Effect of culture conditions on hydrogen production by Thermoanaerobacter strain AK68

Vipotnik, Ziva; Jessen, Jan Eric; Scully, Sean Michael; Örlygsson, Jóhann

doi:10.1016/j.ijhydene.2015.10.124

Cited by 18 publications

(4 citation statements)

References 28 publications

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“…Like other thermophilic anaerobes, Thermoanaerobacter strain AK152 is sensitive to elevated initial substrate concentrations with a decrease in substrate utilization being profound above 30 mM of glucose ( Figure 3 A). Unlike Thermoanaerobacter strain AK68 [ 37 ], AK152 is not particularly sensitive to changes in L-G ratio, in that glucose utilization did not drop or end product formation shift. That said, ethanol yields did increase slightly with increasing L-G ratios with a corresponding decrease in acetate and hydrogen production which suggests that the partial pressure of hydrogen may play a minor role in directing end product profiles ( Figure 3 B).…”

Section: Discussionmentioning

confidence: 99%

Biotransformation of Carboxylic Acids to Alcohols: Characterization of Thermoanaerobacter Strain AK152 and 1-Propanol Production via Propionate Reduction

Scully

Örlygsson

2020

Microorganisms

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Thermoanaerobacter strains have recently gained interest because of their ability to convert short chain fatty acids to alcohols using actively growing cells. Thermoanaerobacter thermohydrosulfuricus strain AK152 was physiologically investigated for its ethanol and other alcohol formation. The temperature and pH optimum of the strain was 70 °C and pH 7.0 and the strain degraded a variety of compounds present in lignocellulosic biomass like monosaccharides, disaccharides, and starch. The strain is highly ethanologenic, producing up to 86% of the theoretical ethanol yield form hexoses. Strain AK152 was inhibited by relatively low initial substrate (30 mM) concentration, leading to inefficient degradation of glucose and levelling up of all end-product formation. The present study shows that the strain produces alcohols from most of the tested carboxylic acids, with the highest yields for propionate conversion to propanol (40.7%) with kinetic studies demonstrating that the maximum conversion happens within the first 48 h of fermentation. Various physiological tests were performed to maximize the acid conversion to the alcohol which reveals that the optimum pH for propionate conversion is pH 6.7 which affords a 57.3% conversion. Kinetic studies reveal that propionate conversion is rapid, achieving a maximum conversion within the first 48 h of fermentation. Finally, by using 13C NMR, it was shown that the addition of propionate indeed converted to propanol.

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Section: Discussionmentioning

confidence: 99%

Biotransformation of Carboxylic Acids to Alcohols: Characterization of Thermoanaerobacter Strain AK152 and 1-Propanol Production via Propionate Reduction

Scully

Örlygsson

2020

Microorganisms

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“…The consumption of glucose and pyruvate by Thermoanaerobium brockii was enhanced as well by using acetone as electron acceptor (Ben‐Bassat et al , ). Also, Vipotnik et al () showed inhibition of glucose consumption by Thermoanaerobacter strain AK68 when exposed to high hydrogen partial pressure and that the addition of thiosulphate or co‐cultivation with Methanothermobacter strain M39 (as electron scavenger) increased the utilization of glucose and acetate production (Vipotnik et al , ). In summary, we show that the presence of a hydrogenotrophic methanogenic partner, acting as biological electron acceptor, enhances glycerol conversion by Thermoanaerobacter species, since it facilitates the redox balance and contributes to a higher energy gain by these bacteria.…”

Section: Discussionmentioning

confidence: 99%

Co‐cultivation of Thermoanaerobacter strains with a methanogenic partner enhances glycerol conversion

Magalhães

Ribeiro

Guedes

et al. 2020

Microbial Biotechnology

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Glycerol-rich waste streams produced by the biodiesel, bioethanol and oleochemical industries can be treated and valorized by anaerobic microbial communities to produce methane. As current knowledge of the microorganisms involved in thermophilic glycerol conversion to methane is scarce, thermophilic glycerol-degrading methanogenic communities were enriched. A co-culture of Thermoanaerobacter and Methanothermobacter species was obtained, pointing to a non-obligately syntrophic glycerol degradation. This hypothesis was further studied by incubating Thermoanaerobacter brockii subsp. finnii and T. wiegelii with glycerol (10 mM) in pure culture and with different hydrogenotrophic methanogens. The presence of the methanogen accelerated glycerol fermentation by the two Thermoanaerobacter strains up to 3.3 mM day À1 , corresponding to 12 times higher volumetric glycerol depletion rates in the methanogenic co-cultures than in the pure bacterial cultures. The catabolic pathways of glycerol conversion were identified by genome analysis of the two Thermoanaerobacter strains. NADH and reduced ferredoxin formed in the pathway are linked to proton reduction, which becomes thermodynamically favourable when the hydrogen partial pressure is kept low by the hydrogenotrophic methanogenic partner.

