RT Journal Article SR Electronic(1) A1 Corvini, P. F. X. A1 Gautier, H. A1 Rondags, E. A1 Vivier, H. A1 Goergen, J. L. A1 Germain, P. YR 2000 T1 Intracellular pH determination of pristinamycin-producing Streptomyces pristinaespiralis by image analysis JF Microbiology, VO 146 IS 10 SP 2671 OP 2678 DO https://doi.org/10.1099/00221287-146-10-2671 PB Microbiology Society, SN 1465-2080, AB Intracellular pH (pHi) is an essential parameter in the regulation of intracellular processes. Thus, its measurement might provide clues regarding the physiological state of cells cultivated in vitro. pHi of the filamentous, pristinamycin-producing Streptomyces pristinaespiralis was determined by epifluorescence microscopy and image analysis using the pH-sensitive fluorescent probe BCECF-AM [2’,7’-bis(2-carboxyethyl)-5(6)-carboxyfluorescein, acetoxymethyl ester]. Staining cell culture samples (OD660=1) of S. pristinaespiralis with 20 μM BCECF at 28 °C for 30 min yielded a green/red fluorescence ratio (R 527/600) that correlated with the pHi of the cells for values ranging from 6·5 to 8·5. When S. pristinaespiralis was cultivated in pristinamycin-producing conditions (in batch mode, with a constant external pH of 6·8), the measured pHi varied between 6·3 and 8·7. In fact, pHi correlated with the excretion of pristinamycins and glucose consumption during the production process., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-146-10-2671