Isolation and genomic analysis of " MK1, a Gram-positive, Fe(III)-reducing bacterium from the Soudan Underground Mine, an iron-rich Martian analog site.

The Soudan Underground Mine State Park, found in the Vermilion Iron Range in northern Minnesota, provides access to a ~ 2.7 billion-year-old banded iron formation. Exploratory boreholes drilled between 1958 and 1962 on the 27th level (713 m underground) of the mine intersect calcium and iron-rich brines that have recently been subject to metagenomic analysis and microbial enrichments.

Red-Light-Induced Genetic System for Control of Extracellular Electron Transfer.

Optogenetics is a powerful tool for spatiotemporal control of gene expression. Several light-inducible gene regulators have been developed to function in bacteria, and these regulatory circuits have been ported to new host strains. Here, we developed and adapted a red-light-inducible transcription factor for .

Extracellular organic disulfide reduction by MR-1.

Microbial reduction of organic disulfides affects the macromolecular structure and chemical reactivity of natural organic matter. Currently, the enzymatic pathways that mediate disulfide bond reduction in soil and sedimentary organic matter are poorly understood. In this study, we examined the extracellular reduction of 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) by strain MR-1.

Comparison of phage-derived recombinases for genetic manipulation of species.

The genus contains many members currently being investigated for applications in biodegradation, biopesticides, biocontrol, and synthetic biology. Though several strains have been identified with beneficial properties, chromosomal manipulations to further improve these strains for commercial applications have been limited due to the lack of efficient genetic tools that have been tested across this genus. Here, we test the recombineering efficiencies of five phage-derived recombinases across three biotechnologically relevant strains: KT2440, Pf-5, and CHA0.

The Outer Membrane Cytochrome OmcA Is Essential for Infection of Shewanella oneidensis by a Zebrafish-Associated Bacteriophage.

The microbiota-the mixture of microorganisms in the intestinal tract of animals-plays an important role in host biology. Bacteriophages are a prominent, though often overlooked, component of the microbiota. The mechanisms that phage use to infect susceptible cells associated with animal hosts, and the broader role they could play in determining the substituents of the microbiota, are poorly understood.

Reconstructing electron transfer components from an Fe(II) oxidizing bacterium.

Neutrophilic Fe(II) oxidizing bacteria play an important role in biogeochemical processes and have also received attention for multiple technological applications. These micro-organisms are thought to couple their metabolism with extracellular electron transfer (EET) while oxidizing Fe(II) as electron donor outside the cell. ES-1 is a freshwater chemolithoautotrophic Fe(II) oxidizing bacterium that is challenging to culture and not yet genetically tractable.

PioABC-Dependent Fe(II) Oxidation during Photoheterotrophic Growth on an Oxidized Carbon Substrate Increases Growth Yield.

Microorganisms that carry out Fe(II) oxidation play a major role in biogeochemical cycling of iron in environments with low oxygen. Fe(II) oxidation has been largely studied in the context of autotrophy. Here, we show that the anoxygenic phototroph, Rhodopseudomonas palustris CGA010, carries out Fe(II) oxidation during photoheterotrophic growth with an oxidized carbon source, malate, leading to an increase in cell yield and allowing more carbon to be directed to cell biomass.

The potential for bacteria from carbon-limited deep terrestrial environments to participate in chlorine cycling.

Bacteria capable of dehalogenation via reductive or hydrolytic pathways are ubiquitous. Little is known, however, about the prevalence of bacterial dechlorination in deep terrestrial environments with a limited carbon supply. In this study we analyzed published genomes from three deep terrestrial subsurface sites: a deep aquifer in Western Siberia, the Sanford Underground Research Facility in South Dakota, USA, and the Soudan Underground Iron Mine (SUIM) in Minnesota, USA to determine if there was evidence to suggest that microbial dehalogenation was possible in these environments.

Evidence for Horizontal and Vertical Transmission of Mtr-Mediated Extracellular Electron Transfer among the .

