@article {3063,
	title = {Correlation of Key Physiological Properties of  Isolates with Environment of Origin.},
	journal = {Appl Environ Microbiol},
	volume = {87},
	year = {2021},
	month = {2021 Jun 11},
	pages = {e0073121},
	abstract = {<p>It is known that the physiology of  species can differ significantly, but the ecological impact of these differences is unclear. We recovered two strains of  from two different ecosystems with a similar enrichment and isolation method. Both strains had the same ability to metabolize organic substrates and participate in direct interspecies electron transfer but also had major physiological differences. Strain DH-1, which was isolated from an anaerobic digester, used H as an electron donor. Genome analysis indicated that it lacks an Rnf complex and conserves energy from acetate metabolism via intracellular H cycling. In contrast, strain DH-2, a subsurface isolate, lacks hydrogenases required for H uptake and cycling and has an Rnf complex for energy conservation when growing on acetate. Further analysis of the genomes of previously described isolates, as well as phylogenetic and metagenomic data on uncultured  in anaerobic digesters and diverse soils and sediments, revealed a physiological dichotomy that corresponded with environment of origin. The physiology of type I  revolves around H production and consumption. In contrast, type II  species eschew H and have genes for an Rnf complex and the multiheme, membrane-bound -type cytochrome MmcA, shown to be essential for extracellular electron transfer. The distribution of  species in diverse environments suggests that the type I H-based physiology is well suited for high-energy environments, like anaerobic digesters, whereas type II Rnf/cytochrome-based physiology is an adaptation to the slower, steady-state carbon and electron fluxes common in organic-poor anaerobic soils and sediments.  Biogenic methane is a significant greenhouse gas, and the conversion of organic wastes to methane is an important bioenergy process.  species play an important role in methane production in many methanogenic soils and sediments as well as anaerobic waste digesters. The studies reported here emphasize that the genus  is composed of two physiologically distinct groups. This is important to recognize when interpreting the role of  in methanogenic environments, especially regarding H metabolism. Furthermore, the finding that type I  species predominate in environments with high rates of carbon and electron flux and that type II  species predominate in lower-energy environments suggests that evaluating the relative abundance of type I and type II  may provide further insights into rates of carbon and electron flux in methanogenic environments.</p>},
	keywords = {Acetates, Anaerobiosis, Bioreactors, Ecosystem, Electron Transport, Ethanol, Genome, Archaeal, Hydrogen, Methane, Methanosarcina, Phylogeny},
	issn = {1098-5336},
	doi = {10.1128/AEM.00731-21},
	author = {Zhou, Jinjie and Holmes, Dawn E and Tang, Hai-Yan and Lovley, Derek R}
}
@article {3072,
	title = {Syntrophus conductive pili demonstrate that common hydrogen-donating syntrophs can have a direct electron transfer option.},
	journal = {ISME J},
	volume = {14},
	year = {2020},
	month = {2020 Mar},
	pages = {837-846},
	abstract = {<p>Syntrophic interspecies electron exchange is essential for the stable functioning of diverse anaerobic microbial communities. Hydrogen/formate interspecies electron transfer (HFIT), in which H and/or formate function as diffusible electron carriers, has been considered to be the primary mechanism for electron transfer because most common syntrophs were thought to lack biochemical components, such as electrically conductive pili (e-pili), necessary for direct interspecies electron transfer (DIET). Here we report that Syntrophus aciditrophicus, one of the most intensively studied microbial models for HFIT, produces e-pili and can grow via DIET. Heterologous expression of the putative S. aciditrophicus type IV pilin gene in Geobacter sulfurreducens yielded conductive pili of the same diameter (4 nm) and conductance of the native S. aciditrophicus pili and enabled long-range electron transport in G. sulfurreducens. S. aciditrophicus lacked abundant c-type cytochromes often associated with DIET. Pilin genes likely to yield e-pili were found in other genera of hydrogen/formate-producing syntrophs. The finding that DIET is a likely option for diverse syntrophs that are abundant in many anaerobic environments necessitates a reexamination of the paradigm that HFIT is the predominant mechanism for syntrophic electron exchange within anaerobic microbial communities of biogeochemical and practical significance.</p>},
	keywords = {Deltaproteobacteria, Electric Conductivity, Electron Transport, Electrons, Fimbriae Proteins, Fimbriae, Bacterial, Formates, Geobacter, Hydrogen},
	issn = {1751-7370},
	doi = {10.1038/s41396-019-0575-9},
	author = {Walker, David J F and Nevin, Kelly P and Holmes, Dawn E and Rotaru, Amelia-Elena and Ward, Joy E and Woodard, Trevor L and Zhu, Jiaxin and Ueki, Toshiyuki and Nonnenmann, Stephen S and McInerney, Michael J and Lovley, Derek R}
}
@article {581,
	title = {Geoglobus ahangari gen. nov., sp. nov., a novel hyperthermophilic archaeon capable of oxidizing organic acids and growing autotrophically on hydrogen with Fe(III) serving as the sole electron acceptor.},
	journal = {Int J Syst Evol Microbiol},
	volume = {52},
	year = {2002},
	month = {2002 May},
	pages = {719-28},
	abstract = {A novel, regular to irregular, coccoid-shaped, anaerobic, Fe(III)-reducing microorganism was isolated from the Guaymas Basin hydrothermal system at a depth of 2000 m. Isolation was carried out with a new technique using Fe(III) oxide as the electron acceptor for the recovery of colonies on solid medium. The isolate, designated strain 234T, was strictly anaerobic and exhibited a tumbling motility. The cells had a single flagellum. Strain 234T grew at temperatures between 65 and 90 degrees C, with an optimum at about 88 degrees C. The optimal salt concentration for growth was around 19 g l(-1). The isolate was capable of growth with H2 as the sole electron donor coupled to the reduction of Fe(III) without the need for an organic carbon source. This is the first example of a dissimilatory Fe(III)-reducing micro-organism capable of growing autotrophically on hydrogen. In addition to molecular hydrogen, strain 234T oxidizes pyruvate, acetate, malate, succinate, peptone, formate, fumarate, yeast extract, glycerol, isoleucine, arginine, serine, glutamine, asparagine, stearate, palmitate, valerate, butyrate and propionate with the reduction of Fe(III). This isolate is the first example of a hyperthermophile capable of oxidizing long-chain fatty acids anaerobically. Isolate 234T grew exclusively with Fe(III) as the sole electron acceptor. The G+C content was 58.7 mol\%. Based on detailed analysis of its 16S rDNA sequence, G+C content, distinguishing physiological features and metabolism, strain 234T is proposed to represent a novel genus within the Archaeoglobales. The name proposed for strain 234T is Geoglobus ahangari gen. nov., sp. nov..},
	keywords = {Anaerobiosis, Archaea, Bacterial Typing Techniques, DNA, Ribosomal, Electron Transport, Fatty Acids, Ferric Compounds, Hot Temperature, Hydrogen, Molecular Sequence Data, Oxidation-Reduction, Phylogeny, RNA, Ribosomal, 16S, Sequence Analysis, DNA, Water Microbiology},
	issn = {1466-5026},
	author = {Kashefi, Kazem and Tor, Jason M and Holmes, Dawn E and Gaw Van Praagh, Catherine V and Reysenbach, Anna-Louise and Lovley, Derek R}
}
