Hydrogen production during fermentation of cellulose by the thermophilic bacterium Clostridium thermocellum
Bibliographic record
Abstract
Biohydrogen production from cellulosic waste materials using dark fermentation is a promising technology for producing renewable energy.The purpose of this study was to evaluate residual cellulosic materials generated from local sources for their H2 production potential and to charactenze growth of Clostridìum thermocellum, during fermentation of a cellulosic substrate under continuous culture conditions.C. thermocellumATcc 27405, is a cellulolytic, thermophilic bacterium that has been shown to be capable of Hz production on both cellobiose and cellulosic substrates.The complex cellulosic materials tested were dried distillers grain (DDGs), barley hulls (BH) and.Fusarium head.blight contaminated barley hulls (CBH)' Several simultaneous batch fermentation experiments were conducted in order to quantiSr H2 production, and to determine soluble end-product synthesis pattems.overall, the dried distillers grain produced the highest concentration of hydrogen gas at 1.27 mmol H2lglucose equivalent utilized.cBH and BH produced 1.1g and 1.24 mmol H2lglucose equivalent utilized, respectively.overall, this study indicates that hydrogen derived from a variety of cellulosic waste biomass sources is a possible candidate for the development of sustainable energy.Continuous hydrogen (H2) production during fermentation of g-cellulose was established using a 5 L fermentor.Growth experiments \¡/ere maintained for over 3000 hours.Substrate concentrations varied between I to 4 g L-1.Continuous sparging with nitrogen gas was used to prevent clogging of the feed-line.The pH and temperature of the reactor were maintained throughout the experiment.At concentrations above 4 g L-1, the delivery of cr-cellulose was impaired due to feedline clogging and it became difficult to maintain a homogenous suspension.The highest total gas (H2 plus CO2) production rate, 56.6 ml I;r hr-I, was observed at a dilution rate of 0.042h-1 and substrate concentration of 4 g L l.Under these conditions, the H2 production rate was 5.06 mmol hr-I.Acetate and ethanol were the major soluble end-products, while lactate and formate \¡¡ere greatly reduced compared to production in batch cultures.Concentations of all metabolites increased with increasing substrate concentration, with the exception of lactate.This data has increased knowledge of
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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) | 0.001 | 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".