Effect of nano zero-valent iron addition on caproate fermentation in carboxylate chain elongation system

Fu, Xindi; Ye, Rong; Jin, Xi; Lu, Wenjing

doi:10.1016/j.scitotenv.2020.140664

Cited by 38 publications

(11 citation statements)

References 46 publications

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“…At high nZVI concentrations (5 g⋅L –1 ), other potential n-butyrate producers such as Oscillibacter , unclassified Oscillospiraceae and Sedimentibacter species were enriched. These taxa have also been enriched in bioelectrochemical systems ( Breitenstein et al, 2002 ; Lin et al, 2018 ; Dessì et al, 2021 ) and Oscillibacter species in ethanol-based chain elongation with nZVI ( Fu et al, 2020 ; Wang et al, 2020 ). However, nZVI caused higher pH conditions and directed the conversion of residual lactate toward propionate formation.…”

Section: Discussionmentioning

confidence: 99%

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nZVI Impacts Substrate Conversion and Microbiome Composition in Chain Elongation From D- and L-Lactate Substrates

Contreras-Dávila

Esveld

Buisman

et al. 2021

Front. Bioeng. Biotechnol.

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Medium-chain carboxylates (MCC) derived from biomass biorefining are attractive biochemicals to uncouple the production of a wide array of products from the use of non-renewable sources. Biological conversion of biomass-derived lactate during secondary fermentation can be steered to produce a variety of MCC through chain elongation. We explored the effects of zero-valent iron nanoparticles (nZVI) and lactate enantiomers on substrate consumption, product formation and microbiome composition in batch lactate-based chain elongation. In abiotic tests, nZVI supported chemical hydrolysis of lactate oligomers present in concentrated lactic acid. In fermentation experiments, nZVI created favorable conditions for either chain-elongating or propionate-producing microbiomes in a dose-dependent manner. Improved lactate conversion rates and n-caproate production were promoted at 0.5–2 g nZVI⋅L–1 while propionate formation became relevant at ≥ 3.5 g nZVI⋅L–1. Even-chain carboxylates (n-butyrate) were produced when using enantiopure and racemic lactate with lactate conversion rates increased in nZVI presence (1 g⋅L–1). Consumption of hydrogen and carbon dioxide was observed late in the incubations and correlated with acetate formation or substrate conversion to elongated products in the presence of nZVI. Lactate racemization was observed during chain elongation while isomerization to D-lactate was detected during propionate formation. Clostridium luticellarii, Caproiciproducens, and Ruminococcaceae related species were associated with n-valerate and n-caproate production while propionate was likely produced through the acrylate pathway by Clostridium novyi. The enrichment of different potential n-butyrate producers (Clostridium tyrobutyricum, Lachnospiraceae, Oscillibacter, Sedimentibacter) was affected by nZVI presence and concentrations. Possible theories and mechanisms underlying the effects of nZVI on substrate conversion and microbiome composition are discussed. An outlook is provided to integrate (bio)electrochemical systems to recycle (n)ZVI and provide an alternative reducing power agent as durable control method.

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Section: Discussionmentioning

confidence: 99%

“…Thus, appropriate nZVI doses should be added to adequately steer the microbiome. Recent reports on ethanol-elongating microbiomes showed improved substrate conversion to MCC with nZVI supplementation ( Fu et al, 2020 ; Wang et al, 2020 ). However, nZVI effects on lactate-based chain elongation have not been studied.…”

Section: Introductionmentioning

confidence: 99%

nZVI Impacts Substrate Conversion and Microbiome Composition in Chain Elongation From D- and L-Lactate Substrates

Contreras-Dávila

Esveld

Buisman

et al. 2021

Front. Bioeng. Biotechnol.

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“…Although some studies have found that NZVI favors the enrichment of acids-producing bacteria [20,21], NZVI and iron-oxygen compounds might have different effects on microbial communities in the presence of electric elds. For this purpose, seven samples were analyzed for the microbial community.…”

Section: Microbial Quantity and Community Analyses Of Catholyte And B...mentioning

confidence: 97%

“…Notably, nano zero-valent iron (NZVI) acted as a pH buffer, electron donor and activator for chain elongation, has gained remarkable attention in promoting the anaerobic digestion (AD) processes for hydrogen and caproate production [19][20][21]. The main promotion mechanisms of dosing NZVI in the sludge AD process has been well summarized by Fu et al [20,21]: 1) hydrogen produced by NZVI anaerobic corrosion ( Fe + 2H 2 O → Fe 2+ + 2OH -+ H 2 ) can be used as an electron donor for chain elongation; 2) the strong reducibility of NZVI creates selective pressure on microbial community and promotes the abundance of Clostridium sp, one common species of chain-elongating. Although NZVI has been proved to promote the caproate production from waste sludge by providing additional electrons and selective pressure for chain-elongating bacterial [19][20][21], to our knowledge, these mechanisms have not been applied to the carbon dioxide conversion in MES.…”

