English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

SUMMARY: The lipophilic cations butyltriphenylphosphonium (BTPP+), tetraphenylphosphonium (TPP+) and triphenylmethylphosphonium (TPMP+) were taken up into cells of Bacteroides amylophilus H18 under anaerobic conditions. Uptake was dependent on the presence of maltose together with both HCO-3 and Na+; it was at a maximum at concentrations of ≥ 20 mM-HCO-3 and ≤ 2 mM-Na+. The addition of 2-(n-heptyl)-hydroxyquinoline-N-oxide (HpHOQnO) or of an uncoupler of oxidative phosphorylation, or air, resulted in efflux of the lipophilic cations. From the binding behaviour and the physiological effects of the lipophilic cations, a membrane potential (δ ψ) of 140 mV was estimated. There was no detectable δpH at an external pH of 6.7. The cytoplasmic Na+concentration was estimated to be 0.2 mM, indicating that B. amylophilus can maintain a Na+concentration gradient equivalent to at least 150 mV. Variation in the external Na+concentration (2 to 180 mM) had little influence on δ ψ. High external concentrations of the fermentation products acetate, formate and succinate had little effect on the growth rate and the δ ψ. The cytoplasmic ATP concentration decreased rapidly on addition of HpHOQnO oxide or of an uncoupler. The maximum internal ATP concentration was only maintained at an external concentration≥2mM-Na+. The NADH: fumarate reductase activity of vesicles of B. amylophilus was associated with alkalization of the suspension medium. The amount of H+taken up was in excess of the expected amount of scalar H+and was partially sensitive to uncoupler. It is concluded that the δ ψ was generated via H+translocation driven primarily by the cytochrome-deficient NADH: fumarate reductase system. The transmembrane Na+gradient could be supported via the action of a Na+/2 H+antiporter.

The Membrane Potential in a Cytochrome-deficient Species of Bacteroides: Its Magnitude and Mode of Generation