Amelia-Elena Rotaru

Amelia-Elena Rotaru
University of Southern Denmark | SDU · Department of Biology

Dr. Rer. Nat. (Doctorate in Natural Sciences)

About

59
Publications
28,823
Reads
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5,928
Citations
Introduction
Associate professor/Group Leader at the University of Southern Denmark. My team is working on electromicrobiology and microbial interspecies interactions. Our aim is to provide fundamental knowledge about methanogenic archaea to develop sustainable microbial biotech applications and to inform climate models of new possible sources of greenhouse gas emissions.
Additional affiliations
November 2018 - present
University of Southern Denmark
Position
  • Professor (Associate)
February 2017 - July 2017
University of Massachusetts Amherst
Position
  • Professor
November 2015 - October 2018
University of Southern Denmark
Position
  • Professor (Assistant)
Education
April 2005 - June 2009
October 2003 - April 2005
Max Planck Institute for Marine Microbiology
Field of study
  • Marine Microbiology

Publications

Publications (59)
Article
Full-text available
Anaerobic conversion of organic wastes and biomass to methane is an important bioenergy strategy, which depends on poorly understood mechanisms of interspecies electron transfer to methanogenic microorganisms. Metatranscriptomic analysis of methanogenic aggregates from a brewery wastewater digester, coupled with fluorescence in situ hybridization w...
Article
Full-text available
Coastal sediments are rich in conductive particles, possibly affecting microbial processes for which acetate is a central intermediate. In the methanogenic zone, acetate is consumed by methanogens and/or syntrophic acetate-oxidizing (SAO) consortia. SAO consortia live under extreme thermodynamic pressure, and their survival depends on successful pa...
Article
Full-text available
Microbially induced corrosion of metallic iron (Fe0)-containing structures is an environmental and economic hazard. Methanogens are abundant in low-sulfide environments and yet their specific role in Fe0 corrosion is poorly understood. In this study, Sporomusa and Methanosarcina dominated enrichments from Baltic Sea methanogenic sediments that were...
Article
Full-text available
The co-occurrence of Geobacter and Methanosarcinales is often used as a proxy for the manifestation of direct interspecies electron transfer (DIET) in the environment. Here we tested eleven new co-culture combinations between methanogens and electrogens. Previously, only the most electrogenic Geobacter paired by DIET with Methanosarcinales methanog...
Article
Full-text available
Diverse physiological groups congregate into environmental corrosive biofilms, yet the interspecies interactions between these corrosive physiological groups are seldom examined. We, therefore, explored Fe0-dependent cross-group interactions between acetogens and methanogens from lake sediments. On Fe0, acetogens were more corrosive and metabolical...
Preprint
Electromethanogenesis is the electrochemical conversion of carbon dioxide (CO 2 ) to methane (CH 4 ) with microorganisms as catalysts, and it is a promising approach for biogas upgrading. Many studies have shown increased methane production by electrochemical stimulation, allegedly due to the enhancement of direct interspecies electron transfer (DI...
Article
Electroactive microorganisms can exchange electrons with other cells or conductive interfaces in their extracellular environment. This property opens the way to a broad range of practical biotechnological applications, from manufacturing sustainable chemicals via electrosynthesis, to bioenergy, bioelectronics or improved, low-energy demanding waste...
Article
Favorable interspecies associations prevail in natural microbial assemblages. Some of these favorable associations are co-metabolic dependent partnerships in which extracellular electrons are exchanged between species. For such electron exchange to occur, the cells must exhibit electroactive interfaces and get involved in direct cell-to-cell contac...
Preprint
Full-text available
Microbial-induced corrosion has been extensively studied in pure cultures. However, Fe 0 corrosion by complex environmental communities, and especially the interplay between microbial physiological groups, is still poorly understood. In this study, we combined experimental physiology and metagenomics to explore Fe 0-dependent microbial interactions...
Article
Full-text available
Direct interspecies electron transfer (DIET) via electrically conductive minerals can play a role in the anaerobic oxidation of petroleum hydrocarbons in contaminated sites and can be exploited for the development of new, more effective bioremediation approaches.
Article
Full-text available
Electromicrobiology is an emerging field investigating and exploiting the interaction of microorganisms with insoluble electron donors or acceptors. Some of the most recently categorized electroactive microorganisms became of interest to sustainable bioengineering practices. However, laboratories worldwide typically maintain electroactive microorga...
