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- Getting another organism to take away the byproducts that hinder hydrogen production
- combining dark fermentation and photo fermentation - Combined fermentation
- getting an organism to consume the acetate
- containment - making the bacteria dependent on each other to survive
- syntrophic exchange (http://www.pnas.org/content/111/20/E2149.short?rss=1)
- down-regulate the pathways except for the hydrogen production pathway
- protein scaffolding to increase metabolic flux
- making recombinant proteins
- one bacteria degrading proteins/complex sugars that the other can use for production (http://www.sciencedirect.com.ezproxyberklee.flo.org/science/article/pii/S0960852414017301)
- metabolic wiring: bacteria in a closed system produce molecules that regulate the growth of the other bacteria http://2014.igem.org/Team:Edinburgh/project/population
- co-culture of anaerobic thermophiles producing Hydrogen: http://www.sciencedirect.com.ezproxyberklee.flo.org/science/article/pii/S0360319908003844
Engineering a Synthetic Dual-Organism System for Hydrogen Production - http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2663214/
conversion of biomass into formate, which can subsequently be processed into hydrogen by Escherichia coli.
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| Organism | Domain | T opt (°C) | Cultivation | Substrate | Y H2 mmol/mmol C6 | Gram positive or negative? (AHL) | References |
|---|---|---|---|---|---|---|---|
| Thermobrachium celere | Bacteria | 67 | Batch | Glucose | 3.36 | gram positive | (Ciranna et al. 2011) |
| Clostridium stercorarium DSM 2910 | Bacteria | 58 | Continuous | Lactose | 1.57 | (Collet et al. 2004) | |
| Thermovorax subterraneus | Bacteria | 70 | Batch | Glucose | 1.4 | gram positive | (Mäkinen et al. 2009) |
Metabolic features of thermophilic hydrogen producers (modified and continued from Chou et al. 2008)
| Organism | Fermentability of feedstocks/polymers | CCR | Auxotrophy to amino acids | Electron carriers | Hydrogenasea | Reductant sink | References |
|---|---|---|---|---|---|---|---|
| Clostridia (Cl. thermocellum) | Starch, cellulose, lignocellulose | Yes | No | NADH, ferredoxin | Uptake, Fe-only, FNOR | Alcohol, organic acids, lactate | Johnson et al. (1981), Desvaux (2006) |
| Thermococcales(Pyroccus furiosus) | Maltose, cellobiose, β-glucans, starch | No | Yes | Ferredoxin | MBH, NiFe-only, FNOR | Alanine, ethanol | Hoaki et al. (1994), Maeder et al. (1999), Silva et al. (2000), Robb et al. (2001) |
| Thermotogales (T. maritima/T. neapolitana) | Cellulose, xylan, starch, cellobiose, lignocellulose | Yes | No | NADH, ferredoxin | Fe-only, NMOR, FNOR | Lactate, alanine | Schönheit and Schäfer (1995), Vargas and Noll (1996), Rinker and Kelly (2000), Bonch-Osmolovskaya (2001) |
| Caldicellulosiruptor(C. saccharolyticus) | Cellulose (avicel, amorp.), xylan, pectin, α-glucan, β-glucan, lignocellulose, guargum | No | No | NADH, ferredoxin | Fe-only, NiFe-only | Lactate, ethanol | Rainey et al. (1994), de Vrije et al. (2007), van de Werken et al. (2008), Ivanova et al. (2008), Willquist and van Niel (2012) |
| Thermoanaerobacter(T. tengcongensis MB4) | Starch, sucrose, glycerol | Yes | Yes | NADH, Ferredoxin | Fe-only, NiFe-only | Ethanol | Xue et al. (2001), Warner and Lolkema (2003), Soboh et al. (2004) |
CCR carbon catabolite repression
aTypes of hydrogenases—uptake, NiFe type hydrogen uptake hydrogenase, FNOR (ferredoxin:NAD(P)H oxidoreductase), Fe-only, Fe-only evolution hydrogenase, NiFe-only, NiFe-only evolution hydrogenase, NMOR (NADH:methylviologen oxidoreductase) and MBH (membrane-bound hydrogenase)
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