I thought increasing proton concentration (lowering pH) would increase the proton motive force, but I'm reading that the opposite occurs. Trying to understand why increasing pH increases aminoglycoside penetration into bacteria.
The pmf consists of two gradients: an electrical potential (delta psi: ▵ψ), due to the charge separation across the membrane (positiveoutside/negativeinside) and a chemical transmembrane gradient of protons (delta pH: ▵pH, acidicoutside/alkalineinside).
pmf (mV)=delta psi+59×deltapH
As shown in the Fig. 3, when pHoutside decreases the pmf value increases due to the increase of delta pH value (detla pH=pHinside - pHoutside). The pHinside value is considered approximately 7.0.
For more information please refer to the following article.
https://jb.asm.org/content/178/11/3127.short
Thank you @Duried. This is what I suspected. So everything I read about aminoglycoside antibiotics indicates that they depend on the proton motive force for transport into bacteria, yet a higher pH enhances their transport. Perhaps they have an inverse dependence on the pmf?
Acid loving microbes are called acidophiles they prefer to go in acid medium. However there are many other E coliform bacteria prefer acid environment for growing.
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