Capnophilic lactic fermentation and hydrogen synthesis by Thermotoga neapolitana: An unexpected deviation from the dark fermentation model

Dipasquale, Laura; d’Ippolito, Giuliana; Fontana, Angelo

doi:10.1016/j.ijhydene.2013.12.183

Cited by 38 publications

(54 citation statements)

References 14 publications

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“…Traditionally, lactic acid is produced by homolactic fermentation processes using pure cultures of lactic acid bacteria belonging to the genus Lactobacillus [5]. Recently, a heterolactic fermentation process with a new metabolic pathway named capnophilic (CO 2 -led) lactic fermentation (CLF) was found to be present in the hyperthermophilic marine bacterium Thermotoga neapolitana [6]. Under CLF conditions, both hydrogen and lactic acid are synthesized simultaneously unlike in the classic dark fermentation processes [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, a heterolactic fermentation process with a new metabolic pathway named capnophilic (CO 2 -led) lactic fermentation (CLF) was found to be present in the hyperthermophilic marine bacterium Thermotoga neapolitana [6]. Under CLF conditions, both hydrogen and lactic acid are synthesized simultaneously unlike in the classic dark fermentation processes [6][7][8][9]. T. neapolitana fermentation takes place on a wide range of carbohydrate-rich substrates at 80 • C (353.15 K) and pH 6.5.…”

Section: Introductionmentioning

confidence: 99%

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Adsorption Behaviour of Lactic Acid on Granular Activated Carbon and Anionic Resins: Thermodynamics, Isotherms and Kinetic Studies

et al. 2017

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Solid-liquid extraction (adsorption or ion exchange) is a promising approach for the in situ separation of organic acids from fermentation broths. In this study, a diluted concentration of lactic acid (<10 g/L) separation from a model fermentation broth by granular activated carbon (GAC) as well as weak (Reillex ® 425 or RLX425) and strong (Amberlite ® IRA-400 or AMB400) base anion exchange resins under various operating conditions was experimentally investigated. Thermodynamic analysis showed that the best lactic acid adsorption performances were obtained at a pH below the pK a value of lactic acid (i.e., 3.86) for GAC and RLX425 by physical adsorption mechanism and above the pK a value for the AMB400 resin by an ion exchange mechanism, respectively. The adsorption capacity for GAC (38.2 mg/g) was the highest, followed by AMB400 (31.2 mg/g) and RLX425 (17.2 mg/g). As per the thermodynamic analysis, the lactic acid adsorbed onto GAC and RLX425 through a physical adsorption mechanism, whereas the lactic acid adsorbed onto AMB400 with an ion exchange mechanism. The Langmuir adsorption isotherm model (R 2 > 0.96) and the pseudo-second order kinetic model (R 2~1 ) fitted better to the experimental data than the other models tested. Postulating the conditions for the real fermentation broth (pH: 5.0-6.5 and temperature: 30-80 • C), the resin AMB400 represents an ideal candidate for the extraction of lactic acid during fermentation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Adsorption Behaviour of Lactic Acid on Granular Activated Carbon and Anionic Resins: Thermodynamics, Isotherms and Kinetic Studies

et al. 2017

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“…Recently, we observed that substitution of N 2 with CO 2 in the headspace of a standard culture of Thermotoga neapolitana induced a shift of glucose fermentation towards lactic acid and alanine. [6] For still unknown reasons, the process occurs to the detriment of acetic acid, but does not affect H 2 synthesis. [6] This unexpected result opens up the possibility of the simultaneous production of H 2 and lactic acid, in contrast to the widely accepted model of dark fermentation, which predicts that the conversion of glucose into lactic acid leaves no remaining electrons for H 2 synthesis by hydrogenase.…”

