Potential enhancement of direct interspecies electron transfer for syntrophic metabolism of propionate and butyrate with biochar in up-flow anaerobic sludge blanket reactors

Zhao, Zhiqiang; Zhang, Yaobin; Holmes, Dawn E.; Dang, Yan; Woodard, Trevor L.; Nevin, Kelly P.; Lovley, Derek R.

doi:10.1016/j.biortech.2016.03.005

Cited by 252 publications

(83 citation statements)

References 32 publications

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“…Interestingly, it appears that conductive materials, including graphite particles (Kato et al ., ; Zhao et al ., ), granular activated carbon (Liu et al ., ; Rotaru et al ., ; Xu et al ., ; Dang et al ., ; Lee et al ., ), biochar (Chen et al ., ; Zhao et al ., ), graphene (Tian et al ., ), carbon nanotubes (CNT) (Li et al ., ; Zhang and Lu, ), carbon felt (Xu et al ., ) and carbon cloth (Chen et al ., ; Zhao et al ., ; Lei et al ., ), but also iron oxides as magnetite (Kato et al ., ; Cruz Viggi et al ., ; Baek et al ., ; Zhuang et al ., ; Yamada et al ., ; Tang et al ., ; Yang et al ., ; Yin et al ., ; Zhang and Lu, ; Jing et al ., ) may increase the rate of electron transfer and may affect metabolic pathways in anaerobic microbial processes by promoting DIET, between bacteria and methanogens. In general, these materials are highly stable, have large surface area, good adsorption capacity and high electric conductivity (Figueiredo et al ., ; Van der Zee and Cervantes, ; Pereira et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Carbon nanotubes accelerate methane production in pure cultures of methanogens and in a syntrophic coculture

Salvador

Martins

Melle‐Franco

et al. 2017

Environmental Microbiology

129

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Carbon materials have been reported to facilitate direct interspecies electron transfer (DIET) between bacteria and methanogens improving methane production in anaerobic processes. In this work, the effect of increasing concentrations of carbon nanotubes (CNT) on the activity of pure cultures of methanogens and on typical fatty acid-degrading syntrophic methanogenic coculture was evaluated. CNT affected methane production by methanogenic cultures, although acceleration was higher for hydrogenotrophic methanogens than for acetoclastic methanogens or syntrophic coculture. Interestingly, the initial methane production rate (IMPR) by Methanobacterium formicicum cultures increased 17 times with 5 g·L CNT. Butyrate conversion to methane by Syntrophomonas wolfei and Methanospirillum hungatei was enhanced (∼1.5 times) in the presence of CNT (5 g·L ), but indications of DIET were not obtained. Increasing CNT concentrations resulted in more negative redox potentials in the anaerobic microcosms. Remarkably, without a reducing agent but in the presence of CNT, the IMPR was higher than in incubations with reducing agent. No growth was observed without reducing agent and without CNT. This finding is important to re-frame discussions and re-interpret data on the role of conductive materials as mediators of DIET in anaerobic communities. It also opens new challenges to improve methane production in engineered methanogenic processes.

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Section: Introductionmentioning

confidence: 99%

Carbon nanotubes accelerate methane production in pure cultures of methanogens and in a syntrophic coculture

Salvador

Martins

Melle‐Franco

et al. 2017

Environmental Microbiology

129

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“…Differences in relative abundance of families between control setups and biochar amendments could explain the shift of the microbial community compositions in both the ferrihydrite enrichments ( Figure 4 ). This was expected since biochar has also been demonstrated to enrich iron(III)-reducing bacteria in sludge, wastewater, and soils (Tong et al, 2014; Zhao et al, 2016). The Geobacteraceae family is well known for the ability to utilize acetate as an electron donor for the reduction of Fe(III) (Röling, 2014).…”

Section: Discussionmentioning

confidence: 97%

“…The high iron(III) containing culture environments led to a high relative abundance of iron(III)-reducing bacteria, which was likely outcompete the methanogens for the acetate ( Figures 1 – 4 ). The increase in the relative abundance of iron(III)-reducing bacteria and methanogens ( Figures 1 – 4 ) by natural humic acid and application of biochar, especially the small particle size of biochar, may enhance the interaction between these two kinds of microbes (Tong et al, 2014; Zhao et al, 2016). Additionally, cooperation is necessary between the iron(III)-reducing microorganisms and methanogens.…”

