@article {3057,
	title = {Generation of High Current Densities in Geobacter sulfurreducens Lacking the Putative Gene for the PilB Pilus Assembly Motor.},
	journal = {Microbiol Spectr},
	volume = {9},
	year = {2021},
	month = {2021 Oct 31},
	pages = {e0087721},
	abstract = {<p>Geobacter sulfurreducens is commonly employed as a model for the study of extracellular electron transport mechanisms in the  species. Deletion of , which is known to encode the pilus assembly motor protein for type IV pili in other bacteria, has been proposed as an effective strategy for evaluating the role of electrically conductive pili (e-pili) in G. sulfurreducens extracellular electron transfer. In those studies, the inhibition of e-pili expression associated with  deletion was not demonstrated directly but was inferred from the observation that  deletion mutants produced lower current densities than wild-type cells. Here, we report that deleting  did not diminish current production. Conducting probe atomic force microscopy revealed filaments with the same diameter and similar current-voltage response as e-pili harvested from wild-type G. sulfurreducens or when e-pili are expressed heterologously from the G. sulfurreducens pilin gene in Escherichia coli. Immunogold labeling demonstrated that a G. sulfurreducens strain expressing a pilin monomer with a His tag continued to express His tag-labeled filaments when  was deleted. These results suggest that a reinterpretation of the results of previous studies on G. sulfurreducens  deletion strains may be necessary.  Geobacter sulfurreducens is a model microbe for the study of biogeochemically and technologically significant processes, such as the reduction of Fe(III) oxides in soils and sediments, bioelectrochemical applications that produce electric current from waste organic matter or drive useful processes with the consumption of renewable electricity, direct interspecies electron transfer in anaerobic digestors and methanogenic soils and sediments, and metal corrosion. Elucidating the phenotypes associated with gene deletions is an important strategy for determining the mechanisms for extracellular electron transfer in G. sulfurreducens. The results reported here demonstrate that we cannot replicate the key phenotype reported for a gene deletion that has been central to the development of models for long-range electron transport in G. sulfurreducens.</p>},
	keywords = {Bacterial Proteins, Electric Conductivity, Electron Transport, Fimbriae Proteins, Fimbriae, Bacterial, Gene Deletion, Geobacter, Geologic Sediments, Microscopy, Atomic Force, Oxidoreductases},
	issn = {2165-0497},
	doi = {10.1128/Spectrum.00877-21},
	author = {Ueki, Toshiyuki and Walker, David J F and Nevin, Kelly P and Ward, Joy E and Woodard, Trevor L and Nonnenmann, Stephen S and Lovley, Derek R}
}
@article {3150,
	title = {A genetic system for Clostridium ljungdahlii: a chassis for autotrophic production of biocommodities and a model homoacetogen.},
	journal = {Appl Environ Microbiol},
	volume = {79},
	year = {2013},
	month = {2013 Feb},
	pages = {1102-9},
	abstract = {<p>Methods for genetic manipulation of Clostridium ljungdahlii are of interest because of the potential for production of fuels and other biocommodities from carbon dioxide via microbial electrosynthesis or more traditional modes of autotrophy with hydrogen or carbon monoxide as the electron donor. Furthermore, acetogenesis plays an important role in the global carbon cycle. Gene deletion strategies required for physiological studies of C. ljungdahlii have not previously been demonstrated. An electroporation procedure for introducing plasmids was optimized, and four different replicative origins for plasmid propagation in C. ljungdahlii were identified. Chromosomal gene deletion via double-crossover homologous recombination with a suicide vector was demonstrated initially with deletion of the gene for FliA, a putative sigma factor involved in flagellar biogenesis and motility in C. ljungdahlii. Deletion of fliA yielded a strain that lacked flagella and was not motile. To evaluate the potential utility of gene deletions for functional genomic studies and to redirect carbon and electron flow, the genes for the putative bifunctional aldehyde/alcohol dehydrogenases, adhE1 and adhE2, were deleted individually or together. Deletion of adhE1, but not adhE2, diminished ethanol production with a corresponding carbon recovery in acetate. The double deletion mutant had a phenotype similar to that of the adhE1-deficient strain. Expression of adhE1 in trans partially restored the capacity for ethanol production. These results demonstrate the feasibility of genetic investigations of acetogen physiology and the potential for genetic manipulation of C. ljungdahlii to optimize autotrophic biocommodity production.</p>},
	keywords = {Clostridium, Electroporation, Gene Deletion, Genetic Complementation Test, Genetic Vectors, Genetics, Microbial, Metabolic Engineering, Molecular Biology, Plasmids, Transformation, Bacterial},
	issn = {1098-5336},
	doi = {10.1128/AEM.02891-12},
	author = {Leang, Ching and Ueki, Toshiyuki and Nevin, Kelly P and Lovley, Derek R}
}
@article {512,
	title = {Computational prediction of RpoS and RpoD regulatory sites in Geobacter sulfurreducens using sequence and gene expression information.},
	journal = {Gene},
	volume = {384},
	year = {2006},
	month = {2006 Dec 15},
	pages = {73-95},
	abstract = {RpoS, the sigma S subunit of RNA polymerase, is vital during the growth and survival of Geobacter sulfurreducens under conditions typically encountered in its native subsurface environments. We investigated the conservation of sites that may be important for RpoS function in G. sulfurreducens. We also employed sequence information and expression microarray data to predict G. sulfurreducens genome sites that may be related to RpoS regulation. Hierarchical clustering identified three clusters of significantly downregulated genes in the rpoS deletion mutant. The search for conserved overrepresented motifs in co-regulated operons identified likely -35 and -10 promoter elements upstream of a number of functionally important G. sulfurreducens operons that were downregulated in the rpoS deletion mutant. Putative -35/-10 promoter elements were also identified in the G. sulfurreducens genome using sequence similarity searches to matrices of -35/-10 promoter elements found in G. sulfurreducens and in Escherichia coli. Due to a sufficient degree of sequence similarity between -35/-10 promoter elements for RpoS, RpoD, and other sigma factors, both the sequence similarity searches and the search for conserved overrepresented motifs using microarray data may identify promoter elements for both RpoS and other sigma factors.},
	keywords = {Amino Acid Sequence, Bacterial Proteins, Base Sequence, Citrates, Computational Biology, Conserved Sequence, DNA-Directed RNA Polymerases, Escherichia coli, Escherichia coli Proteins, Gene Deletion, Gene Expression Profiling, Gene Expression Regulation, Bacterial, Genes, Bacterial, Genome, Bacterial, Geobacter, Molecular Sequence Data, Oligonucleotide Array Sequence Analysis, Operon, Promoter Regions, Genetic, Sigma Factor, Transcription, Genetic},
	issn = {0378-1119},
	doi = {10.1016/j.gene.2006.06.025},
	author = {Yan, Bin and N{\'u}{\~n}ez, Cinthia and Ueki, Toshiyuki and Esteve-N{\'u}{\~n}ez, Abraham and Puljic, Marko and Adkins, Ronald M and Meth{\'e}, Barbara A and Lovley, Derek R and Krushkal, Julia}
}
