Diversity within the genus Thermoanaerobacter and its potential implications in lignocellulosic biofuel production through consolidated bioprocessing
Bibliographic record
Abstract
A major obstacle to achieving commercially viable lignocellulosic biofuels through consolidated bioprocessing (CBP) is the lack of “industry-ready” microorganisms. Ideally, a CBP-relevant organism would achieve efficient and complete hydrolysis of lignocellulose, simultaneous utilization of the diverse hydrolysis products and high yields of the desired biofuel. To date, no single microbe has been identified that can perform all of these processes at industrially significant levels. As such, thermophilic decaying woodchip compost was investigated as a source of novel lignocellulolytic, biofuel producing bacteria. From a single sample, a collection of physiologically diverse strains were isolated, which displayed differences in substrate utilization and biofuel production capabilities. Molecular characterization of these isolates, and development of a genome relatedness prediction model based on the chaperonin-60 universal target sequence, identified these isolates as strains of Thermoanaerobacter thermohydrosulfuricus. Application of this model to other Thermoanaerobacter spp. further identified that these isolates belong to a divergent and lesser characterized lineage within the genus. Based on this, the CBP-potential of a single isolate, T. thermohydrosulfuricus WC1, was selected for further investigation through metabolic, genomic and proteomic analyses. Its ability to grow on polymeric xylan, potentially catalyzed by an endoxylanase found in only a few Thermoanaerobacter strains, distinguishes T. thermohydrosulfuricus WC1 from many other strains within the genus. The simultaneous consumption of two important lignocellulose constituent saccharides, cellobiose and xylose was also observed and represents a desirable phenotype in CBP-relevant organisms. However, at elevated sugar concentrations, T. thermohydrosulfuricus WC1 produces principally lactate, rather than the desired biofuel ethanol, as the major end-product. Proteomic analysis identified that all likely end-product forming proteins were expressed at high levels suggesting that the end-product distribution patterns in T. thermohydrosulfuricus WC1 are likely controlled via metabolite-based regulation or are constrained by metabolic bottlenecks. The xylanolytic and simultaneous substrate utilization capabilities of T. thermohydrosulfuricus WC1 identify it as a strain of interest for CBP. However, for its development into an “industry-ready” strain as a co-culture with a cellulolytic microorganism, improved biofuel producing capabilities are needed. The practical implications of CBP-relevant phenotypes in T. thermohydrosulfuricus WC1 in relation to other Thermoanaerobacter spp. will be discussed.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| 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".