Quantifying the membrane potential during E. coli growth stages

Bot, Corina; Prodan, Camelia

doi:10.1016/j.bpc.2009.11.005

Cited by 67 publications

(51 citation statements)

References 32 publications

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“…These substates were examined at positive pipette potentials (corresponding to negative membrane potentials in our recordings) because the physiological membrane potential of E. coli is estimated to be around À 150 mV (ref. 41), and substates at positive pipette potentials are easier to distinguish than at negative potentials. Furthermore, there are very few reports of MscS subconducting behaviour at positive pipette potentials.…”

Section: Resultsmentioning

confidence: 99%

Selectivity mechanism of the mechanosensitive channel MscS revealed by probing channel subconducting states

et al. 2013

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The mechanosensitive channel of small conductance (MscS) has been characterized at both functional and structural levels and has an integral role in the protection of bacterial cells against hypoosmotic shock. Here we investigate the role that the cytoplasmic domain has in MscS channel function by recording wild-type and mutant MscS single-channel activity in liposome patches. We report that MscS preferentially resides in subconducting states at hyperpolarising potentials when Ca 2 þ and Ba 2 þ ions are the major permeant cations. In addition, our results indicate that charged residues proximal to the seven vestibular portals and their electrostatic interactions with permeating cations determine selectivity and regulate the conductance of MscS and potentially other channels belonging to the MscS subfamily. Furthermore, our findings suggest a role for mechanosensitive channels in bacterial calcium regulation, indicative of functions other than protection against osmolarity changes that these channels possibly fulfil in bacteria.

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Section: Resultsmentioning

confidence: 99%

Selectivity mechanism of the mechanosensitive channel MscS revealed by probing channel subconducting states

et al. 2013

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“…Thus, formate is disproportionated when conditions have changed in favor of increasing the free energy of the reaction. In addition, it is also important to remember that the transmembrane electrochemical gradient is lower in late-than in early-stage fermentation (39); thus, the reaction free energy required to power proton translocation would be lower at this time. Indeed, the genetics beautifully complement the chemistry in this system, because the genes encoding the FHL complex are not expressed until the environmental conditions are correct for the reaction to take place (14).…”

Section: Discussionmentioning

confidence: 99%

Bacterial formate hydrogenlyase complex

McDowall

Murphy

Haumann

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

217

238

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Significance The isolation of an active formate hydrogenlyase is a breakthrough in understanding the molecular basis of bacterial hydrogen production. For over 100 years, Escherichia coli has been known to evolve H 2 when cultured under fermentative conditions. Glucose is metabolized to formate, which is then oxidized to CO 2 with the concomitant reduction of protons to H 2 by a single complex called formate hydrogenlyase, which had been genetically, but never biochemically, characterized. In this study, innovative molecular biology and electrochemical experiments reveal a hydrogenase enzyme with the unique ability to sustain H 2 production even under high partial pressures of H 2 . Harnessing bacterial H 2 production offers the prospect of a source of fully renewable H 2 energy, freed from any dependence on fossil fuel.

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“…Various mechanisms exist for live cells to control osmotic pressure of the cytoplasm, such as the release or uptake of K + , which is attracted by the negative charges inside the cell (Gómez et al 2002). However, the cell membrane becomes more permeable when the cell ages, resulting in the decrease of the membrane potential (Bot and Prodan 2010). Ions (e.g., K + ) that are forced to concentrate inside of the viable cell by this potential should be able to diffuse back to the surrounding medium, but the concentration of such ions decreases as the cell ages, so the σ of bacteria suspended in buffer consequently decreases.…”

Section: Discussionmentioning

confidence: 99%

Complex Dielectric Properties of Sulfate-Reducing Bacteria Suspensions

Zhang

Slater

Prodan

2013

Geomicrobiology Journal

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Sulfate-reducing bacteria (SRB) can potentially enhance the remediation of heavy metals in the subsurface. Previous geophysical research has demonstrated the sensitivity of electrical measurements to SRB-mediated mineral transformation in porous media. However, the inherent dielectric properties of SRB and their direct contribution to the electrical properties of porous media are poorly understood. We studied the complex dielectric properties of SRB (Desulfovibrio vulgaris) suspensions at different concentrations and at different growth stages using a two-electrode dielectric spectroscopy measurement over the frequency range of 20 Hz to 1 MHz. Our results show higher dielectric responses (relative dielectric permittivity, real and imaginary conductivity) occurred with higher bacteria concentration at frequencies <10 kHz. Additionally, permittivity and conductivity both decreased as cells aged from mid-log phase to late stationary phase. Our results suggest that dielectric spectroscopy measurements can be used to noninvasively monitor biomass and various growth stages of SRB. Our work advances the interpretation of electrical signals associated with SRB observed in the subsurface.

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Quantifying the membrane potential during E. coli growth stages

Cited by 67 publications

References 32 publications

Selectivity mechanism of the mechanosensitive channel MscS revealed by probing channel subconducting states

Selectivity mechanism of the mechanosensitive channel MscS revealed by probing channel subconducting states

Bacterial formate hydrogenlyase complex

Complex Dielectric Properties of Sulfate-Reducing Bacteria Suspensions

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