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Full-Text Articles in Life Sciences
Graphite Electrode As A Sole Electron Donor For Reductive Dechlorination Of Tetrachlorethene By Geobacter Lovleyi, Derek Lovley, Sarah M. Strycharz, Trevor L. Woodard, Jessica P. Johnson, Kelly P. Nevin, Robert A. Stanford, Frank E. Lӧffler
Graphite Electrode As A Sole Electron Donor For Reductive Dechlorination Of Tetrachlorethene By Geobacter Lovleyi, Derek Lovley, Sarah M. Strycharz, Trevor L. Woodard, Jessica P. Johnson, Kelly P. Nevin, Robert A. Stanford, Frank E. Lӧffler
Derek Lovley
The possibility that graphite electrodes can serve as the direct electron donor for microbially catalyzed reductive dechlorination was investigated with Geobacter lovleyi. In an initial evaluation of whether G. lovleyi could interact electronically with graphite electrodes, cells were provided with acetate as the electron donor and an electrode as the sole electron acceptor. Current was produced at levels that were ca. 10-fold lower than those previously reported for Geobacter sulfurreducens under similar conditions, and G. lovleyi anode biofilms were correspondingly thinner. When an electrode poised at −300 mV (versus a standard hydrogen electrode) was provided as the electron donor, G. …
Highly Conserved Genes In Geobacter Species With Expression Patterns Indicative Of Acetate Limitation, Derek Lovley, Carla Risso, Barbara A. Methé, Hila Elifantz, Dawn E. Holmes
Highly Conserved Genes In Geobacter Species With Expression Patterns Indicative Of Acetate Limitation, Derek Lovley, Carla Risso, Barbara A. Methé, Hila Elifantz, Dawn E. Holmes
Derek Lovley
Analysis of the genome of Geobacter sulfurreducens revealed four genes encoding putative symporters with homology to ActP, an acetate transporter in Escherichia coli. Three of these genes, aplA, aplB and aplC, are highly similar (over 90 % identical) and fell within a tight phylogenetic cluster (Group I) consisting entirely of Geobacter homologues. Transcript levels for all three genes increased in response to acetate limitation. The fourth gene, aplD, is phylogenetically distinct (Group II) and its expression was not influenced by acetate availability. Deletion of any one of the three genes in Group I did not significantly affect acetate-dependent growth, suggesting …
Genome-Wide Gene Expression Patterns And Growth Requirements Suggest That Pelobacter Carbinolicus Reduces Fe(Iii) Indirectly Via Sulfide Production, Derek Lovley, Shelley A. Haveman, Raymond J. Didonato Jr, Laura Villanueva, Evgenya S. Shelobolina, Bradley L. Postier, Bo Xu, Anna Liu
Genome-Wide Gene Expression Patterns And Growth Requirements Suggest That Pelobacter Carbinolicus Reduces Fe(Iii) Indirectly Via Sulfide Production, Derek Lovley, Shelley A. Haveman, Raymond J. Didonato Jr, Laura Villanueva, Evgenya S. Shelobolina, Bradley L. Postier, Bo Xu, Anna Liu
Derek Lovley
Although Pelobacter species are closely related to Geobacter species, recent studies suggested that Pelobacter carbinolicus may reduce Fe(III) via a different mechanism because it lacks the outer-surface c-type cytochromes that are required for Fe(III) reduction by Geobacter sulfurreducens. Investigation into the mechanisms for Fe(III) reduction demonstrated that P. carbinolicus had growth yields on both soluble and insoluble Fe(III) consistent with those of other Fe(III)-reducing bacteria. Comparison of whole-genome transcript levels during growth on Fe(III) versus fermentative growth demonstrated that the greatest apparent change in gene expression was an increase in transcript levels for four contiguous genes. These genes encode two …
The Degree Of Redundancy In Metabolic Genes Is Linked To Mode Of Metabolism, Derek Lovley, Radhakrishnan Mahadevan
The Degree Of Redundancy In Metabolic Genes Is Linked To Mode Of Metabolism, Derek Lovley, Radhakrishnan Mahadevan
Derek Lovley
