Kotyk A, Lapathitis G. Extracellular acidification by Saccharomyces cerevisiae in normal and in heavy water.
Folia Microbiol (Praha) 1998;
43:623-5. [PMID:
10069011 DOI:
10.1007/bf02816379]
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Abstract
Titratable acidity of the extracellular medium was compared with that calculated from pH changes in a suspension of Saccharomyces cerevisiae. After addition of cells to normal water the ratio of titratable acidity to the computed one was about 25, after addition of 50 mmol/L D-glucose it was about 13, after subsequent addition of K+ ions it was only 2. In heavy water the respective values were 30, 9, and 1. Apparently, the principal buffer-generating processes have to do with glucose metabolism but little with the K+/H+ exchange observed after addition of K+. D2O appears to block processes producing the buffering capacity of the medium, among them possibly extrusion of organic acids.
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