Enhancing sludge methanogenesis with improved redox activity of extracellular polymeric substances by hematite in red mud

Ye, Jie; Hu, Andong; Ren, Guoping; Chen, Man; Tang, Jiahuan; Zhang, Panyue; Zhou, Shungui; He, Zhen

doi:10.1016/j.watres.2018.01.062

Cited by 219 publications

(82 citation statements)

References 65 publications

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“…Actinobacteria, Synergistetes and Chloroflexi as the famous anaerobic hydrolytic and acidifying phyla (Ahlert et al, 2016; Xie et al, 2016), the increase of their relative abundance may accelerate the hydrolysis-acidification process of granular sludge, illustrating that EPS as an additive could enrich functional microorganisms and enhance methane production. This result was similar to that of the effect of conductive materials (granular activated carbon and hematite) on the microbial community structure, both of which can enrich functional microorganisms and change the microbial community structure (Ye et al, 2018; Zhang et al, 2017). Interestingly, the addition of EPS hardly changed the abundance of archaea compared with the control reactor.…”

Section: Resultssupporting

confidence: 83%

“…c-Cyts stored in EPS played an important role in the electron transfer between fermenting bacteria and methanogens (Ye et al, 2018). The absorbance of c-Cyts (419 nm) increased as the anaerobic digestion proceeded in all reactors.…”

Section: Resultsmentioning

confidence: 99%

“…The protein, humus and polysaccharide concentrations were determined by a modified Lowry method and the anthrone-sulfuric acid spectrophotometric method using bovine serum albumin, humic acid salt and glucose as the respective standards. UV/Visible (UV/Vis) spectroscopy in a diffuse transmission mode was used to measure the electronic absorption spectra of the multi-heme c-Cyts in the EPS (Ye et al, 2018). EEM fluorescence spectroscopy was used to characterize EPS in this research, and excitation and emission spectra were scanned from 220 to 550 nm in 5 nm increments and from 250 to 550 nm in 5 nm increments, respectively (Ding et al, 2015).…”

Section: Methodsmentioning

confidence: 99%

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Use of extracellular polymer substances as additives for improving biogas yield and digestion performance

Guo

et al. 2019

Preprint

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To understand how extracellular polymer substances (EPS) as additives promotes methanogenesis, 9 batch tests of methane production potential in anaerobic reactors with the addition of EPS or not were conducted. 10Research showed that EPS increased remarkably methane production during anaerobic digestion 11 (36.5% increase compared with the control). EPS enriched functional microorganisms such as Firmicutes, 12Actinobacteria, Synergistetes, and Chloroflexi. Among them, 8.86% OTUs from the important hydrolysis and 13 acidification phyla, which may be an important reason for the enhanced methanogenic capacity of anaerobic 14 granular sludge. Additionally, EPS also improved the abundance of cytochrome c (c-Cyts), accelerating the 15 direct interspecies electron transfer (DIET) between syntrophic bacteria and methanogens, thus enhancing the 16 methane production. Interestingly, the average particle size, volatile suspended solids/total suspended solids 17 (VSS/TSS) and EPS content of anaerobic granular sludge (AnGS) in the EPS reactor were approximately equal 18 to that of the control reactor during the anaerobic digestion, illustrating that EPS could not affect the 19 physicochemical properties of AnGS. Therefore, these results suggested that EPS mainly played a role in the 20 form of conductive materials in the anaerobic digestion process. Compared with conductive materials, EPS as 21 biomass conductive materials was not only environmentally friendly and economical but also no secondary 22 pollution. 23 materials 25 26 Importance 27Compared with the reported conductive materials, EPS has the potential of biodegradation, electron transfer 28 and no significant secondary pollution. Besides, there are few studies on the utilization of EPS resources, 29 especially the effect of EPS as an additive on anaerobic digestion performance. To clarify whether EPS as 30 conductive materials or carbon source promotes methanogenesis. Therefore, in this study, we investigated the 31 influence of EPS as an additive on the methanogenic capacity, physical-chemical properties, microbial 32 community structure and metabolic function of anaerobic granular sludge (AnGS), and preliminarily expatiate 33 the influence mechanism of EPS as an additive on methanogenesis. At the meantime, the research is expected to 34 provide new solutions for the improvement of anaerobic digestion performance and disposal of waste mud. 35 36 43 1 *Corresponding authors. Tel.: +86 18648908256; fax: +86 18648908256.