Article
Syntrophic interspecies electron exchange is essential for the stable functioning of diverse anaerobic microbial communities. Hydrogen/formate interspecies electron transfer (HFIT), in which H2 and/or formate function as diffusible electron carriers, has been considered to be the primary mechanism for electron transfer because most common syntrophs...
Preprint
Full-text available
The co-occurrence of Geobacter and Methanosarcinales is often used as a proxy for the manifestation of direct interspecies electron transfer (DIET) in man-made and natural aquatic environments. We previously reported that not all Geobacter are capable of DIET with Methanosarcina. Here we tested 15 new artificial co-culture combinations with methano...
Article
Full-text available
Plastics and other artificial materials pose new risks to health of the ocean. Anthropogenic debris travels across large distances and is ubiquitous in the water and on the shorelines, yet, observations of its sources, composition, pathways and distributions in the ocean are very sparse and inaccurate. Total amounts of plastics and other man-made...
Article
Full-text available
Maximenko et al. Integrated Marine Debris Observing System Plastics and other artificial materials pose new risks to the health of the ocean. Anthropogenic debris travels across large distances and is ubiquitous in the water and on shorelines, yet, observations of its sources, composition, pathways, and distributions in the ocean are very sparse an...
Article
Full-text available
Direct electron uptake by prokaryotes is a recently described mechanism with a potential application for energy and CO2 storage into value added chemicals. Members of Methanosarcinales, an environmentally and biotechnologically relevant group of methanogens, were previously shown to retrieve electrons from an extracellular electrogenic partner perf...
Preprint
Full-text available
Urban environments are webbed with iron-steel structures above and belowground. Underground, in non-sulfidic environments, it has been suggested that interspecies interactions cause Fe ⁰ corrosion. Particularly, Methanosarcinales were assumed to interact syntrophically with acetogenic bacteria during Fe ⁰ corrosion. Here we challenge this assumptio...
Article
Full-text available
Lake La Cruz is considered a biogeochemical analogue to early Earth marine environments because its water column is depleted in sulfate, but rich in methane and iron, similar to conditions envisaged for much of the Precambrian. Here we show that conductive particles drove the metabolic coupling between electroactive microbial clades from this envir...
Preprint
Full-text available
Microbial induced corrosion of steel structures, used for transport or storage of fuels, chemical weapons or waste radionuclides, is an environmental and economic threat. In non-sulfidic environments, the exact role of methanogens in steel corrosion is poorly understood. From the non-sulfidic, methanogenic sediments of the Baltic Sea corrosive comm...
Article
Full-text available
Direct interspecies electron transfer (DIET) is important in diverse methanogenic environments, but how methanogens participate in DIET is poorly understood. Therefore, the transcriptome of Methanosarcina barkeri grown via DIET in co-culture with Geobacter metallireducens was compared with its transcriptome when grown via H2 interspecies transfer (...
Preprint
Full-text available
Syntrophic interspecies electron exchange is essential for the stable functioning of diverse anaerobic microbial communities. Hydrogen/formate interspecies electron transfer (HFIT), in which H2 and/or formate function as diffusible electron carriers, has been considered to be the primary mechanism for electron sharing because most common syntrophs...
Preprint
Full-text available
Direct electron uptake by prokaryotes is a recently described mechanism with a potential application for energy and CO2 storage into value added chemicals. Members of Methanosarcinales, an environmentally and biotechnologically relevant group of methanogens, were previously shown to retrieve electrons from an extracellular electrogenic partner perf...
Article
Full-text available
Previous studies of acetate-promoted bioremediation of uranium-contaminated aquifers focused on Geobacter because no other microorganisms that can couple the oxidation of acetate with U(VI) reduction had been detected in situ. Monitoring the levels of methyl CoM reductase subunit A (mcrA) transcripts during an acetate-injection field experiment dem...
Article
Full-text available
Cytochrome-to-cytochrome electron transfer and electron transfer along conduits of multiple extracellular magnetite grains are often proposed as strategies for direct interspecies electron transfer (DIET) that do not require electrically conductive pili (e-pili). However, physical evidence for these proposed DIET mechanisms has been lacking. To inv...
Preprint
Full-text available
