title: Regulation of the cytotoxic effects of Pseudomonas fluorescens by growth temperature.
abstract: We had previously shown that the psychrotrophic bacterium Pseudomonas fluorescens can act as a pathogen, inducing apoptosis and necrosis in neurons and glial cells. In the present study, we investigated the influence of the growth temperature of P. fluorescens on its infectious potential. Adherence of P. fluorescens to glial cells was found to be maximal with bacteria grown at a low temperature (8 degrees C). At that temperature the swimming behaviour was markedly reduced. An increase in the growth temperature to 19, 28 or 32 degrees C strongly diminished the binding of bacteria to host cells. Thus, the adhesion phenotype of P. fluorescens appears to be independent of the motility of the bacteria. The apoptotic effect of P. fluorescens, determined by morphological (nuclear condensation) and biochemical (induction of nitric oxide synthase activity) indicators, correlated well with its binding activity on glial cells. In contrast, there was a clear dissociation between maximum binding and maximal necrotic action (measured by the release of lactate dehydrogenase) observed with bacteria grown at 19 degrees C. As suggested by capillary electrophoresis analysis, the differences in apoptotic effects may be related to variations in the molecular structure of LPS originating from bacteria grown at low and high temperatures, whereas the necrotic effect, which was maximal at the optimum temperature for the secretion of exoenzymes, could reflect variations in the metabolic activity of bacteria.
authors.affiliation: Laboratory of Cold Microbiology, UPRES2123, University of Rouen, 55, rue Saint Germain, 27000 Evreux, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Picot
authors.forename: Sana
authors.initials: S
authors.lastname: Mezghani-Abdelmoula
authors.forename: Sylvie
authors.initials: S
authors.lastname: Chevalier
authors.forename: Annabelle
authors.initials: A
authors.lastname: Merieau
authors.forename: Olivier
authors.initials: O
authors.lastname: Lesouhaitier
authors.forename: Josette
authors.initials: J
authors.lastname: Guerillon
authors.forename: Lionel
authors.initials: L
authors.lastname: Cazin
authors.forename: Nicole
authors.initials: N
authors.lastname: Orange
authors.forename: Marc G J
authors.initials: MG
authors.lastname: Feuilloley
mesh_terms: D000818:Animals; D017209:Apoptosis; D001422:Bacterial Adhesion; D018929:Cell Culture Techniques; D016923:Cell Death; D002467:Cell Nucleus / Q000648:ultrastructure; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008070:Lipopolysaccharides / Q000032:analysis; D009336:Necrosis; D009457:Neuroglia / Q000166:cytology* / Q000382:microbiology*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D011551:Pseudomonas fluorescens / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism / Q000472:pathogenicity*; D051381:Rats; D013696:Temperature
chemical_list: D008070:Lipopolysaccharides; D007770:L-Lactate Dehydrogenase; D019001:Nitric Oxide Synthase