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Section: Resultssupporting

confidence: 83%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Use of extracellular polymer substances as additives for improving biogas yield and digestion performance

Guo

et al. 2019

Preprint

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“…Geobacter species are widely distributed in the subsurface and even flourish in these Fe(III)‐reducing sedimentary environments or specific habitats (such as anaerobic wastewater digesters, bioremediation sites of uranium‐contaminated aquifers and iron‐rich rhizospheres) (Lovley et al, ). In addition, they have frequently been enriched and isolated from environmental and wastewater samples worldwide (Martins, Salvador, Pereira, & Alves, ; Miceli, Parameswaran, Kang, Krajmalnik‐Brown, & Torres, ; Ye et al, ).…”

Section: Introductionmentioning

confidence: 99%

Molecular evidence for the adaptive evolution of Geobacter sulfurreducens to perform dissimilatory iron reduction in natural environments

Liu

Yin

Xiao

et al. 2019

Molecular Microbiology

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The electrically conductive pili (e-pili) of Geobacter species enable extracellular electron transfer to insoluble metallic minerals, electrodes and other microbial species, which confers biogeochemical significance and global prevalence on Geobacter in diverse anaerobic environments. E-pili are constructed by truncated PilA which is considered to have evolved from full-length pilin by gene fission under positive evolutionary selection. However, this hypothesis is based on phylogenetic analysis and has not yet been experimentally confirmed. Here, we reconstructed an ancestral strain of G. sulfurreducens (designated COMB) carrying full-length PilA by combining genes GSU1496 and GSU1497. The results demonstrated that strain COMB expressed and assembled the full-length fused PilA and exhibited an outer membrane c-type cytochrome profile similar to the wild-type strain. Surprisingly, the generated COMB-pili were also conductive, indicating the evolution of truncated PilA did not occur for conductivity. Moreover, strain COMB minimally reduced Fe(III) oxides but maintained its ability to respire electrodes, demonstrating the truncation of pilin enables iron respiration. This study provides the first experimental evidence that the truncation of pilin in Geobacter species confers adaption to Fe(III)-mineral-mediated selective pressures, and suggests an evolutionary event during which the separation of the GSU1497 gene helped Geobacter survive and thrive in natural environments. K E Y W O R D S adaptive evolution, dissimilatory iron reduction, e-pili, Geobacter sulfurreducens, truncated pilin S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section. How to cite this article: Liu X, Ye Y, Xiao K, Rensing C, Zhou S. Molecular evidence for the adaptive evolution of Geobacter sulfurreducens to perform dissimilatory iron reduction in natural environments. Mol Microbiol. 2020;113:783-793.

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“…Numerous countries are finding new energies to cope with the extreme consumption of fossil fuels. Anaerobic digestion with methane output as the main energetic component has been studied by many researchers [1][2][3][4][5]. However, the lower energy density and economic value of methane limits its practical application [6].…”

Section: Introductionmentioning

confidence: 99%

Effect of Acid/Ethanol Ratio on Medium Chain Carboxylate Production with Different VFAs as the Electron Acceptor: Insight into Carbon Balance and Microbial Community

et al. 2019

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Medium chain carboxylates (MCCs) are important precursors for biodiesel production. Using chain elongation to produce MCCs is an emerging bioenergy technology. In this study, batch tests were conducted to investigate fermentative MCC production through chain elongation from acetate, propionate, n-butyrate, and ethanol. The effect of the acid/ethanol ratio on MCC production by mixed culture was investigated. Better MCC production, especially n-caproate production, was achieved at optimal acid/ethanol ratios of 1:4, 1:3, and 1:2 with acetate, propionate, and n-butyrate as the electron acceptor, respectively. The n-caproate concentration was high, up to 41.54 mmol/L, and the highest n-caproate production efficiency was 57.96% with the n-butyrate/ethanol ratio of 1:2. The higher concentration of ethanol might stimulate the growth of chain elongation bacteria to promote chain elongation. The highest MCC production efficiency with different electron acceptors corresponded to less carbon loss and a higher chain elongation degree. In addition, with the optimal acid/ethanol ratio, the substrate was maximally utilized for chain elongation. The microbial community analysis confirmed the carbon balance analysis with the maximum relative abundance of 52.66–60.55% of the n-caproate producer Clostridium_sensu_stricto_12 enriched by the optimal acid/ethanol ratios with different volatile fatty acids (VFAs) as electron acceptors.

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Enhancing sludge methanogenesis with improved redox activity of extracellular polymeric substances by hematite in red mud

Cited by 219 publications

References 65 publications

Use of extracellular polymer substances as additives for improving biogas yield and digestion performance

Use of extracellular polymer substances as additives for improving biogas yield and digestion performance

Molecular evidence for the adaptive evolution of Geobacter sulfurreducens to perform dissimilatory iron reduction in natural environments

Effect of Acid/Ethanol Ratio on Medium Chain Carboxylate Production with Different VFAs as the Electron Acceptor: Insight into Carbon Balance and Microbial Community

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