Transcriptomic and metabolomic responses to carbon and nitrogen sources in <i>Methylomicrobium album BG8</i>
Bibliographic record
Abstract
ABSTRACT Methanotrophs use methane as their sole carbon and energy source and represent an attractive platform for converting single-carbon feedstocks into value-added compounds. Optimizing these species for biotechnological applications involves choosing an optimal growth substrate based on an understanding of cellular responses to different nutrients. Although many studies of methanotrophs have examined growth rate, yield, and central carbon flux in cultures grown with different carbon and nitrogen sources, few studies have examined more global cellular responses to different media. Here, we evaluated global transcriptomic and metabolomic profiles of Methylomicrobium album BG8 when grown with methane or methanol as the carbon source and nitrate or ammonium as the nitrogen source. We identified five key physiological changes during growth on methanol: M. album BG8 cultures upregulated transcripts for the Entner-Doudoroff and pentose phosphate pathways for sugar catabolism, produced more ribosomes, remodeled its phospholipid membrane, activated various stress response systems, and upregulated glutathione-dependent formaldehyde detoxification. When using ammonium, M. album BG8 upregulated haoAB hydroxylamine dehydrogenase and the overall central metabolic activity; whereas when using nitrate, cultures upregulated genes for nitrate assimilation and conversion. Overall, we identified several nutrient source-specific responses that could provide a valuable basis for future research on the biotechnological optimization of these species. IMPORTANCE Methanotrophs are gaining increasing interest for their biotechnological potential to convert single-carbon compounds into value-added products such as industrial chemicals, fuels, and bioplastics. Optimizing these species for biotechnological applications requires a detailed understanding of how cellular activity and metabolism varies across different growth substrates. Although each of the two most commonly used carbon sources (methane or methanol) and nitrogen sources (ammonium or nitrate) in methanotroph growth media have well-described advantages and disadvantages in an industrial context, their effects on global cellular activity remain poorly characterized. Here, we comprehensively describe the transcriptomic and metabolomic changes that characterize the growth of an industrially promising methanotroph strain on multiple combinations of carbon and nitrogen sources. Our results represent a more holistic evaluation of cellular activity than previous studies of core metabolic pathways and provide a valuable basis for the future biotechnological optimization of these species.
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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 | 0.001 |
| 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".