Section: Introductionmentioning

confidence: 99%

“…The main promotion mechanisms of dosing NZVI in the sludge AD process has been well summarized by Fu et al [20,21]: 1) hydrogen produced by NZVI anaerobic corrosion ( Fe + 2H 2 O → Fe 2+ + 2OH -+ H 2 ) can be used as an electron donor for chain elongation; 2) the strong reducibility of NZVI creates selective pressure on microbial community and promotes the abundance of Clostridium sp, one common species of chain-elongating. Although NZVI has been proved to promote the caproate production from waste sludge by providing additional electrons and selective pressure for chain-elongating bacterial [19][20][21], to our knowledge, these mechanisms have not been applied to the carbon dioxide conversion in MES. In addition, the electron loss caused by overpotential is a common problem in MES, which means that the optimization of applied voltage is the premise of creating an excellent thermodynamic environment for hydrogen-mediated electron transfer [22].…”

Section: Introductionmentioning

confidence: 99%

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Nano zero-valent iron assisted microbial electrosynthesis for medium-chain fatty acids production

Zhang

et al. 2022

Preprint

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Background: Microbial electrosynthesis (MES) has been considered a promising platform for carboxylic acids production using homoacetogenic and chain-elongating bacteria. However, this biotechnology is still in its infancy, and many limitations are needed to be transcended, such as low electron transfer efficiency between cathode and microbes.Results: In this study, nano zero-valent iron (NZVI) was employed to improve carboxylic acid production in the MES system. The final accumulated acetate, butyrate, and caproate concentration enhanced from 700.1, 53.6, and 11.8 mg/L to 1.6, 1.1, and 0.7 g/L, with the maximum yield on bicarbonate of 20.7%, 18.7%, and 13.7%, respectively. Besides performing as an additional electron donor, NZVI was also proven to facilitate the formation of electroactive biofilms according to the results of DNA concentration. In addition, it was found that the anaerobic corrosion of NZVI promoted the domination of hydrogen-producing bacteria Paraclostridium, with the increasing relative abundance from 16.78% to 44.18% in the biofilm under open-circuit mode. While under the closed-circuit, the presence of NZVI resulted in significantly higher relative abundances of homoacetogenic bacteria (Terrisporobacter: 20.91%) and chain-elongating bacteria (Clostridium-sensu-stricto-12: 11.8%) in biofilm than in the catholyte (2.18% and 1.63% correspondingly).Conclusions: This study provided the evidence and revealed how NZVI assisted carboxylic acid production in MES and contributes to the application prospects of MES for carbon utilization and energy sustainability.

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Regulation on C2‐C8 carboxylic acid biosynthesis from anaerobic CO₂ fermentation

Liu

et al. 2022

Engineering in Life Sciences

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Bioconversion of CO2 into liquid fuels or chemicals, preferred medium chain carboxylic acids (caproic and caprylic acid), is an attractive CO2 utilization technology. The present study aims to investigate the effects of different ratios of H2/CO2 on regulating the distribution of C2‐C8 carboxylic acid products, while the headspace pressure of 1.5 bar was set to amplify the effect of different ratios. The H2/CO2 ratio of 4:1 was more suitable for preparing acetic acid, where the highest acetic acid yield was 17.5 g/L. And the H2/CO2 ratio of 2:1 showed excellent chain elongation ability with the highest n‐caprylic yield of 2.4 g/L. Additionally, the actual H2/CO2 ratios of 4:1 reactors were higher than that in 2:1 may be course chain elongation often accompanied by H2 production. The 16S rRNA genes analysis shows that the genus Terrisporobacter and Coriobacteriales may be related to acetic acid production enriched in H2/CO2 ratio 4:1 reactors, and the genus Clostridium and Paenibacillaceae may associate with the chain elongation pathway were enriched in H2/CO2 ratio 2:1 reactors.

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Effect of nano zero-valent iron addition on caproate fermentation in carboxylate chain elongation system

Cited by 38 publications

References 46 publications

nZVI Impacts Substrate Conversion and Microbiome Composition in Chain Elongation From D- and L-Lactate Substrates

nZVI Impacts Substrate Conversion and Microbiome Composition in Chain Elongation From D- and L-Lactate Substrates

Nano zero-valent iron assisted microbial electrosynthesis for medium-chain fatty acids production

Regulation on C2‐C8 carboxylic acid biosynthesis from anaerobic CO₂ fermentation

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Effect of nano zero-valent iron addition on caproate fermentation in carboxylate chain elongation system

Cited by 38 publications

References 46 publications

nZVI Impacts Substrate Conversion and Microbiome Composition in Chain Elongation From D- and L-Lactate Substrates

nZVI Impacts Substrate Conversion and Microbiome Composition in Chain Elongation From D- and L-Lactate Substrates

Nano zero-valent iron assisted microbial electrosynthesis for medium-chain fatty acids production

Regulation on C2‐C8 carboxylic acid biosynthesis from anaerobic CO2 fermentation

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Regulation on C2‐C8 carboxylic acid biosynthesis from anaerobic CO₂ fermentation