Susceptibility of and resistance to organic acids

Various protein production changes are also known to be implicated in the development of resistance to acetic acid. One important protein that has been identified is now known as aconitase. It may also be possible that there exists some other mechanism, located in the bacterial cell membrane by which acetic acid resistance is conferred, as it is known that acetic acid causes toxicity by acting as an uncoupling agent, which would disturb the proton motive force. The presence of such a proton motive efflux system for acetic acid is present in A. acetii (Matsushita et al., 2005). 

however, unclear if it contributes to acetic acid resistance in acetic fermentation (Nakano, Fukaya, and Horinouchi, 2006). 

acetii a defect in the membrane-bound alcohol dehydrogenase has also been associated with a reduction in acetic acid resistance, implicating this enzyme in the development of resistance to this acid. It has also been found that resistance to acetic acid does not always result from resistance to low pH, as strains previously able to grow at a low pH cannot grow when the pH is decreased as a result of acetic acid (Nakano, Fukaya, and Horinouchi, 2006). 

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