%0 Journal Article %A Corvini, P. F. X. %A Gautier, H. %A Rondags, E. %A Vivier, H. %A Goergen, J. L. %A Germain, P. %T Intracellular pH determination of pristinamycin-producing Streptomyces pristinaespiralis by image analysis %D 2000 %J Microbiology, %V 146 %N 10 %P 2671-2678 %@ 1465-2080 %R https://doi.org/10.1099/00221287-146-10-2671 %K BCECF-AM, 2’,7’-bis(2-carboxyethyl)-5(6)-carboxyfluorescein, acetoxymethyl ester %K intracellular pH %K Streptomyces pristinaespiralis %K epifluorescence microscopy %K R527/600, green/red fluorescence ratio (527/600 nm) %K pHi, intracellular pH %K image analysis %I Microbiology Society, %X 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. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-146-10-2671