Trash to treasure: production of biofuels and commodity chemicals via syngas fermenting microorganisms

Latif, Haythem; Zeidan, Ahmad A.; Nielsen, Alex Toftgaard; Zengler, Karsten

doi:10.1016/j.copbio.2013.12.001

Cited by 177 publications

(133 citation statements)

References 80 publications

(93 reference statements)

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“…industrial waste gases, syngas (CO/CO 2 and H 2 ) and methane (Bertsch and Müller, 2015;Daniell et al, 2012;Dürre and Eikmanns, 2015;Köpke et al, 2011;Latif et al, 2014;Liew et al, 2016b). Production of fuels and chemicals via gas fermentation does not compete for arable land and food resources, in contrast to using farmed sugars as feedstock.…”

Section: Introductionmentioning

confidence: 99%

Arginine deiminase pathway provides ATP and boosts growth of the gas-fermenting acetogen Clostridium autoethanogenum

Valgepea

Loi

Behrendorff

et al. 2017

Metabolic Engineering

100

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Arginine deiminase pathway provides ATP and boosts growth of the gas-fermenting acetogen Clostridium autoethanogenum Metabolic Engineering, http://dx.doi.org/10.1016Engineering, http://dx.doi.org/10. /j.ymben.2017 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractAcetogens are attractive organisms for the production of chemicals and fuels from inexpensive and non-food feedstocks such as syngas (CO, CO 2 and H 2 ). Expanding their product spectrum beyond native compounds is dictated by energetics, particularly ATP availability. Acetogens have evolved sophisticated strategies to conserve energy from reduction potential differences between major redox couples, however, this coupling is sensitive to small changes in thermodynamic equilibria. To accelerate the development of strains for energy-intensive products from gases, we used a genome-scale metabolic model (GEM) to explore alternative ATP-generating pathways in the gas-fermenting acetogen 1 Present address: Department of Plant and Environmental Science, University of Copenhagen, Copenhagen, Denmark Clostridium autoethanogenum. Shadow price analysis revealed a preference of C.autoethanogenum for nine amino acids. This prediction was experimentally confirmed under heterotrophic conditions. Subsequent in silico simulations identified arginine (ARG) as a key enhancer for growth. Predictions were experimentally validated, and faster growth was measured in media containing ARG (t D~4 h) compared to growth on yeast extract (t D~9 h). The growth-boosting effect of ARG was confirmed during autotrophic growth.Metabolic modelling and experiments showed that acetate production is nearly abolished and fast growth is realised by a three-fold increase in ATP production through the arginine deiminase (ADI) pathway. The involvement of the ADI pathway was confirmed by metabolomics and RNA-sequencing which revealed a ~500-fold up-regulation of the ADI pathway with an unexpected down-regulation of the Wood-Ljungdahl pathway. The data presented here offer a potential route for supplying cells with ATP, while demonstrating the usefulness of metabolic modelling for the discovery of native pathways for stimulating growth or enhancing energy availability.

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Section: Introductionmentioning

confidence: 99%

Arginine deiminase pathway provides ATP and boosts growth of the gas-fermenting acetogen Clostridium autoethanogenum

Valgepea

Loi

Behrendorff

et al. 2017

Metabolic Engineering

100

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“…Syngas reforming, tar cracking and water gas shift reaction are some of the current techniques used to adjust the H 2 /CO ratio of syngas from gasification [11,12]. This gaseous fuel can be used to generate heat in boilers, electricity in turbines, hydrocarbons via Fischer-Tropsch processes and ethanol through biological conversion [13][14][15]. There are a wide number of biomass gasification technologies that are designed to process different feedstock; fixed bed and fluidized bed gasifiers are the two major categories [16].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Biomass Physical Properties on Top-Lit Updraft Gasification of Woodchips

