulator. Using biochemical techniques, our research has demonstrated for the first time that a SusD homolog has the ability to hydrolyze starch glycans outside the cell and assist in the utilization of starch as an energy source. Furthermore, through biochemical and structural studies, we are able to show maltooligosaccharide hydrolysis from a GH31 enzyme, complemented with a GH 97 enzyme, revealing dual alpha‐glucosidic activity in the periplasm. These mechanisms demonstrate a divergence of starch utilization and further provide supporting evidence of the evolutionary advantage this bacterium has in the human colon.
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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 | 0.000 | 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) | 0.000 | 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".