title: Rapid assessment of the physiological status of Streptococcus macedonicus by flow cytometry and fluorescence probes.
abstract: Flow cytometry in combination with fluorescence probes was applied to rapidly assess the physiological status of Streptococcus macedonicus ACA-DC 198, a newly described member of the lactic acid bacteria group with technologically important features (e.g. lantibiotic production). A sonication procedure was developed for disaggregating typical streptococci chains in order to optimize cell preparations for single cell analysis. Single stained live and dead populations of S. macedonicus cells were clearly resolved based on membrane potential by bis-oxonol [DiBAC(4)(3)], membrane integrity by Propidium Iodide (PI) and enzymatic activity as well as membrane integrity by Carboxyfluorescein Diacetate (cFDA). Further, estimation of both live and dead cells by a cFDA/PI two-colour flow cytometric assay showed excellent correlation with the dead cells in the samples (dead(FCM)=0.9945 dead(S)-0.806, R(2)=0.9986 and live(FCM)=-0.978 dead(S)+98.895, R(2)=0.9992). Finally, the assay was applied to study the physiology of S. macedonicus after acid stress. Interestingly, in situ assessment of the physiological status of stressed S. macedonicus cells by flow cytometry and single cell sorting revealed the coexistence of three distinct subpopulations according to their fluorescence labelling behaviour and culturability, representing intact/culturable, permeabilized/dead and potentially injured cells with the latter exhibiting both metabolic activity and membrane permeabilization as well as decreased culturability.
authors.affiliation: Laboratory of Dairy Research, Department of Food Science and Technology, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Papadimitriou
authors.forename: Harris
authors.initials: H
authors.lastname: Pratsinis
authors.forename: Gerhard
authors.initials: G
authors.lastname: Nebe-von-Caron
authors.forename: Dimitris
authors.initials: D
authors.lastname: Kletsas
authors.forename: Effie
authors.initials: E
authors.lastname: Tsakalidou
mesh_terms: D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology*; D002470:Cell Survival; D004396:Coloring Agents / Q000378:metabolism; D005434:Flow Cytometry / Q000379:methods*; D005452:Fluoresceins / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D011419:Propidium / Q000378:metabolism; D013291:Streptococcus / Q000254:growth & development / Q000502:physiology; D013858:Thiobarbiturates / Q000378:metabolism; D013997:Time Factors
chemical_list: D004396:Coloring Agents; D005452:Fluoresceins; D005456:Fluorescent Dyes; D013858:Thiobarbiturates; C027780:carboxyfluoresceindiacetate; D011419:Propidium; C025284:bis(1,3-diethylthiobarbiturate)trimethineoxonol