High-Level Bio-Based Production of Coproporphyrin in Escherichia coli
Bibliographic record
Abstract
This study reports on the development of effective strain engineering strategies for the high-level bio-based production of coproporphyrin (CP), a porphyrin pigment compound with various applications, using Escherichia coli as a production host. Our approach involves heterologous implementation of the Shemin/C4 pathway in an E. coli host strain with an enlarged intracellular pool of succinyl-CoA. To regulate the expression of the key pathway genes, including hemA/B/D/E/Y, we employed a plasmid system comprising two operons regulated by strong trc and gracmax promoters, respectively. Using the engineered E. coli strains for bioreactor cultivation under aerobic conditions with glycerol as the carbon source, we produced up to 353 mg/L CP with minimal byproduct formation. The overproduced CP was secreted extracellularly, posing minimal physiological toxicity and impact on the producing cells. To date, targeted bio-based production of CP by E. coli has yet to be reported. In addition to the demonstration of high-level bio-based production of CP, our study underscores the importance of identifying key enzymatic reactions limiting the overall metabolite production for developing differential expression strategies for pathway modulation and even optimization. This investigation paves the way for the development of effective metabolic engineering strategies based on targeted manipulation of key enzymes to customize engineered strains for effective large-scale bio-based production.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".