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Barrena R, Vargas-García MDC, Capell G, Barańska M, Puntes V, Moral-Vico J, Sánchez A, Font X. Sustained effect of zero-valent iron nanoparticles under semi-continuous anaerobic digestion of sewage sludge: Evolution of nanoparticles and microbial community dynamics. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 777:145969. [PMID: 33676214 DOI: 10.1016/j.scitotenv.2021.145969] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 02/12/2021] [Accepted: 02/13/2021] [Indexed: 06/12/2023]
Abstract
The effects of adding zero-valent iron nanoparticles (nZVI) on the physicochemical, biological and biochemical responses of a semi-continuous anaerobic digestion of sewage sludge have been assessed. Two sets of consecutive experiments of 103 and 116 days, respectively, were carried out in triplicate. nZVI were magnetically retained in the reactors, and the effect of punctual doses (from 0.27 to 4.33 g L-1) over time was studied. Among the different parameters monitored, only methane content in the biogas was significantly higher when nZVI was added. However, this effect was progressively lost after the addition, and in 5-7 days, the methane content returned to initial values. The increase in the oxidation state of nanoparticles seems to be related to the loss of effect over time. Higher dose (4.33 g L-1) sustained positive effects for a longer time along with higher methane content, but this fact seems to be related to microbiome acclimation. Changes in microbial community structure could also play a role in the mechanisms involved in methane enhancement. In this sense, the microbial consortium analysis reported a shift in the balance among acetogenic eubacterial communities, and a marked increase in the relative abundance of members assigned to Methanothrix genus, recognized as acetoclastic species showing high affinity for acetate, which explain the rise in methane content in the biogas. This research demonstrates that biogas methane enrichment in semicontinuous anaerobic digesters can be achieved by using nZVI nanoparticles, thus increasing energy production or reducing costs of a later biogas upgrading process.
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Affiliation(s)
- Raquel Barrena
- GICOM research group, Department of Chemical, Biological and Environmental Engineering, Universitat Autònoma de Barcelona, Edifici Q, Carrer de les Sitges, 08193 Bellaterra (Cerdanyola del Vallès), Barcelona, Spain.
| | - María Del Carmen Vargas-García
- Department of Biology and Geology, CITE II-B, Universidad de Almería, Agrifood Campus of International Excellence ceiA3, 04120 Almería, Spain
| | - Georgina Capell
- GICOM research group, Department of Chemical, Biological and Environmental Engineering, Universitat Autònoma de Barcelona, Edifici Q, Carrer de les Sitges, 08193 Bellaterra (Cerdanyola del Vallès), Barcelona, Spain
| | - Maja Barańska
- GICOM research group, Department of Chemical, Biological and Environmental Engineering, Universitat Autònoma de Barcelona, Edifici Q, Carrer de les Sitges, 08193 Bellaterra (Cerdanyola del Vallès), Barcelona, Spain
| | - Victor Puntes
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain; Vall d'Hebron Institut de Recerca (VHIR), 08035 Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), P. Lluís Companys 23, 08010 Barcelona, Spain
| | - Javier Moral-Vico
- GICOM research group, Department of Chemical, Biological and Environmental Engineering, Universitat Autònoma de Barcelona, Edifici Q, Carrer de les Sitges, 08193 Bellaterra (Cerdanyola del Vallès), Barcelona, Spain
| | - Antoni Sánchez
- GICOM research group, Department of Chemical, Biological and Environmental Engineering, Universitat Autònoma de Barcelona, Edifici Q, Carrer de les Sitges, 08193 Bellaterra (Cerdanyola del Vallès), Barcelona, Spain
| | - Xavier Font
- GICOM research group, Department of Chemical, Biological and Environmental Engineering, Universitat Autònoma de Barcelona, Edifici Q, Carrer de les Sitges, 08193 Bellaterra (Cerdanyola del Vallès), Barcelona, Spain
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Lebedev N, Stroud RM, Yates MD, Tender LM. Spatially Resolved Chemical Analysis of Geobacter sulfurreducens Cell Surface. ACS NANO 2019; 13:4834-4842. [PMID: 30943001 DOI: 10.1021/acsnano.9b02032] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Geobacter sulfurreducens is of interest for the highest efficiency of power generation and extremely long extracellular electron transfer (EET) between the bacterium and electrodes. Despite more than 15 years of intensive molecular biological research, there is still no clear answer which molecules are responsible for these processes. In the present work, we look at the problem from another (atomic) perspective and identify the location and shape of the compounds that are known to be conductive, particularly those containing Fe atoms. By using highly sophisticated energy