Thermodynamic analysis of direct interspecies electron transfer in syntrophic methanogenesis based on the optimized energy distribution

Liu, Yu; Gu, Mengqi; Yin, Qidong; Du, Jin; Wu, Guangxue

doi:10.1016/j.biortech.2019.122345

Cited by 27 publications

(3 citation statements)

References 42 publications

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“…While there is no direct evidence that polymer storage is occurring in these organisms, other undescribed traits that enable resiliency may be present. Additionally, while most studies investigating the minimum required free energy release have found values close to 50 kJ per mol ATP ( 34 ), ATP production may be possible with less free energy release ( 35 ). Lastly, computational methods to predict the abundance of specific guilds, rather than relying on relative abundances as a model input, are needed.…”

Section: Resultsmentioning

confidence: 99%

Diagnosing and Predicting Mixed-Culture Fermentations with Unicellular and Guild-Based Metabolic Models

et al. 2020

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Multispecies microbial communities determine the fate of materials in the environment and can be harnessed to produce beneficial products from renewable resources. In a recent example, fermentations by microbial communities have produced medium-chain fatty acids (MCFAs). Tools to predict, assess, and improve the performance of these communities, however, are limited. To provide such tools, we constructed two metabolic models of MCFA-producing microbial communities based on available genomic, transcriptomic, and metabolomic data. The first model is a unicellular model (iFermCell215), while the second model (iFermGuilds789) separates fermentation activities into functional guilds. Ethanol and lactate are fermentation products known to serve as substrates for MCFA production, while acetate is another common cometabolite during MCFA production. Simulations with iFermCell215 predict that low molar ratios of acetate to ethanol favor MCFA production, whereas the products of lactate and acetate coutilization are less dependent on the acetate-to-lactate ratio. In simulations of an MCFA-producing community fed a complex organic mixture derived from lignocellulose, iFermGuilds789 predicted that lactate was an extracellular cometabolite that served as a substrate for butyrate (C4) production. Extracellular hexanoic (C6) and octanoic (C8) acids were predicted by iFermGuilds789 to be from community members that directly metabolize sugars. Modeling results provide several hypotheses that can improve our understanding of microbial roles in an MCFA-producing microbiome and inform strategies to increase MCFA production. Further, these models represent novel tools for exploring the role of mixed microbial communities in carbon recycling in the environment, as well as in beneficial reuse of organic residues. IMPORTANCE Microbiomes are vital to human health, agriculture, and protecting the environment. Predicting behavior of self-assembled or synthetic microbiomes, however, remains a challenge. In this work, we used unicellular and guild-based metabolic models to investigate production of medium-chain fatty acids by a mixed microbial community that is fed multiple organic substrates. Modeling results provided insights into metabolic pathways of three medium-chain fatty acid-producing guilds and identified potential strategies to increase production of medium-chain fatty acids. This work demonstrates the role of metabolic models in augmenting multi-omic studies to gain greater insights into microbiome behavior.

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Section: Resultsmentioning

confidence: 99%

Diagnosing and Predicting Mixed-Culture Fermentations with Unicellular and Guild-Based Metabolic Models

et al. 2020

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“…For example, interspecies hydrogen transfer is a key interaction that has been observed or suggested for various anoxic environments. This process can reduce the partial pressure of hydrogen in the immediate environment sufficiently for H 2 -producing metabolic reactions such as acetogenesis to become thermodynamically favorable [ 131 ]. Within the subsurface environment context, a simple community consisting of Pseudomonas and a SRB belonging to the family Peptococcaceae was discovered in Opalinus Clay borehole water via metagenomic sequencing [ 78 ].…”