Some bacteria and archaea have evolved the means to use extracellular electron donors and acceptors for energy metabolism, a phenomenon broadly known as extracellular electron transfer (EET). One such EET mechanism is the transmembrane electron conduit MtrCAB, which has been shown to transfer electrons derived from metabolic substrates to electron acceptors, like Fe(III) and Mn(IV) oxides, outside the cell. Although most studies of MtrCAB-mediated EET have been conducted in Shewanella oneidensis MR-1, recent investigations in and species have revealed that the electron-donating proteins that support MtrCAB in are not as representative as previously thought.

Engineering Wired Life: Synthetic Biology for Electroactive Bacteria.

Electroactive bacteria produce or consume electrical current by moving electrons to and from extracellular acceptors and donors. This specialized process, known as extracellular electron transfer, relies on pathways composed of redox active proteins and biomolecules and has enabled technologies ranging from harvesting energy on the sea floor, to chemical sensing, to carbon capture. Harnessing and controlling extracellular electron transfer pathways using bioengineering and synthetic biology promises to heighten the limits of established technologies and open doors to new possibilities.

Oligo-heterotrophic Activity of Creates an Indirect Fe(II) Oxidation Phenotype in Gradient Tubes.

Autotrophic bacteria utilizing Fe(II) as their energy and electron sources for growth affect multiple biogeochemical cycles. Some chemoheterotrophic bacteria have also been considered to exhibit an Fe(II) oxidation phenotype. For example, several Marinobacter strains have been reported to oxidize Fe(II) based on formation of oxidized iron bands in semi-solid gradient tubes that produce opposing concentration gradients of Fe(II) and oxygen.

Engineering Biological Electron Transfer and Redox Pathways for Nanoparticle Synthesis.

Many species of bacteria are naturally capable of types of electron transport not observed in eukaryotic cells. Some species live in environments containing heavy metals not typically encountered by cells of multicellular organisms, such as arsenic, cadmium, and mercury, leading to the evolution of enzymes to deal with these environmental toxins. Bacteria also inhabit a variety of extreme environments, and are capable of respiration even in the absence of oxygen as a terminal electron acceptor.

Evidence of a Streamlined Extracellular Electron Transfer Pathway from Biofilm Structure, Metabolic Stratification, and Long-Range Electron Transfer Parameters.

A strain of Geobacter sulfurreducens, an organism capable of respiring solid extracellular substrates, lacking four of five outer membrane cytochrome complexes ( strain) grows faster and produces greater current density than the wild type grown under identical conditions. To understand cellular and biofilm modifications in the strain responsible for this increased performance, biofilms grown using electrodes as terminal electron acceptors were sectioned and imaged using electron microscopy to determine changes in thickness and cell density, while parallel biofilms incubated in the presence of nitrogen and carbon isotopes were analyzed using NanoSIMS (nanoscale secondary ion mass spectrometry) to quantify and localize anabolic activity. Long-distance electron transfer parameters were measured for wild-type and biofilms spanning 5-μm gaps.

Survival of the first rather than the fittest in a Shewanella electrode biofilm.

For natural selection to operate there must exist heritable variation among individuals that affects their survival and reproduction. Among free-living microbes, where differences in growth rates largely define selection intensities, competitive exclusion is common. However, among surface attached communities, these dynamics become less predictable.

Novel Microbial Groups Drive Productivity in an Archean Iron Formation.

Deep subsurface environments are decoupled from Earth's surface processes yet diverse, active, and abundant microbial communities thrive in these isolated environments. Microbes inhabiting the deep biosphere face unique challenges such as electron donor/acceptor limitations, pore space/fracture network limitations, and isolation from other microbes within the formation. Of the few systems that have been characterized, it is apparent that nutrient limitations likely facilitate diverse microbe-microbe interactions (i.

Engineering Cooperation in an Anaerobic Coculture.

