title: Noninvasive measurement of bacterial intracellular pH on a single-cell level with green fluorescent protein and fluorescence ratio imaging microscopy.
abstract: 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.
authors.affiliation: Department of Veterinary Microbiology, The Royal Veterinary and Agricultural University, DK-1870 Frederiksberg C, Denmark.
authors.forename: Katja N
authors.initials: KN
authors.lastname: Olsen
authors.forename: Birgitte B
authors.initials: BB
authors.lastname: Budde
authors.forename: Henrik
authors.initials: H
authors.lastname: Siegumfeldt
authors.forename: K Björn
authors.initials: KB
authors.lastname: Rechinger
authors.forename: Mogens
authors.initials: M
authors.lastname: Jakobsen
authors.forename: Hanne
authors.initials: H
authors.lastname: Ingmer
mesh_terms: 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
chemical_list: D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins