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Proton gradient on cell membrane

About microscopic forms of life, including Bacteria, Archea, protozoans, algae and fungi. Topics relating to viruses, viroids and prions also belong here.

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Proton gradient on cell membrane

Postby EbseEbson » Sun Sep 12, 2010 4:12 pm

Hello!

I just read about ATP synthesis in bacteria, which use the proton gradient on the membrane to synthesize ATP. They establish this gradient by oxidizing nutrition, for example glucose. When doing this, protons are used up on the inner side of the membrane and other protons are transferred to the outer side of the membrane, establishing a gradient which can then be used to synthesize ATP by diffusion of the protons along the gradient through the membrane-bound ATP-synthase.

My question now is: If a bacteria is in an acidic environment, can it just use the protons in the medium to produce ATP? In this case it would just need an electron acceptor on the inner side of the membrane to keep the cellular pH neutral, for example by reducing O2 to H2O. I think in an acidic medium there should be enough protons, so there should be no need to artificially establish a gradient by using the electron transport chain, right?

I think I'm missing something here because it just sounds too easy. Additionally I read about Iron-oxidizing bacteria in acidic medium (pH 2). Could somebody please help me out?

Greets
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Postby JackBean » Mon Sep 27, 2010 8:14 am

yeah, they cannot much differentiate, whether is the gradiant "natural" or made by themselves ;) So, they just use protons, which they get. Some bacteria growing in enviroment with high salt content, known as halotrophs, used chloride ions instead ;)

Anyway, they need to use some kind of transporter, otherwise the ion would accumulate inside the cell ;)
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.
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