title: Assessment of the dynamics of the physiological states of Lactococcus lactis ssp. cremoris SK11 during growth by flow cytometry.
abstract: OBJECTIVE
  The aim of this study was to improve knowledge about the dynamics of the physiological states of Lactococcus lactis ssp. cremoris SK11, a chain-forming bacterium, during growth, and to evaluate whether flow cytometry (FCM) combined with fluorescent probes can assess these different physiological states.
  
  
  RESULTS
  Cellular viability was assessed using double labelling with carboxyfluorescein diacetate and propidium iodide. FCM makes it possible to discriminate between three cell populations: viable cells, dead cells and cells in an intermediate physiological state. During exponential and stationary phases, the cells in the intermediate physiological state were culturable, whereas this population was no longer culturable at the end of the stationary phase.
  We introduced a new parameter, the ratio of the means of the fluorescence cytometric index to discriminate between viable culturable and viable nonculturable cells. Finally, this work confirms the relevance of FCM combined with two fluorescent stains to evaluate the physiological states of L. lactis SK11 cells during their growth and to distinguish viable cells from viable but not culturable cells.
authors.affiliation: AgroParisTech, INRA, UMR 782 Génie et Microbiologie des Procédés Alimentaires, Thiverval-Grignon, France.
authors.forename: A
authors.initials: A
authors.lastname: El Arbi
authors.forename: S
authors.initials: S
authors.lastname: Ghorbal
authors.forename: A
authors.initials: A
authors.lastname: Delacroix-Buchet
authors.forename: M
authors.initials: M
authors.lastname: Bouix
mesh_terms: D015169:Colony Count, Microbial; D005434:Flow Cytometry / Q000379:methods*; D005452:Fluoresceins; D005456:Fluorescent Dyes; D013294:Lactococcus lactis / Q000254:growth & development / Q000502:physiology*; D050296:Microbial Viability; D011419:Propidium; D013194:Staining and Labeling / Q000379:methods
chemical_list: D005452:Fluoresceins; D005456:Fluorescent Dyes; C027780:carboxyfluoresceindiacetate; D011419:Propidium