Section: Introductionmentioning

confidence: 99%

“…[6] For still unknown reasons, the process occurs to the detriment of acetic acid, but does not affect H 2 synthesis. [6] This unexpected result opens up the possibility of the simultaneous production of H 2 and lactic acid, in contrast to the widely accepted model of dark fermentation, which predicts that the conversion of glucose into lactic acid leaves no remaining electrons for H 2 synthesis by hydrogenase. [7] Herein, we focus on a biosynthetic process leading to the synthesis of lactic acid in a CO 2 atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Recycling of Carbon Dioxide and Acetate as Lactic Acid by the Hydrogen‐Producing Bacterium Thermotoga neapolitana

2014

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The heterotrophic bacterium Thermotoga neapolitana produces hydrogen by fermentation of sugars. Under capnophilic (carbon dioxide requiring) conditions, the process is preferentially associated with the production of lactic acid, which, as shown herein, is synthesized by reductive carboxylation of acetyl coenzyme A. The enzymatic coupling is dependent on the carbon dioxide stimulated activity of heterotetrameric pyruvate:ferredoxin oxidoreductase. Under the same culture conditions, T. neapolitana also operates the unfavorable synthesis of lactic acid from an exogenous acetate supply. This process, which requires carbon dioxide (or carbonate) and an unknown electron donor, allows for the conversion of carbon dioxide into added-value chemicals without biomass deconstruction.

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“…Recently, it was concluded that to maximize net energy gain via dark fermentation, appropriate cultures capable of high-H 2 yield have to be employed and the process has to be operated at near-ambient temperatures with the lowest feedstock concentration as possible [10]. In an experiment with Thermotoga neapolitana sparged with N 2 and supplemented with 40 mM sodium bicarbonate a 2.8 and 2.7 mol/mol glucose yield of hydrogen with a lactic acid/acetic acid ratio of 0.26 was obtained, challenging the currently accepted dark fermentation model that predicts reduction of this gas when glucose is converted into organic products different from acetate [46]. Pradhan et al reviewed the hydrogen production efficiency of a similar bacterium (Thermotoga neapolitana) with different feedstocks and found 1.9-3.5 mol H 2 /mol hexose yields achievable with a range of feedstocks and variable substrate loads [47].…”

Section: Dark/anaerobic Fermentationmentioning

confidence: 94%

Biohydrogen Production from Lignocellulosic Biomass: Technology and Sustainability

et al. 2015

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Among the various renewable energy sources, biohydrogen is gaining a lot of traction as it has very high efficiency of conversion to usable power with less pollutant generation. The various technologies available for the production of biohydrogen from lignocellulosic biomass such as direct biophotolysis, indirect biophotolysis, photo, and dark fermentations have some drawbacks (e.g., low yield and slower production rate, etc.), which limits their practical application. Among these, metabolic engineering is presently the most promising for the production of biohydrogen as it overcomes most of the limitations in other technologies. Microbial electrolysis is another recent technology that is progressing very rapidly. However, it is the dark fermentation approach, followed by photo fermentation, which seem closer to commercialization. Biohydrogen production from lignocellulosic biomass is particularly suitable for relatively small and decentralized systems and it can be considered as an important sustainable and renewable energy source. The comprehensive life cycle assessment (LCA) of biohydrogen production from lignocellulosic biomass and its comparison with other biofuels can be a tool for policy decisions. In this paper, we discuss the various possible approaches for producing biohydrogen from lignocellulosic biomass which is an globally available abundant resource. The main technological challenges are discussed in detail, followed by potential solutions.

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Capnophilic lactic fermentation and hydrogen synthesis by Thermotoga neapolitana: An unexpected deviation from the dark fermentation model

Cited by 38 publications

References 14 publications

Adsorption Behaviour of Lactic Acid on Granular Activated Carbon and Anionic Resins: Thermodynamics, Isotherms and Kinetic Studies

Adsorption Behaviour of Lactic Acid on Granular Activated Carbon and Anionic Resins: Thermodynamics, Isotherms and Kinetic Studies

Recycling of Carbon Dioxide and Acetate as Lactic Acid by the Hydrogen‐Producing Bacterium Thermotoga neapolitana

Biohydrogen Production from Lignocellulosic Biomass: Technology and Sustainability

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