2016

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Abstract:The performance of a top-lit updraft gasifier affected by biomass (pine wood) particle size, moisture content and compactness was studied in terms of the biochar yield, biomass burning rate, syngas composition and tar content. The highest biochar yield increase (from 12.2% to 21.8%) was achieved by varying the particle size from 7 to 30 mm, however, larger particles triggered tar generation that reached its maximum of 93.5 g/m 3 syngas at 30-mm biomass particles; in contrast, the hydrogen content in syngas was at its minimum of 2.89% at this condition. The increase in moisture content from 10% to 22% reduced biochar yield from 12% to 9.9%. It also reduced the tar content from 12.9 to 6.2 g/m 3 which was found to be the lowest range of tar content in this work. Similarly, the carbon monoxide composition in syngas decreased to its minimum of 11.16% at moisture content of 22%. Finally, the biomass compactness increased biochar yield up to 17% when the packing mass was 3 kg. However, the addition of compactness also increased the tar content in syngas, but little effect was noticed in syngas composition.

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“…Gas fermentation by acetogenic bacteria (acetogens) is a promising alternative route for producing chemicals and biofuels (3)(4)(5). Acetogens are obligate anaerobes that use the Wood-Ljungdahl pathway to synthesize acetyl-coenzyme A (acetyl-CoA) by reducing CO and/or CO 2 plus H 2 (6,7).…”

mentioning

confidence: 99%

Reconstruction of an Acetogenic 2,3-Butanediol Pathway Involving a Novel NADPH-Dependent Primary-Secondary Alcohol Dehydrogenase

Köpke

Gerth

Maddock

et al. 2014

Appl Environ Microbiol

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bAcetogenic bacteria use CO and/or CO 2 plus H 2 as their sole carbon and energy sources. Fermentation processes with these organisms hold promise for producing chemicals and biofuels from abundant waste gas feedstocks while simultaneously reducing industrial greenhouse gas emissions. The acetogen Clostridium autoethanogenum is known to synthesize the pyruvate-derived metabolites lactate and 2,3-butanediol during gas fermentation. Industrially, 2,3-butanediol is valuable for chemical production.Here we identify and characterize the C. autoethanogenum enzymes for lactate and 2,3-butanediol biosynthesis. The putative C. autoethanogenum lactate dehydrogenase was active when expressed in Escherichia coli. The 2,3-butanediol pathway was reconstituted in E. coli by cloning and expressing the candidate genes for acetolactate synthase, acetolactate decarboxylase, and 2,3-butanediol dehydrogenase. Under anaerobic conditions, the resulting E. coli strain produced 1.1 ؎ 0.2 mM 2R,3R-butanediol (23 M h ؊1 optical density unit ؊1 ), which is comparable to the level produced by C. autoethanogenum during growth on COcontaining waste gases. In addition to the 2,3-butanediol dehydrogenase, we identified a strictly NADPH-dependent primarysecondary alcohol dehydrogenase (CaADH) that could reduce acetoin to 2,3-butanediol. Detailed kinetic analysis revealed that CaADH accepts a range of 2-, 3-, and 4-carbon substrates, including the nonphysiological ketones acetone and butanone. The high activity of CaADH toward acetone led us to predict, and confirm experimentally, that C. autoethanogenum can act as a whole-cell biocatalyst for converting exogenous acetone to isopropanol. Together, our results functionally validate the 2,3-butanediol pathway from C. autoethanogenum, identify CaADH as a target for further engineering, and demonstrate the potential of C. autoethanogenum as a platform for sustainable chemical production.

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Trash to treasure: production of biofuels and commodity chemicals via syngas fermenting microorganisms

Cited by 177 publications

References 80 publications

Arginine deiminase pathway provides ATP and boosts growth of the gas-fermenting acetogen Clostridium autoethanogenum

Arginine deiminase pathway provides ATP and boosts growth of the gas-fermenting acetogen Clostridium autoethanogenum

The Effect of Biomass Physical Properties on Top-Lit Updraft Gasification of Woodchips

Reconstruction of an Acetogenic 2,3-Butanediol Pathway Involving a Novel NADPH-Dependent Primary-Secondary Alcohol Dehydrogenase

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