title: A Preliminary Study of the Effects of pH upon Fluorescence in Suspensions of Prevotella intermedia.
abstract: The quantification of fluorescence in dental plaque is currently being developed as a diagnostic tool to help inform and improve oral health. The oral anaerobe Prevotella intermedia exhibits red fluorescence due to the accumulation of porphyrins. pH affects the fluorescence of abiotic preparations of porphyrins caused by changes in speciation between monomers, higher aggregates and dimers, but this phenomenon has not been demonstrated in bacteria. Fluorescence spectra were obtained from suspensions of P. intermedia that were adjusted to pHs commensurate with the range found within dental plaque. Two fluorescent motifs were identified; 410 nm excitation / 634 nm emission (peak A) and 398 nm excitation / 622 nm emission (peak B). A transition in the fluorescence spectra was observed from peak A to peak B with increasing pH which was also evident as culture age increased from 24 hours to 96 hours. In addition to these 'blue-shifts', the intensity of peak A increased with pH whilst decreasing with culture age from 24 to 96 hours. A bacterium's relationship with the local physiochemical environment at the time of image capture may therefore affect the quantification of dental plaque fluorescence.
authors.affiliation: Department of Health Services Research, University of Liverpool, Liverpool, United Kingdom.|School of Dentistry, University of Liverpool, Liverpool, United Kingdom.
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Hope
authors.affiliation: Department of Health Services Research, University of Liverpool, Liverpool, United Kingdom.|Department of Medical Microbiology, Royal Liverpool and Broadgreen University Hospital, Liverpool, United Kingdom.
authors.forename: Karen
authors.initials: K
authors.lastname: Billingsley
authors.affiliation: Department of Health Services Research, University of Liverpool, Liverpool, United Kingdom.|Inspektor Research Systems BV, Amsterdam, The Netherlands.
authors.forename: Elbert
authors.initials: E
authors.lastname: de Josselin de Jong
authors.affiliation: Department of Health Services Research, University of Liverpool, Liverpool, United Kingdom.|School of Dentistry, University of Liverpool, Liverpool, United Kingdom.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Higham
mesh_terms: D005453:Fluorescence; D006863:Hydrogen-Ion Concentration; D018713:Prevotella intermedia / Q000254:growth & development / Q000378:metabolism*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013997:Time Factors