Production and characterization of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymers from a pre- fermented hardwood hydrolysate
Bibliographic record
Abstract
Abstract Economically viable production of poly(3-hydoxybutyrate- co -3-hydroxyvalerate) (PHBV) copolymers remains a challenge. The objective of this work was to produce low-cost PHBV copolymers from lignocellulose-derived mixed sugars without genetic engineering or addition of chemical precursors. A hardwood hydrolysate was first pre-fermented using the facultative anaerobe Propionibacterium acidipropionici, and the resulting propionate-rich effluent was used for subsequent PHBV biosynthesis in Paraburkholderia sacchari or Hydrogenophaga pseudoflava . P. acidipropionici displayed a high tolerance to the hardwood hydrolysate and produced up to 11 g L −1 propionate (with varying amounts of lactate and acetate) under batch conditions. Propionic acid exerted significant toxicity toward P. sacchari and H. pseudoflava , so dilution of the pre-fermentation effluent was required prior to the PHBV production step. When P. sacchari and H. pseudoflava were grown on the pre-fermented mixture of glucose, xylose, lactate, acetate, and propionate (diluted to 15 mM propionate), the organic acids were consumed preferentially. H. pseudoflava accumulated up to 41.7 ± 7.0% cell dry mass (CDM) as PHBV that contained 13.7 ± 2.4 mol % 3-HV subunits. Meanwhile, P. sacchari accumulated up to 56.0 ± 5.8% CDM as PHA, but with lower 3-HV contents (1.2–5.1%). The PHBV copolymers resulting from this integrated process showed a desirable crystallinity, but the molecular weights were lower and the melt temperatures were higher than expected in all cases. Future work should focus on tuning the cultivation parameters to target higher molecular weight polymers while designing a feeding strategy of the pre-fermented stream that circumvents toxicity issues and allows a better control of the formation of random vs . block copolymers. Graphical abstract
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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 | 0.000 | 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 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".