Genetic Perturbation of Redox Status and Fructose-Supported Elevation of Dark Anaerobic Hydrogen Evolution in Synechocystis sp. Strain PCC 6803
Bibliographic record
Abstract
The effects of fructose on the dark anaerobic hydrogen production of the genetically modified mutants from glucose tolerant derivative of unicellular cyanobacterium Synechocystis sp. strain PCC 6803 (GT strain) in nitrate-free buffer solution has been studied by following the time courses of the amounts of hydrogen, fructose, dry cell weight, lactate and acetate per culture volume and the amount of endogenous glucose per dry cell weight. Considering that hydrogen production on bidirectional NiFe-hydrogenase competes NAD(P)H with lactate dehydrogenase and alcohol dehydrogenase, mutants which lack lactate dehydrogenase (Dddh mutant) and both lactate dehydrogenase and alcohol dehydrogenase (DadhDddh mutant), were utilized. These genetic modifications have a high potential to redirect electrons to NiFe-hydrogenase for hydrogen generation. A supply of additive to increase electron supply has found to be a successful method to activate hydrogen production. Fructose was selected as an additive due to our previous observation that hydrogen production in GT strain was highly increased in the presence of 50 mmol mL-1 fructose. Initial hydrogen production rate of DadhDddh mutant in the presence of 50 mmol mL-1 fructose was increased to 0.129 mmol mL-1h -1 that was 5.11 times that of GT strain. This increase was associated with the initial increase in glucose accumulation rate. Hydrogen production by DadhDddh mutant in the presence of 50 mmol mL-1 fructose was quite stable for at least 120 h. Fructose-mediated hydrogen production resulted in an 11-fold increase in the moles of hydrogen per culture volume at 120 h over controls.
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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 | 0.000 | 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".