An understanding of the factors favoring the maintenance of duplicate genes in microbial genomes is essential for developing models of microbial evolution. A genome-scale flux-balance analysis of the metabolic network of Saccharomyces cerevisiae has suggested that gene duplications primarily provide increased enzyme dosage to enhance metabolic flux because the incidence of gene duplications in essential genes is no higher than that in nonessential genes. Here, we used genome-scale metabolic models to analyze the extent of genetic and biochemical redundancy in prokaryotes that are either specialists, with one major mode of energy generation, or generalists, which have multiple metabolic strategies for …
Elucidation Of An Alternate Isoleucine Biosynthesis Pathway In Geobacter Sulfurreducens, Derek Lovley, Carla Risso, Stephen J. Van Dien, Amber Orloff, Maddalena V. Coppi
Elucidation Of An Alternate Isoleucine Biosynthesis Pathway In Geobacter Sulfurreducens, Derek Lovley, Carla Risso, Stephen J. Van Dien, Amber Orloff, Maddalena V. Coppi
Derek Lovley
The central metabolic model for Geobacter sulfurreducens included a single pathway for the biosynthesis of isoleucine that was analogous to that of Escherichia coli, in which the isoleucine precursor 2-oxobutanoate is generated from threonine. 13C labeling studies performed in G. sulfurreducens indicated that this pathway accounted for a minor fraction of isoleucine biosynthesis and that the majority of isoleucine was instead derived from acetyl-coenzyme A and pyruvate, possibly via the citramalate pathway. Genes encoding citramalate synthase (GSU1798), which catalyzes the first dedicated step in the citramalate pathway, and threonine ammonia-lyase (GSU0486), which catalyzes the conversion of threonine to 2-oxobutanoate, were …
Comparative Genomics Of Geobacter Chemotaxis Genes Reveals Diverse Signaling Function, Derek Lovley, Hoa T. Tran, Julia Krushkal, Frances M. Antommattei, Robert M. Weis
Comparative Genomics Of Geobacter Chemotaxis Genes Reveals Diverse Signaling Function, Derek Lovley, Hoa T. Tran, Julia Krushkal, Frances M. Antommattei, Robert M. Weis
Derek Lovley
Background Geobacter species are δ-Proteobacteria and are often the predominant species in a variety of sedimentary environments where Fe(III) reduction is important. Their ability to remediate contaminated environments and produce electricity makes them attractive for further study. Cell motility, biofilm formation, and type IV pili all appear important for the growth of Geobacter in changing environments and for electricity production. Recent studies in other bacteria have demonstrated that signaling pathways homologous to the paradigm established for Escherichia coli chemotaxis can regulate type IV pili-dependent motility, the synthesis of flagella and type IV pili, the production of extracellular matrix material, and …
Computational And Experimental Analysis Of Redundancy In The Central Metabolism Of Geobacter Sulfurreducens, Derek Lovley, Daniel Segura, Radhakrishnan Mahadevan, Katy Juárez
Computational And Experimental Analysis Of Redundancy In The Central Metabolism Of Geobacter Sulfurreducens, Derek Lovley, Daniel Segura, Radhakrishnan Mahadevan, Katy Juárez
Derek Lovley
Previous model-based analysis of the metabolic network of Geobacter sulfurreducens suggested the existence of several redundant pathways. Here, we identified eight sets of redundant pathways that included redundancy for the assimilation of acetate, and for the conversion of pyruvate into acetyl-CoA. These equivalent pathways and two other sub-optimal pathways were studied using 5 single-gene deletion mutants in those pathways for the evaluation of the predictive capacity of the model. The growth phenotypes of these mutants were studied under 12 different conditions of electron donor and acceptor availability. The comparison of the model predictions with the resulting experimental phenotypes indicated that …