Lake La Cruz is considered a biogeochemical analogue to early Earth marine environments because its water column is depleted in sulfate, but rich in methane and iron, similar to conditions envisaged for much of the Precambrian. In this early Earth analogue environment, we show that conductive particles establish a tight metabolic coupling between e...
Preprint
Full-text available
Coastal sediments are rich in conductive minerals, which could impact microbial processes for which acetate is a central intermediate. In the methanogenic zone, acetate is consumed by methanogens and/or syntrophic acetate oxidizing (SAO) consortia. SAO consortia live under extreme thermodynamic pressure and their survival depends on successful part...
Article
Full-text available
Previous studies of in situ bioremediation of uranium-contaminated groundwater with acetate injections have focused on the role of Geobacter species in U(VI) reduction because of a lack of other abundant known U(VI)-reducing microorganisms. Monitoring the levels of methyl CoM reductase subunit A (mcrA) transcripts during an acetate-injection field...
Article
Full-text available
Fossil fuels and fossil fuel derived chemicals are limited, non-renewable, and foreseen to run out in the near future. To find viable solutions for the production of renewable fuels and chemicals, significant efforts are being made by the scientific community. For example, some microorganisms have been shown to produce fuels or chemicals using rene...
Article
In anoxic marine sediments, consortia of methane-consuming archaea and sulfate-reducing bacteria oxidize methane. Together, they thereby control methane discharge in a metabolism of global importance. During this cooperative interspecies interaction, known as syntrophy, the excess reducing equivalents released by one species feed the second species...
Article
Full-text available
Nanoscale magnetite can facilitate microbial extracellular electron transfer that plays an important role in biogeochemical cycles, bioremediation and several bioenergy strategies, but the mechanisms for the stimulation of extracellular electron transfer are poorly understood. Further investigation revealed that magnetite attached to the electrical...
Article
Full-text available
Electrodes are unnatural electron acceptors, and it is yet unknown how some Geobacter species evolved to use electrodes as terminal electron acceptors. Analysis of different Geobacter species revealed that they varied in their capacity for current production. Geobacter metallireducens and G. hydrogenophilus generated high current densities (ca. 0.2...
Article
Nano-scale magnetite can facilitate microbial extracellular electron transfer that plays an important role in biogeochemical cycles, bioremediation, and several bioenergy strategies, but the mechanisms for the stimulation of extracellular electron transfer are poorly understood. Further investigation revealed that magnetite attached to the electric...
Article
Full-text available
Biochar, a charcoal-like product of the incomplete combustion of organic materials, is an increasingly popular soil amendment designed to improve soil fertility. We investigated the possibility that biochar could promote direct interspecies electron transfer (DIET) in a manner similar to that previously reported for granular activated carbon (GAC)....
Article
Full-text available
Direct interspecies electron transfer (DIET) is potentially an effective form of syntrophy in methanogenic communities, but little is known about the diversity of methanogens capable of DIET. The ability of Methanosarcina barkeri to participate in DIET was evaluated in coculture with Geobacter metallireducens. Cocultures formed aggregates that shar...
Article
Full-text available
Interspecies exchange of electrons enables a diversity of microbial communities to gain energy from reactions that no one microbe can catalyze. The first recognized strategies for interspecies electron transfer were those that relied on chemical intermediates that are recycled through oxidized and reduced forms. Well-studied examples are interspeci...
Article
Direct interspecies electron transfer (DIET) is potentially an effective form of syntrophy in methanogenic communities, but little is known about the diversity of methanogens capable of DIET. The ability of Methanosarcina barkeri, to participate in DIET was evaluated in co-culture with Geobacter metallireducens. Co-cultures formed aggregates that s...
Article
Full-text available
Geobacter species are of great interest for environmental and biotechnology applications as they can carry out direct electron transfer to insoluble metals or other microorganisms and have the ability to assimilate inorganic carbon. Here, we report on the capability and key enabling metabolic machinery of Geobacter metallireducens GS-15 to carry ou...
Article
Full-text available
Syntrophic associations are central to microbial communities and thus have a fundamental role in the global carbon cycle. Despite biochemical approaches describing the physiological activity of these communities, there has been a lack of a mechanistic understanding of the relationship between complex nutritional and energetic dependencies and their...