Over the past century, microbiologists have studied organisms in pure culture, yet it is becoming increasingly apparent that the majority of biological processes rely on multispecies cooperation and interaction. While little is known about how such interactions permit cooperation, even less is known about how cooperation arises. To study the emergence of cooperation in the laboratory, we constructed both a commensal community and an obligate mutualism using the previously noninteracting bacteria and Incorporation of a glycerol utilization plasmid (pGUT2) enabled to metabolize glycerol and produce acetate as a carbon source for , establishing a cross-feeding, commensal coculture.

Engineering lithoheterotrophy in an obligate chemolithoautotrophic Fe(II) oxidizing bacterium.

Neutrophilic Fe(II) oxidizing bacteria like Mariprofundus ferrooxydans are obligate chemolithoautotrophic bacteria that play an important role in the biogeochemical cycling of iron and other elements in multiple environments. These bacteria generally exhibit a singular metabolic mode of growth which prohibits comparative "omics" studies. Furthermore, these bacteria are considered non-amenable to classical genetic methods due to low cell densities, the inability to form colonies on solid medium, and production of copious amounts of insoluble iron oxyhydroxides as their metabolic byproduct.

Electrolocation? The evidence for redox-mediated taxis in Shewanella oneidensis.

Shewanella oneidensis is a dissimilatory metal reducing bacterium and model for extracellular electron transfer (EET), a respiratory mechanism in which electrons are transferred out of the cell. In the last 10 years, migration to insoluble electron acceptors for EET has been shown to be nonrandom and tactic, seemingly in the absence of molecular or energy gradients that typically allow for taxis. As the ability to sense, locate, and respire electrodes has applications in bioelectrochemical technology, a better understanding of taxis in S.

Plasmid copy number variation of a modular vector set in Shewanella oneidensis MR-1.

To advance synthetic biology approaches that utilize S. oneidensis as host for biotechnology applications, we have investigated the variation in plasmid copy number of a modular vector set resulting from distinct origins of replication under different conditions. The replicons yielded a ≈9X-fold range for plasmid copy number variation in S.

A Hybrid Extracellular Electron Transfer Pathway Enhances the Survival of Vibrio natriegens.

is the fastest-growing microorganism discovered to date, making it a useful model for biotechnology and basic research. While it is recognized for its rapid aerobic metabolism, less is known about anaerobic adaptations in or how the organism survives when oxygen is limited. Here, we describe and characterize extracellular electron transfer (EET) in , a metabolism that requires movement of electrons across protective cellular barriers to reach the extracellular space.

Extracellular electron transfer-dependent anaerobic oxidation of ammonium by anammox bacteria.

Anaerobic ammonium oxidation (anammox) bacteria contribute significantly to the global nitrogen cycle and play a major role in sustainable wastewater treatment. Anammox bacteria convert ammonium (NH) to dinitrogen gas (N) using intracellular electron acceptors such as nitrite (NO) or nitric oxide (NO). However, it is still unknown whether anammox bacteria have extracellular electron transfer (EET) capability with transfer of electrons to insoluble extracellular electron acceptors.

Evidence for auxiliary anaerobic metabolism in obligately aerobic Zetaproteobacteria.

Zetaproteobacteria are obligate chemolithoautotrophs that oxidize Fe(II) as an electron and energy source, and play significant roles in nutrient cycling and primary production in the marine biosphere. Zetaproteobacteria thrive under microoxic conditions near oxic-anoxic interfaces, where they catalyze Fe(II) oxidation faster than the abiotic reaction with oxygen. Neutrophilic Fe(II) oxidizing bacteria produce copious amounts of insoluble iron oxyhydroxides as a by-product of their metabolism.

NosP Signaling Modulates the NO/H-NOX-Mediated Multicomponent c-Di-GMP Network and Biofilm Formation in .

Biofilms form when bacteria aggregate in a self-secreted exopolysaccharide matrix; they are resistant to antibiotics and implicated in disease. Nitric oxide (NO) is known to mediate biofilm formation in many bacteria via ligation to H-NOX (heme-NO/oxygen binding) domains. Most NO-responsive bacteria, however, lack H-NOX domain-containing proteins.