Life in acid: pH homeostasis in acidophiles
Craig
Baker-Austin1 and Mark Dopson2
1Savannah River Ecology Laboratory, University of Georgia,
Drawer E, Aiken, SC 29802, USA
2Department of Molecular Biology, Umeå University, SE-901
87 Umeå, Sweden
Abstract
Microorganisms that have a pH optimum for growth of less than pH 3 are
termed ‘acidophiles’. To grow at low pH, acidophiles must maintain
a pH gradient of several pH units across the cellular membrane while producing
ATP by the influx of protons through the F0F1 ATPase.
Recent advances in the biochemical analysis of acidophiles coupled to
sequencing of several genomes have shed new insights into acidophile pH
homeostatic mechanisms. Acidophiles seem to share distinctive structural
and functional characteristics including a reversed membrane potential,
highly impermeable cell membranes and a predominance of secondary transporters.
Also, once protons enter the cytoplasm, methods are required to alleviate
effects of a lowered internal pH. This review highlights recent insights
regarding how acidophiles are able to survive and grow in these extreme
conditions.
SREL Reprint #3025
Baker-Austin, C. and M. Dopson. 2007. Life in acid: pH homeostasis in acidophiles. TRENDS in Microbiology 15(4):165-171.
