Protocols for Calculating Reaction Kinetics and Thermodynamics

Dolfing, Jan

doi:10.1007/8623_2015_109

Cited by 13 publications

(10 citation statements)

References 42 publications

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“…32 All calculation procedures are described in detail by Dolfing. 34 Kinetic Parameters. The generation time was calculated from the qPCR results using the logarithmic growth equation N t = N 0 × e μt , where N t is the number of cells at time t, N 0 is the number of cells at time zero, and μ is the growth rate constant.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

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Growth Characteristics and Thermodynamics of Syntrophic Acetate Oxidizers

Westerholm

Dolfing

Schnürer

2019

Environ. Sci. Technol.

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Syntrophic acetate oxidation (SAO) plays a pivotal role in biogas production processes when aceticlastic methanogens are inhibited. Despite the importance of SAO, the metabolic interactions and syntrophic growth of the organisms involved are still poorly understood. Therefore, we studied growth parameters and interactions within constructed defined cocultures comprising the methanogen Methanoculleus bourgensis and one, or several, of the syntrophic acetate oxidizers Syntrophaceticus schinkii, [Clostridium] ultunense, and Tepidanaerobacter acetatoxydans and a novel, uncharacterized bacterium. Cultivation experiments in a design-of-experiment approach revealed positive effects on methane production rate of increased ammonium levels (up to 0.2 M), temperature (up to 45 °C), and acetate concentrations (0.15−0.30 M). Molecular analyses and thermodynamic calculations demonstrated close interlinkages between the microorganisms, with available energies of −10 kJ/mol for acetate oxidation and −20 kJ/mol for hydrogenotrophic methanogenesis. The estimated generation time varied between 3 and 20 days for all syntrophic microorganisms involved, and the acetate minimum threshold level was 0.40−0.45 mM. The rate of methanogenesis depended on the SAO bacteria present in the culture. These data are beneficial for interpretation of SAO prevalence and competiveness against aceticlastic methanogens in anaerobic environments.

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Section: ■ Materials and Methodsmentioning

confidence: 99%

“…Gibbs free energy (Δ G ) values pertaining to actual concentrations and partial pressures were calculated using the Nernst equation, as described previously . All calculation procedures are described in detail by Dolfing …”

Section: Methodsmentioning

confidence: 99%

Growth Characteristics and Thermodynamics of Syntrophic Acetate Oxidizers

Westerholm

Dolfing

Schnürer

2019

Environ. Sci. Technol.

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“…The pH, temperature, and partial pressure were set as 7.0, 25 °C, and 1 atm, respectively, given their minor difference among the general environments considered and the resulting minor impact on thermodynamic calculation results. Calculations and corrections for each reaction were performed based on the previously reported protocols . The thermodynamics of the overall reaction could be calculated by eliminating the intermediate formate.…”

Section: Methodsmentioning

confidence: 99%

Coupled Aerobic Methane Oxidation and Arsenate Reduction Contributes to Soil-Arsenic Mobilization in Agricultural Fields

Shi

Zhou

Tang

et al. 2022

Environ. Sci. Technol.

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Microbial oxidation of organic compounds can promote arsenic release by reducing soil-associated arsenate to the more mobile form arsenite. While anaerobic oxidation of methane has been demonstrated to reduce arsenate, it remains elusive whether and to what extent aerobic methane oxidation (aeMO) can contribute to reductive arsenic mobilization. To fill this knowledge gap, we performed incubations of both microbial laboratory cultures and soil samples from arsenic-contaminated agricultural fields in China. Incubations with laboratory cultures showed that aeMO could couple to arsenate reduction, wherein the former bioprocess was carried out by aerobic methanotrophs and the latter by a non-methanotrophic bacterium belonging to a novel and uncultivated representative of Burkholderiaceae. Metagenomic analyses combined with metabolite measurements suggested that formate served as the interspecies electron carrier linking aeMO to arsenate reduction. Such coupled bioprocesses also take place in the real world, supported by a similar stoichiometry and gene activity in the incubations with natural paddy soils, and contribute up to 76.2% of soil-arsenic mobilization into pore waters in the top layer of the soils where oxygen was present. Overall, this study reveals a previously overlooked yet significant contribution of aeMO to reductive arsenic mobilization.

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“…Gibbs free energies (ΔG°) of the conversion of propionate to acetate were calculated at 55°C in pH 7.0. The values were computed in accordance with (Alberty 1998; Dolfing 2015).…”

Section: Methodsmentioning

confidence: 99%

Operational and biochemical aspects of co-digestion (co-AD) from sugarcane vinasse, filter cake and deacetylation liquor

Volpi

Júnior

Franco

et al. 2021

Preprint

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This work performed co-AD from the vinasse and filter cake (from 1G ethanol production) and deacetylation liquor (from the pre-treatment of sugarcane straw for 2G ethanol production) in a semi-Continuous Stirred Tank Reactor (s-CSTR) aiming to provide optimum operational parameters for continuous CH4 production. Using filter cake as co-substrate may allow the reactor to operate throughout the year, as it is available in the sugarcane off-season, unlike vinasse. A comparison was made from the microbial community of the seed sludge and the reactor sludge when CH4 production stabilized. Lactate, butyrate and propionate fermentation routes were denoted at the start-up of the s-CSTR, characterizing the acidogenic phase: the Oxidation-Reduction Potential (ORP) values ranged from -800 to -100 mV. Once the methanogenesis was initiated, alkalizing addition was no longer needed as its demand by the microrganisms was supplied by the alkali-characteriscs of the deacetylation liquor. The gradual increase of the applied Organic Load Rates (OLR) allowed stabilization of the methanogenesis from 3.20 gVS L-1 day-1: the highest CH4 yield (230 NmLCH4 gSV-1) and average organic matter removal efficiency (83% + 13) was achieved at ORL of 4.16 gVS L-1day-1. The microbial community changed along the reactor operation, presenting different metabolic routes mainly due to the used lignocellulosic substrates. Bacteria from the syntrophic acetate oxidation (SAO) process coupled to hydrogenotrophic methanogenesis were predominant (~ 2% Methanoculleus) during the CH4 production stability. The overall results are useful as preliminary drivers in terms of visualizing the co-AD process in a sugarcane biorefinery integrated to scale.

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Protocols for Calculating Reaction Kinetics and Thermodynamics

Cited by 13 publications

References 42 publications

Growth Characteristics and Thermodynamics of Syntrophic Acetate Oxidizers

Growth Characteristics and Thermodynamics of Syntrophic Acetate Oxidizers

Coupled Aerobic Methane Oxidation and Arsenate Reduction Contributes to Soil-Arsenic Mobilization in Agricultural Fields

Operational and biochemical aspects of co-digestion (co-AD) from sugarcane vinasse, filter cake and deacetylation liquor

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