i) Acidophiles reverse the Dc to partially deflect the inward flow of protons. One potential mechanism of generating a reversed Dc is by potassium transport – a predominance of potassium-transporting ATPases is found in acidophile genomes.
(ii) Many acidophiles have evolved highly impermeable cell membranes to retard the influx of protons into the cell.
(iii) D pH is maintained through active proton export by transporters (blue). (iv) The sequencing of several acidophile genome sequences has indicated that there is a higher proportion of secondary transporters (green) than in neutralophiles. Overall, they reduce the energy demands associated with pumping necessary solutes and nutrients into the cell.
(v) The presence and availability of enzymes and/or chemicals capable of binding and sequestering protons might help to maintain pH homeostasis. (vi) Comparative genome analysis suggests that a larger proportion of DNA and protein repair systems might be present in acidophiles compared with neutralophiles and that this could be associated with the cellular demands of life at low pH. (
vii) Organic acids that function as uncouplers in acidophiles might be degraded by heterotrophic acidophiles.