M. Keyhan

Payload hardware and experimental protocol development to enable future testing of the effect of space microgravity on the resistance to gentamicin of uropathogenic Escherichia coli and its σs-deficient mutant

A. Matin, J.-H. Wang, M. Keyhan, Rachna Singh et autres

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Payload Hardware and Experimental Protocol for Testing the Effect of Space Microgravity on the Resistance to Gentamicin of Stationary-Phase Uropathogenic Escherichia Coli and Its Sigma (sup S)-Deficient Mutant

Abdul Matin, J.-H. Wang, M. Keyhan, Rachna Singh et autres

Human immune response is compromised and bacteria can become more antibiotic resistant in space microgravity (MG). We report that under low-shear modeled microgravity (LSMMG) stationary-phase uropathogenic Escherichia coli (UPEC) become more resistant to gentamicin (Gm). UPEC causes urinary tract infections (UTIs), reported …

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EcAMSat: Effect of Space-Flight on Antibiotic Resistance of a Pathogenic Bacterium and its Genetic Basis

Abdul Matin, M Benoit, Matthew Chin, Tori Chinn et autres

Human immune response is compromised in space and incidence of urinary tract infections (UTI) in astronauts has been reported. We have found that the causative agent of UTI, the uropathogenic Escherichia coli, becomes more resistant to gentamicin (Gm), which is commonly used …

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Sigma S-Dependent Antioxidant Defense Protects Stationary-Phase Escherichia coli against the Bactericidal Antibiotic Gentamicin

Jing-Hung Wang, Rachna Singh, M Benoit, M. Keyhan et autres

Stationary-phase bacteria are important in disease. The σ(s)-regulated general stress response helps them become resistant to disinfectants, but the role of σ(s) in bacterial antibiotic resistance has not been elucidated. Loss of σ(s) rendered stationary-phase Escherichia coli more sensitive to the bactericidal …

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Role of the rapA Gene in Controlling Antibiotic Resistance of Escherichia coli Biofilms

Susan V. Lynch, Lance J. Dixon, M Benoit, Eoin Brodie et autres

By using a high-throughput screening method, a mutant of a uropathogenic Escherichia coli strain affected in the rapA gene was isolated. The mutant formed normal-architecture biofilms but showed decreased penicillin G resistance, although the mutation did not affect planktonic cell resistance. Transcriptome …

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Biomolecular Strategy To Decrease ChromateToxicity To Remediating Bacteria

David F. Ackerley, Claudio F. González, M. Keyhan, Robert C. Blake et autres

Cr(VI) (chromate) is a widespread environmental pollutant, and a constant threat to drinking water supplies. It is soluble, toxic and carcinogenic. Bacteria can remediate it by reducing it to insoluble Cr(III). Chromate, however, is toxic also to the remediating bacteria, hampering their …

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Mechanism of chromate reduction by the Escherichia coli protein, NfsA, and the role of different chromate reductases in minimizing oxidative stress during chromate reduction

David F. Ackerley, C. F. Gonzalez, M. Keyhan, Robert C. Blake et autres

Chromate [Cr(VI)] is a serious environmental pollutant, which is amenable to bacterial bioremediation. NfsA, the major oxygen-insensitive nitroreductase of Escherichia coli, is a flavoprotein that is able to reduce chromate to less soluble and less toxic Cr(III). We show that this process …

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Chromate-Reducing Properties of Soluble Flavoproteins from Pseudomonas putida and Escherichia coli

David F. Ackerley, C. F. Gonzalez, C. H. Park, Robert C. Blake et autres

Cr(VI) (chromate) is a toxic, soluble environmental contaminant. Bacteria can reduce chromate to the insoluble and less toxic Cr(III), and thus chromate bioremediation is of interest. Genetic and protein engineering of suitable enzymes can improve bacterial bioremediation. Many bacterial enzymes catalyze one-electron …

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Targets of improvement in bacterial chromate bioremediation.

M. Keyhan, David F. Ackerley, A. Matin, M. Pellei et autres

Cr(VI) (chromate) is a widespread, toxic and soluble environmental con- taminant. Bacteria can reduce chromate to insoluble and less toxic Cr(III), and thus chromate bioremediation is of interest. Genetic and protein engineering of suitable enzymes can improve bacterial bioremediation. However, many fundamental …

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Tetracycline Rapidly Reaches All the Constituent Cells of Uropathogenic Escherichia coli Biofilms

Gregory G. Stone, Peter J. Wood, Lance J. Dixon, M. Keyhan et autres

We have developed a method for visualizing Escherichia coli cells that are exposed to tetracycline in a biofilm, based on a previous report that liposomes containing the E. coli TetR(B) protein fluoresce when exposed to this antibiotic. By our method, cells devoid …

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Purification to Homogeneity and Characterization of a Novel Pseudomonas putida Chromate Reductase

C. H. Park, M. Keyhan, Bruce W. Wielinga, Scott Fendorf et autres

Cr(VI) (chromate) is a widespread environmental contaminant. Bacterial chromate reductases can convert soluble and toxic chromate to the insoluble and less toxic Cr(III). Bioremediation can therefore be effective in removing chromate from the environment, especially if the bacterial propensity for such removal …

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The G‐protein FlhF has a role in polar flagellar placement and general stress response induction in Pseudomonas putida

Suada Pandža, Margot Baetens, C. H. Park, Timothy Au et autres

The flhF gene of Pseudomonas putida, which encodes a GTP-binding protein, is part of the flagellar-motility-chemotaxis operon. Its disruption leads to a random flagellar arrangement in the mutant (MK107) and loss of directional motility in contrast to the wild type, which has …

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