Article
Direct interspecies electron transfer (DIET) through biological electrical connections is an alternative to interspecies H2 transfer as a mechanism for electron exchange in syntrophic cultures. However, it has not previously been determined whether electrons received via DIET yield energy to support cell growth. In order to investigate this, co-cul...
Article
Full-text available
The possibility that metatranscriptomic analysis could distinguish between direct interspecies electron transfer (DIET) and H2 interspecies transfer (HIT) in anaerobic communities was investigated by comparing gene transcript abundance in cocultures in which Geobacter sulfurreducens was the electron-accepting partner for either Geobacter metallired...
Article
Full-text available
Granular activated carbon (GAC) is commonly added to methanogenic digesters to enhance conversion of wastes to methane, but the mechanism(s) for GAC's stimulatory effect are poorly understood. GAC has high electrical conductivity and thus it was hypothesized that one mechanism for GAC stimulation of methanogenesis might be to facilitate direct inte...
Article
Full-text available
Direct interspecies electron transfer (DIET) is an alternative to interspecies H2/formate transfer as a mechanism for microbial species to cooperatively exchange electrons during syntrophic metabolism. To understand what specific properties contribute to DIET, studies were conducted with Pelobacter carbinolicus, a close relative of Geobacter metall...
Article
The use of microorganisms as support for reduction of dissolved Pd(II) to immobilized Pd(0) nanoparticles is an environmentally friendly approach for Pd recovery from waste. To better understand and engineer Pd(0) nanoparticle synthesis, one has to consider the mechanisms by which Pd(II) is reduced on microbial surfaces. Escherichia coli, Shewanell...
Article
Full-text available
Members of candidate division OP3 were detected in 16S rRNA gene clone libraries from methanogenic enrichment cultures that utilized limonene as a carbon and energy source. We developed probes for the visualization of OP3 cells. In situ hybridization experiments with newly designed OP3-specific probes [OP3-565 and Eub-338(VI)] revealed abundant sma...
Article
Members of candidate division OP3 were detected in 16S rRNA gene clone libraries from methanogenic enrichment cultures that utilized limonene as a carbon and energy source. We developed probes for the visualization of OP3 cells. In situ hybridization experiments with newly designed OP3-specific probes [OP3-565 and Eub-338(VI)] revealed abundant sma...
Article
Full-text available
Bimetallic nanoparticles are considered the next generation of nanocatalysts with increased stability and catalytic activity. Bio-supported synthesis of monometallic nanoparticles has been proposed as an environmentally friendly alternative to the conventional chemical and physical protocols. In this study we synthesize bimetallic bio-supported Pd-...
Article
Full-text available
Mechanisms for electron transfer within microbial aggregates derived from an upflow anaerobic sludge blanket reactor converting brewery waste to methane were investigated in order to better understand the function of methanogenic consortia. The aggregates were electrically conductive, with conductivities 3-fold higher than the conductivities previo...
Article
Geobacter species specialize in making electrical contacts with extracellular electron acceptors and other organisms. This permits Geobacter species to fill important niches in a diversity of anaerobic environments. Geobacter species appear to be the primary agents for coupling the oxidation of organic compounds to the reduction of insoluble Fe(III...
Article
The increasing demand and limited natural resources for industrially important platinum-group metal (PGM) catalysts render the recovery from secondary sources such as industrial waste economically interesting. In the process of palladium (Pd) recovery, microorganisms have revealed a strong potential. Hitherto, bacteria with the property of dissimil...
Article
The identity of the microorganisms capable of anaerobic p-xylene degradation under denitrifying conditions is hitherto unknown. Here, we report highly enriched cultures of freshwater denitrifying bacteria that grow anaerobically with p-xylene as the sole organic carbon source and electron donor. Long curved rods, with 95% 16S rRNA gene sequence ide...
Article
Full-text available
The anaerobic degradation of hydrocarbons has been intensively explored in the last decade yielding insights into new physiological capabilities and biochemical pathways. However, for a few hydrocarbons, e.g. p-xylene, it proved to be more difficult to enrich microorganisms and to isolate pure strains. Thermodynamically, the mineralization of hydro...

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