dispersive X-ray spectroscopy combined with high-angle annular dark-field transmission electron microscopy enabling detection, identification, and localization of chemical compounds on the surface at nearly atomic spatial resolution, we analyze Fe spatial distribution within the G. sulfurreducens community. We discover the presence of small Fe-containing particles on the surface of the bacterium cells. The size of the particles (diameter 5.6 nm) is highly reproducible and comparable with the size of a single protein. The particles cover about 2% of the cell surface, which is similar to that expected for molecular conductors responsible for electron transfer through the bacterium cell wall. We find that G. sulfurreducens filaments ("bacterial molecular wires") also contain Fe atoms in their bundles. We observe that the bacterium enable changing the distance between the Fe-containing bundles in the filaments from separated to attached (the latter is needed for the efficient electron transfer between the Fe-containing particles), depending on the bacterium metabolic activity and attachment to extracellular substrates. These results are consistent with the recently published research about the role of Fe atoms in protein molecular conductance ( Phys. Chem. Chem. Phys. , 2018 , 20 , 14072 - 14081 ) and show what type of Fe-containing particles are involved in the bacterial extracellular communication. They can be used for the design and construction of artificial biomolecular wires and bioinorganic interfaces.
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Affiliation(s)
- Nikolai Lebedev
- Center for Bio/Molecular Science and Engineering , U.S. Naval Research Laboratory , Washington , DC 20375 , United States
| | - Rhonda M Stroud
- Materials Science and Technology Division , U.S. Naval Research Laboratory , Washington , DC 20375 , United States
| | - Matthew D Yates
- Center for Bio/Molecular Science and Engineering , U.S. Naval Research Laboratory , Washington , DC 20375 , United States
| | - Leonard Martin Tender
- Center for Bio/Molecular Science and Engineering , U.S. Naval Research Laboratory , Washington , DC 20375 , United States
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He Z, Zhang Q, Feng Y, Luo H, Pan X, Gadd GM. Microbiological and environmental significance of metal-dependent anaerobic oxidation of methane. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 610-611:759-768. [PMID: 28830047 DOI: 10.1016/j.scitotenv.2017.08.140] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 07/22/2017] [Accepted: 08/14/2017] [Indexed: 06/07/2023]
Abstract
Anaerobic oxidation of methane (AOM) can be coupled to the reduction of sulfate, nitrate and nitrite, which effectively reduces methane emission into the atmosphere. Recently, metal-dependent AOM (metal-AOM, AOM coupled to metal reduction) was demonstrated to occur in both environmental samples and enrichment cultures. Anaerobic methanotrophs are capable of respiration using Fe(III) or Mn(IV), whether they are in the form of soluble metal species or insoluble minerals. Given the wide distribution of Fe(III)/Mn(IV)-bearing minerals in aquatic methane-rich environments, metal-AOM is considered to be globally important, although it has generally been overlooked in previous studies. In this article, we discuss the discovery of this process, the microorganisms and mechanisms involved, environmental significance and factors influencing metal-AOM. Since metal-AOM is poorly studied to date, some discussion is included on the present understanding of sulfate- and nitrate-AOM and traditional metal reduction processes using organic substrates or hydrogen as electron donors. Metal-AOM is a relatively new research field, and therefore more studies are needed to fully characterize the process. This review summarizes current studies and discusses the many unanswered questions, which should be useful for future research in this field.
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Affiliation(s)
- Zhanfei He
- College of Environment, Zhejiang University of Technology, Hangzhou, China; Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, Zhejiang University of Technology, Hangzhou, China
| | - Qingying Zhang
- College of Environment, Zhejiang University of Technology, Hangzhou, China
| | - Yudong Feng
- College of Environment, Zhejiang University of Technology, Hangzhou, China
| | - Hongwei Luo
- College of Environment, Zhejiang University of Technology, Hangzhou, China; Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, Zhejiang University of Technology, Hangzhou, China
| | - Xiangliang Pan
- College of Environment, Zhejiang University of Technology, Hangzhou, China; Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, Zhejiang University of Technology, Hangzhou, China.
| | - Geoffrey Michael Gadd
- Geomicrobiology Group, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK
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