Section: Introductionmentioning

confidence: 99%

Microbial ecology of the deep terrestrial subsurface

Beaver,

Neufeld

2024

The ISME Journal

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The terrestrial subsurface hosts diverse microbial communities that, collectively, are predicted to comprise as many microbial cells as global surface soils. Although initially thought to be associated with deposited organic matter, contemporary research demonstrates that deep subsurface microbial communities are supported by chemolithoautotrophic primary production, with hydrogen serving as an important source of electrons. Despite recent progress, relatively little is known about the deep terrestrial subsurface compared to more commonly studied environments. Understanding the composition of deep terrestrial subsurface microbial communities and the factors that influence them is of importance because of human-associated activities including long-term storage of used nuclear fuel, carbon capture, and storage of hydrogen for use as an energy vector. In addition to identifying deep subsurface microorganisms, recent research focuses on identifying the roles of microorganisms in subsurface communities, as well as elucidating myriad interactions – syntrophic, episymbiotic, and viral – that occur among community members. In recent years, entirely new groups of microorganisms (i.e., CPR bacteria and DPANN archaea) have been discovered in deep terrestrial subsurface environments, suggesting that much remains unknown about this biosphere. This review explores the historical context for deep terrestrial subsurface microbial ecology and highlights recent discoveries that shape current ecological understanding of this poorly explored microbial habitat. Additionally, we highlight the need for multifaceted experimental approaches to observe phenomena such as cryptic cycles, complex interactions, and episymbiosis, which may not be apparent when using single approaches in isolation, but are nonetheless critical to advancing our understanding of this deep biosphere.

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“…Methanogens accept electrons and methane can be generated via the reduction of CO 2 . Many models of extracellular electron transfer have been reported in previous studies, including the utilization of cytochrome C or pili (fibrous protein polymer of microorganism cells) in an electron shuttle-mediated model where DIET is promoted between bacteria and methanogens . Conductive materials, such as carbon cloth, biochar, graphite, and magnetite, can act like pili and serve as electrical connections to facilitate mutual metabolism. − The addition of GAC to an AD system containing MS can enhance the DIET process and increase methane production .…”

Section: Introductionmentioning

confidence: 99%

Enhancing the Performance and Stability of the Co-anaerobic Digestion of Municipal Sludge and Food Waste by Granular Activated Carbon Dosing

et al. 2020

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This study investigated the effects of granular activated carbon (GAC) dosing on the co-anaerobic digestion of municipal sludge and food waste. It was found that methane production increased in the GAC systems. The cumulative methane production in the 1 g·L–1 GAC system was 12.14% higher than the control. The 1 g·L–1 GAC system started very quickly at the initial stage of anaerobic digestion (AD) and reached the highest methane production per day on the 3rd day, while the control appeared on the 10th day. The maximum methane production per day of the 1 g·L–1 experimental group was 12.27% higher than that of the control. The pH of the 1 g·L–1 experimental group varied less during the entire AD cycle. The reduction in sCOD, TS, and VS of the 1 g·L–1 GAC system were 48.95, 23.26, and 10.20% higher than the control, respectively. The dominant bacteria in the GAC systems were Thermotogae, Firmicutes, and Bacteroidetes, and these bacteria play very important roles in the hydrolysis and acidification stages. The main methanogen genus in the control was Methanosarcina, and those in the experimental systems were Methanobacterium and Methanolinea (which are hydrogenotrophic methanogenic archaea). These results indicate that the addition of GAC can relieve the acidification, reduce the AD start-up time, and promote the activities and growth of microorganisms to improve methane production by enhancing direct interspecific electron transfer and interspecies hydrogen transfer.

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Thermodynamic analysis of direct interspecies electron transfer in syntrophic methanogenesis based on the optimized energy distribution

Cited by 27 publications

References 42 publications

Diagnosing and Predicting Mixed-Culture Fermentations with Unicellular and Guild-Based Metabolic Models

Diagnosing and Predicting Mixed-Culture Fermentations with Unicellular and Guild-Based Metabolic Models

Microbial ecology of the deep terrestrial subsurface

Enhancing the Performance and Stability of the Co-anaerobic Digestion of Municipal Sludge and Food Waste by Granular Activated Carbon Dosing

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