Transcriptional activity and role of plasmids of <em>Lactobacillus brevis </em>BSO 464 and <em>Pediococcus claussenii </em>ATCC BAA-344T during growth in the presence of hops
Bibliographic record
Abstract
Whole-transcriptome analysis was performed on beer-spoilage organisms<em> Lactobacillus brevis </em>BSO 464 (Lb464) and <em>Pediococcus claussenii </em>ATCC BAA-344<sup>T</sup> (Pc344) when grown in growth-limiting concentrations of hop extract. This was done to delineate the hops-specific component of the total transcriptional response for these bacteria when growing in beer. The transcriptome of highly hop-tolerant isolate Lb464 had fewer genes with differential expression in response to a stronger challenge (i.e., higher bitterness units) of hop extract than did Pc344, highlighting the variable nature of hop-tolerance in beer-spoilage-related lactic acid bacteria. As Lb464 can grow in pressurized/gassed beer and Pc344 cannot, this indicates that the genetic and physiological response to hops alone does not dictate the overall beer-spoilage virulence of an isolate. The general response to hops in both isolates involves pathways of acid tolerance and intracellular pH homeostasis, with glutamate and citrate metabolism, and biogenic amine metabolism as additional major responses to the presence of hop extract by Lb464 and Pc344, respectively. A Pc344 chromosomal ABC transporter (PECL_1630) was more strongly expressed than the plasmid-located, hop-tolerance ABC transporter <em>horA.</em> PECL_1630 is suggested to be involved in import of ATP into the cell, potentially assisting the total bacterial community when facing hop stress. This transporter is found in other beer-related <em>P. claussenii </em>suggesting a putative species-specific beer-spoilage-related genetic marker. Lb464 and Pc344 each contain eight plasmids and transcription from almost all occurs in response to both hops and beer. However, as evident by both transcriptional analysis and plasmid variant analysis, each bacterium harbors one plasmid that is critical for responding to hops and beer stress. For both bacteria, complex transcriptional regulation and cooperation between chromosomal and plasmid-based genes occurs in response to the growth challenges imposed by hops or beer.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 teacher head, 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".