MEASUREMENT OF CYTOPLASMIC PH OF THE ALKALIPHILE BACILLUS-LENTUS C-125 WITH A FLUORESCENT PH PROBE

A method was established to measure the cytoplasmic ph of the facultat ive alkaliphilic strain, Bacillus lentus C-125. The bacterium was load ed with a ph-sensitive fluorescent probe, 2',7'-bis-(2-carboxyethyl)-5 (and -6)-carboxyfluorescein (BCECF), and cytoplasmic ph was determine d from the intensity of fluorescence of the intracellular BCECF. The a ctivity of the organism to maintain neutral cytoplasmic pH was assesse d by measuring the cytoplasmic ph of the cells exposed to various ph c onditions. The cytoplasmic ph maintenance activity of C-125 increased with increasing culture ph. indicating that the activity was regulated in response to the culture ph.