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“…With the highest glucose initial concentration applied (400 mM), less than 5% of the glucose was degraded. This is well known; other thermophilic anaerobic bacteria are very sensitive towards relatively low initial sugar concentrations, often being inhibited at concentrations above 20-30 mM [6,17].…”

Section: Effect Of Culture Conditions On End-product Formationmentioning

confidence: 94%

“…The pre-treatment of Whatman paper, Rhubarb leaf, and Timothy grass was as described earlier [17]. Briefly, the biomass received Cellulase (1 mL, 700 U/mL, Sigma) via aseptic addition and was incubated at 47 • C for 96 h. The hydrolysates were centrifuged (20 min, 4700 rpm) the resultant supernatant collected, its pH adjusted to 7 with 6 M NaOH, and final volume adjusted to 1 L. The hydrolysates were sequentially vacuum filtered through a 53 µm nylon filter, Whatman #1 filter paper (11 µm), 5 µm nylon filter, and a 0.45 µm filter.…”

Section: Collection Of Rhubarb Biomass and Preparation Of Hydrolysatesmentioning

confidence: 99%

Influence of Inhibitory Compounds on Biofuel Production from Oxalate-Rich Rhubarb Leaf Hydrolysates Using Thermoanaerobacter thermohydrosulfuricus Strain AK91

Örlygsson

Scully

2021

Fuels

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The present investigation is on bioethanol and biohydrogen production from oxalate-rich rhubarb leaves which are an underutilized residue of rhubarb cultivation. Rhubarb leaves can be the feedstock for bioethanol and biohydrogen production using thermophilic, anaerobic bacteria. The fermentation of second-generation biomass to biofuels by Thermoanaerobacter has already been reported as well as their high ethanol and hydrogen yields although rhubarb biomass has not been examined for this purpose. Thermoanaerobacter thermohydrosulfuricus strain AK91 was characterized (temperature and pH optima, substrate utilization spectrum) which demonstrates that the strain can utilize most carbohydrates found in lignocellulosic biomass. Additionally, the influence of specific culture conditions, namely the partial pressure of hydrogen and initial glucose concentration, were investigated in batch culture and reveals that the strain is inhibited. Additionally, batch experiments containing common inhibitory compounds, namely carboxylic acids and aldehydes, some of which are present in high concentrations in rhubarb. Strain AK91 is not affected by alkanoic carboxylic acids and oxalate up to at least 100 mM although the strain was inhibited by 40 mM of malate. Interestingly, strain AK91 demonstrated the ability to reduce alkanoic carboxylic acids to their primary alcohols; more detailed studies with propionate as a model compound demonstrated that AK91’s growth is not severally impacted by high propionate loadings although 1-propanol titers did not exceed 8.5 mM. Additionally, ethanol and hydrogen production from grass and rhubarb leaf hydrolysates was investigated in batch culture for which AK91 produced 7.0 and 6.3 mM g−1, respectively.

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Effect of culture conditions on hydrogen production by Thermoanaerobacter strain AK68

Cited by 18 publications

References 28 publications

Biotransformation of Carboxylic Acids to Alcohols: Characterization of Thermoanaerobacter Strain AK152 and 1-Propanol Production via Propionate Reduction

Biotransformation of Carboxylic Acids to Alcohols: Characterization of Thermoanaerobacter Strain AK152 and 1-Propanol Production via Propionate Reduction

Co‐cultivation of Thermoanaerobacter strains with a methanogenic partner enhances glycerol conversion

Influence of Inhibitory Compounds on Biofuel Production from Oxalate-Rich Rhubarb Leaf Hydrolysates Using Thermoanaerobacter thermohydrosulfuricus Strain AK91

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