ISSN:
1432-0797
Source:
Springer Online Journal Archives 1860-2000
Topics:
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Abstract The effect of NH4Cl addition on intracellular pH (pH i ) was determined by flow cytometric measurements of the fluorescence of a pH-sensitive dye. The effects of NH4Cl on growth were determined for batch growth of cells in flasks in an incubator. The addition of NH4Cl caused a cytoplasmic acidification. A new lower steady-state value of pH i was attained within 20–40 min of NH4Cl addition. A correlation was found between the effects of NH4Cl on growth and on pH i : whereas 3 mM NH4Cl had little effect on growth and on pH i , 10 mM NH4Cl caused a substantial growth inhibition and a pH i decrease of 0.2–0.3 units. The effects of NH4Cl on growth and on pH i were found to be independent of the external pH value (pH e over the range 6.8 to 7.6, except that 10 mM NH4Cl was more toxic at pH e 7.6. The addition of NH4Cl caused an increase in the average cell volume at pH e 7.6, but had no effect on the average cell volume at pH e 's 6.8 and 7.2. For comparison, the effects of pH e alone on growth and on pH i were determined. There was little difference in cell growth at pH e 's 6.8, 7.2 and 7.6. At pH e 6.6, there was a substantial growth inhibition. Some measurements of the effects of pH e on pH i were made, although the steady-state value of pH i as a function of pH e was not determined due to limitations in the pH i -measuring technique. These measurements showed that pH i remained constant from pH e 7.6 to 6.8, but fell by 0.2 units at pH e 6.6, in agreement with the growth results.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00369278
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