The Mechanism of Onset of the Stationary Phase in Euglena gracilis Grown with 10 mM Succinate: Intracellular pH Values*
The Mechanism of Onset of the Stationary Phase in Euglena gracilis Grown with 10 mM Succinate: Intracellular pH Values*
复制标题
在 10 mM 琥珀酸盐下生长的眼虫中静止期的开始机制：细胞内 pH 值*
DOI：
10.1111/j.1550-7408.1971.tb03301.x
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发表时间：
1971
影响因子：
2.2
通讯作者：
B. Levedahl
中科院分区：
文献类型：
--
作者：
J. Votta;T. Jahn;B. Levedahl
SYNOPSIS. When Euglena gracilis were grown with 10mM succinate at pH 3.5 the extracellular pH averaged 3.62 and the cultures had produced 6 × 105 cells/ml when the stationary phase began. Oxygen consumption values reached a maximum of 30 μliters/106 cells/hr. Total protein and dry weights per cell remained constant during the logarithmic phase and began to decline when the late logarithmic phase was reached. Added succinate caused the cultures in stationary phase to commence logarithmic growth once more. Onset of the stationary phase in cultures grown at pH 3.5 was due to depletion of succinate.
When cultures were grown at pH 6.9 the extracellular pH averaged 7.62 and the cultures produced 3 × 105 cells/ml when the stationary phase began. Oxygen consumption values reached a maximum of 20 μliters/106 cells/hr during the logarithmic phase. The decline in total protein and dry weights per cell began at the beginning of the logarithmic phase and continued into the stationary phase of growth. Cultures grown at pH 3.5 should produce a larger number of cells/ml than cultures grown at pH 6.9 if the cells are responding to the unionized moiety of succinate and not the ionized moiety. At pH 3.5 83% of the succinate is unionized, whereas at pH 6.9 0.20% of the succinate is unionized. The onset of the stationary phase in cultures grown at pH 3.5 and pH 6.9 is due to lack of an adequate amount of extracellular unionized succinate.
Intracellular pH values were determined in cultures grown at pH 6.9 using the weak acid DMO (5.5-dimethyl-2,4-oxazolidinedione). As the extracellular pH increased from 6.90 to 7.62, the intracellular pH increased from 5.89 to 6.89. As the extracellular pH increased from 7.62 to 8.44, the intracellular pH increased from 6.89 to 7.50.
