Novel extracellular proteolytic activity in<i>Pediococcus acidilactici</i>ATCC 8042
Bibliographic record
Abstract
Proteolytic systems are common in lactic acid bacteria, but there are few reports about proteases or peptidases in the genus Pediococcus. To evaluate the presence of these types of enzymes, Pediococcus acidilactici ATCC 8042 was cultured in MRS broth. Supernatants collected during the log phase showed proteolytic activity towards an elastin dispersion when assayed using a spectrophotometer. Zn2+ showed a stimulatory effect, and the proteolytic activity reached its maximum when 200 mmol/L NaCl was included in the reaction buffer. On the other hand, activity was reduced when 5 mmol/L EDTA, 10 mmol/L phenylmethylsulfonyl fluoride, and 10 mmol/L 1,10-phenanthroline were used or when the sample was heat treated. Zymograms showed two different proteolytic bands when gelatin was used as a substrate (>200 and 107 kDa), but only the higher molecular mass band was detected when casein or elastin was used. The gelatinolytic activity was not detected with zymograms of the 107 kDa band, which was the one inactivated by heat treatment. The use of a renaturing SDS-PAGE gel with embedded Micrococcus lysodeikticus cells allowed for the detection of a band with peptidoglycan hydrolase activity migrating at about 110 kDa. This activity was lost when 10 mmol/L EDTA was added to the renaturing buffer. Therefore, Pediococcus showed at least three different extracellular enzymes that were produced during the logarithmic growth phase and acted on peptide substrates. Each showed different substrate specificity, ion requirements, and thermostability.
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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 | 0.000 |
| 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".