Section: Discussionmentioning

confidence: 99%

Biochar Addition Increases the Rates of Dissimilatory Iron Reduction and Methanogenesis in Ferrihydrite Enrichments

et al. 2017

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Biochar contains quinones and aromatic structures that facilitate extracellular electron transfer between microbial cells and insoluble minerals. In this study, granulated biochar (1.2–2 mm) and powdered biochar (<0.15 mm) were amended to two ferrihydrite (in situ ferrihydrite and ex situ ferrihydrite) enrichments to investigate the effect of biochar with different particle sizes on dissimilatory iron(III)-reducing bacteria (DIRB) and methanogens. Biochar addition significantly stimulated the reduction of both in situ ferrihydrite and ex situ ferrihydrite and the production of methane. Powdered biochar amendments increased iron reduction compared to granulated biochar amendment in both the in situ ferrihydrite and ex situ ferrihydrite enrichments. However, no significant difference was observed in methane production between the powdered biochar and granulated biochar amendments in the two ferrihydrite enrichments. Analysis of 16S rRNA gene sequences showed that both DIRB and methanogens were enriched after biochar amendments in the in situ ferrihydrite and ex situ ferrihydrite enrichments. Taxa belonging to the Geobacteraceae and methanogenic genus affiliated to Methanosarcina were detected with significantly higher relative abundances in powdered biochar amendments than those in granulated biochar amendments in both the ferrihydrite enrichments. X-ray diffraction analysis indicated green rust [Fe2(CO3) (OH)] and vivianite [Fe3(PO4)2 8(H2O)] formed in the ex situ ferrihydrite and in situ ferrihydrite enrichments without biochar addition, respectively. After granulated biochar amendment, the mineral phase changed from the green rust to vivianite in the ex situ ferrihydrite enrichment, while crystalline vivianite and iron oxide (γ-Fe2O3) were detected simultaneously in the in situ ferrihydrite enrichment. No crystalline iron compound was found in the powdered biochar amendments in both ferrihydrite enrichments. Overall, our study illustrated that the addition of biochar affected iron-reducing and methane-generating microbial communities to some extent.

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“…This result supported the fact that the major reason for the improved performance was the conductivity of the material and not the biomass retention. Zhao et al [66] reported the enhancement in methane production (16-25% increase compared to the control) from propionate and butyrate in the UASB with biochar amendment. A significant enrichment of Geobacter and Methanosaeta species compared to the control reactor suggested that the degradation of the organic acid was promoted by the biochar-mediated DIET.…”

Section: Biochar and Activated Carbonmentioning

confidence: 99%

Role and Potential of Direct Interspecies Electron Transfer in Anaerobic Digestion

et al. 2018

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Anaerobic digestion (AD) is an effective biological treatment for stabilizing organic compounds in waste/wastewater and in simultaneously producing biogas. However, it is often limited by the slow reaction rates of different microorganisms' syntrophic biological metabolisms. Stable and fast interspecies electron transfer (IET) between volatile fatty acid-oxidizing bacteria and hydrogenotrophic methanogens is crucial for efficient methanogenesis. In this syntrophic interaction, electrons are exchanged via redox mediators such as hydrogen and formate. Recently, direct IET (DIET) has been revealed as an important IET route for AD. Microorganisms undergoing DIET form interspecies electrical connections via membrane-associated cytochromes and conductive pili; thus, redox mediators are not required for electron exchange. This indicates that DIET is more thermodynamically favorable than indirect IET. Recent studies have shown that conductive materials (e.g., iron oxides, activated carbon, biochar, and carbon fibers) can mediate direct electrical connections for DIET. Microorganisms attach to conductive materials' surfaces or vice versa according to particle size, and form conductive biofilms or aggregates. Different conductive materials promote DIET and improve AD performance in digesters treating different feedstocks, potentially suggesting a new approach to enhancing AD performance. This review discusses the role and potential of DIET in methanogenic systems, especially with conductive materials for promoting DIET.

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Potential enhancement of direct interspecies electron transfer for syntrophic metabolism of propionate and butyrate with biochar in up-flow anaerobic sludge blanket reactors

Cited by 252 publications

References 32 publications

Carbon nanotubes accelerate methane production in pure cultures of methanogens and in a syntrophic coculture

Carbon nanotubes accelerate methane production in pure cultures of methanogens and in a syntrophic coculture

Biochar Addition Increases the Rates of Dissimilatory Iron Reduction and Methanogenesis in Ferrihydrite Enrichments

Role and Potential of Direct Interspecies Electron Transfer in Anaerobic Digestion

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