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Molecular structure of photosynthetic microbial biofuels for improved engine combustion and emissions characteristics.

Hellier P, Purton S, Ladommatos N - Front Bioeng Biotechnol (2015)

Bottom Line: These can be significantly more sustainable, throughout the production-to-consumption lifecycle, than the fossil fuels and crop-based biofuels they might replace.Furthermore, these fuel molecules can be designed for higher efficiency of energy release and lower exhaust emissions during combustion.This paper presents a review of potential fuel molecules from photosynthetic microbes and the performance of these possible fuels in modern internal combustion engines, highlighting which modifications to the molecular structure of such fuels may enhance their suitability for specific combustion regimes.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, University College London , London , UK.

ABSTRACT
The metabolic engineering of photosynthetic microbes for production of novel hydrocarbons presents an opportunity for development of advanced designer biofuels. These can be significantly more sustainable, throughout the production-to-consumption lifecycle, than the fossil fuels and crop-based biofuels they might replace. Current biofuels, such as bioethanol and fatty acid methyl esters, have been developed primarily as drop-in replacements for existing fossil fuels, based on their physical properties and autoignition characteristics under specific combustion regimes. However, advances in the genetic engineering of microalgae and cyanobacteria, and the application of synthetic biology approaches offer the potential of designer strains capable of producing hydrocarbons and oxygenates with specific molecular structures. Furthermore, these fuel molecules can be designed for higher efficiency of energy release and lower exhaust emissions during combustion. This paper presents a review of potential fuel molecules from photosynthetic microbes and the performance of these possible fuels in modern internal combustion engines, highlighting which modifications to the molecular structure of such fuels may enhance their suitability for specific combustion regimes.

No MeSH data available.


Pyruvate relevant metabolic pathways in Synechocystis sp. PCC6803. ackA, acetate kinase; acs, acetyl-coenzyme A synthetase; AlaDH, alanine dehydrogenase; ADH, alcohol dehydrogenase; agp, ADP-glucose pyrophosphorylase; glg, glycogen synthase; AldDH, acetaldehyde dehydrogenase; me, malic enzyme; PDC, pyruvate decarboxylase; pps, phosphoenolpyruvate synthase; ldh, lactate dehydrogenase; phaA, PHA-specific β-ketothiolase; phaB, PHA-specific acetoacetyl-CoA reductase; pta, phosphotransacetylase; pyk, pyruvate kinase; Rubisco, ribulose-1,5-bisphosphate carboxylase/oxygenase. Redrawn from Gao et al. (2012) with permission from The Royal Society of Chemistry.
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Figure 3: Pyruvate relevant metabolic pathways in Synechocystis sp. PCC6803. ackA, acetate kinase; acs, acetyl-coenzyme A synthetase; AlaDH, alanine dehydrogenase; ADH, alcohol dehydrogenase; agp, ADP-glucose pyrophosphorylase; glg, glycogen synthase; AldDH, acetaldehyde dehydrogenase; me, malic enzyme; PDC, pyruvate decarboxylase; pps, phosphoenolpyruvate synthase; ldh, lactate dehydrogenase; phaA, PHA-specific β-ketothiolase; phaB, PHA-specific acetoacetyl-CoA reductase; pta, phosphotransacetylase; pyk, pyruvate kinase; Rubisco, ribulose-1,5-bisphosphate carboxylase/oxygenase. Redrawn from Gao et al. (2012) with permission from The Royal Society of Chemistry.

Mentions: The direct production of ethanol through light-driven CO2 fixation by cyanobacteria (as opposed to the traditional method of fermentation of sugars by heterotrophic microbes) has been reported by several researchers (Deng and Coleman, 1999; Dexter and Fu, 2009; Gao et al., 2012). The strategy involves the introduction of genes for pyruvate decarboxylase and alcohol dehydrogenase to convert pyruvate to ethanol, as shown in Figure 3. Deng and Coleman (1999) introduced gene sequences from the bacterium Zymomonas mobilis into Synechococcus elongatus, which resulted in ethanol production and its subsequent diffusion from the cells to the culture medium. More recently, both Dexter and Fu (2009) and Gao et al. (2012) integrated sequences from Zymomonas mobilis into Synechocystis PCC 6803 for ethanol production via that of acetaldehyde, as shown in Figure 2, with a final ethanol concentration of 5.5 g/L after a cultivation period of 26 days reported by the latter (Gao et al., 2012). Several companies including Alginol in the USA1 and Photanol in the Netherlands2 are currently commercializing such technology.


