Noninvasive measurement of bacterial intracellular pH on a single-cell level with green fluorescent protein and fluorescence ratio imaging microscopy.
We show that a pH-sensitive derivative of the green fluorescent protein, designated ratiometric GFP, can be used to measure intracellular pH (pHi) in both gram-positive and gram-negative bacterial cells. In cells expressing ratiometric GFP, the excitation ratio (fluorescence intensity at 410 and 430 nm) is correlated to the pHi, allowing fast and noninvasive determination of pHi that is ideally suited for direct analysis of individual bacterial cells present in complex environments.
Olsen
Katja N
KN
Department of Veterinary Microbiology, The Royal Veterinary and Agricultural University, DK-1870 Frederiksberg C, Denmark.
Budde
Birgitte B
BB
Siegumfeldt
Henrik
H
Rechinger
K Björn
KB
Jakobsen
Mogens
M
Ingmer
Hanne
H
D004926:Escherichia coli / Q000166:cytology* / Q000235:genetics / Q000502:physiology*; D049452:Green Fluorescent Proteins; D006863:Hydrogen-Ion Concentration; D013294:Lactococcus lactis / Q000166:cytology* / Q000235:genetics / Q000502:physiology*; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence
D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins