This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kallas, T Articles by Castenholz, R W Search for Related Content PubMed PubMed Citation Articles by Kallas, T Articles by Castenholz, R W

 Previous Article  |  Next Article 

J Bacteriol. 1982 January; 149(1): 229-236

Internal pH and ATP-ADP pools in the cyanobacterium Synechococcus sp. during exposure to growth-inhibiting low pH.

ABSTRACT

Y-7c-s Synechococcus thermophilic strain grew at its maximum rate at pH 8 and above. The growth rate of this strain was inhibited at pH 7.0 and below, and at pH 6.0 there was no sustained growth. At a suboptimal pH, high light intensity further depressed the growth rate. The inhibition of growth resulted neither from pheophytinization nor from a low chlorophyll content. At pH 5.0 a loss of viability preceded the appearance of pheophytin. Cells exposed to low, growth-inhibiting external pH levels continued to maintain a high internal pH (pH 7.1 to 7.3, as determined at moderate light intensities by 31P nuclear magnetic resonance spectroscopy). Even during exposure to pH 4.8, cells retained a relatively high internal pH. Thus, it appeared that the inhibition of growth at low pH was not caused by acidification of the cytoplasm. Darkened cells maintained a slightly lower internal pH than irradiated cells. The ATP/(ATP + ADP) ratio decreased from 0.80 to 0.82 at pH 8.0 to about 0.6 when growth was limited by exposure to pH 6.0 or by low light intensity. It is possible, but not likely, that a limitation of the energy supply may slow or stop growth when the external pH is lowered.

This article has been cited by other articles:

• Ward, D. M., Ferris, M. J., Nold, S. C., Bateson, M. M. (1998). A Natural View of Microbial Biodiversity within Hot Spring Cyanobacterial Mat Communities. Microbiol. Mol. Biol. Rev. 62: 1353-1370 [Abstract] [Full Text]