Molecular structure of photosynthetic microbial biofuels for improved engine combustion and emissions characteristics.

Hellier P, Purton S, Ladommatos N - Front Bioeng Biotechnol (2015)

Pyruvate relevant metabolic pathways in Synechocystis sp. PCC6803. ackA, acetate kinase; acs, acetyl-coenzyme A synthetase; AlaDH, alanine dehydrogenase; ADH, alcohol dehydrogenase; agp, ADP-glucose pyrophosphorylase; glg, glycogen synthase; AldDH, acetaldehyde dehydrogenase; me, malic enzyme; PDC, pyruvate decarboxylase; pps, phosphoenolpyruvate synthase; ldh, lactate dehydrogenase; phaA, PHA-specific β-ketothiolase; phaB, PHA-specific acetoacetyl-CoA reductase; pta, phosphotransacetylase; pyk, pyruvate kinase; Rubisco, ribulose-1,5-bisphosphate carboxylase/oxygenase. Redrawn from Gao et al. (2012) with permission from The Royal Society of Chemistry.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4403606&req=5

Figure 3: Pyruvate relevant metabolic pathways in Synechocystis sp. PCC6803. ackA, acetate kinase; acs, acetyl-coenzyme A synthetase; AlaDH, alanine dehydrogenase; ADH, alcohol dehydrogenase; agp, ADP-glucose pyrophosphorylase; glg, glycogen synthase; AldDH, acetaldehyde dehydrogenase; me, malic enzyme; PDC, pyruvate decarboxylase; pps, phosphoenolpyruvate synthase; ldh, lactate dehydrogenase; phaA, PHA-specific β-ketothiolase; phaB, PHA-specific acetoacetyl-CoA reductase; pta, phosphotransacetylase; pyk, pyruvate kinase; Rubisco, ribulose-1,5-bisphosphate carboxylase/oxygenase. Redrawn from Gao et al. (2012) with permission from The Royal Society of Chemistry.
Mentions: The direct production of ethanol through light-driven CO2 fixation by cyanobacteria (as opposed to the traditional method of fermentation of sugars by heterotrophic microbes) has been reported by several researchers (Deng and Coleman, 1999; Dexter and Fu, 2009; Gao et al., 2012). The strategy involves the introduction of genes for pyruvate decarboxylase and alcohol dehydrogenase to convert pyruvate to ethanol, as shown in Figure 3. Deng and Coleman (1999) introduced gene sequences from the bacterium Zymomonas mobilis into Synechococcus elongatus, which resulted in ethanol production and its subsequent diffusion from the cells to the culture medium. More recently, both Dexter and Fu (2009) and Gao et al. (2012) integrated sequences from Zymomonas mobilis into Synechocystis PCC 6803 for ethanol production via that of acetaldehyde, as shown in Figure 2, with a final ethanol concentration of 5.5 g/L after a cultivation period of 26 days reported by the latter (Gao et al., 2012). Several companies including Alginol in the USA1 and Photanol in the Netherlands2 are currently commercializing such technology.

Bottom Line: These can be significantly more sustainable, throughout the production-to-consumption lifecycle, than the fossil fuels and crop-based biofuels they might replace.Furthermore, these fuel molecules can be designed for higher efficiency of energy release and lower exhaust emissions during combustion.This paper presents a review of potential fuel molecules from photosynthetic microbes and the performance of these possible fuels in modern internal combustion engines, highlighting which modifications to the molecular structure of such fuels may enhance their suitability for specific combustion regimes.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, University College London , London , UK.

ABSTRACT
The metabolic engineering of photosynthetic microbes for production of novel hydrocarbons presents an opportunity for development of advanced designer biofuels. These can be significantly more sustainable, throughout the production-to-consumption lifecycle, than the fossil fuels and crop-based biofuels they might replace. Current biofuels, such as bioethanol and fatty acid methyl esters, have been developed primarily as drop-in replacements for existing fossil fuels, based on their physical properties and autoignition characteristics under specific combustion regimes. However, advances in the genetic engineering of microalgae and cyanobacteria, and the application of synthetic biology approaches offer the potential of designer strains capable of producing hydrocarbons and oxygenates with specific molecular structures. Furthermore, these fuel molecules can be designed for higher efficiency of energy release and lower exhaust emissions during combustion. This paper presents a review of potential fuel molecules from photosynthetic microbes and the performance of these possible fuels in modern internal combustion engines, highlighting which modifications to the molecular structure of such fuels may enhance their suitability for specific combustion regimes.

No MeSH data available.