par Gratia, Jean-Pierre 
Référence Colloids and surfaces. B, Biointerfaces, 2, 6, page (567-575)
Publication Publié, 1994-07
Référence Colloids and surfaces. B, Biointerfaces, 2, 6, page (567-575)
Publication Publié, 1994-07
Article révisé par les pairs
| Résumé : | Serratia marcescens, like several other bacterial species, is able to adhere to and swarm on growth surfaces, and this property is correlated with changes in the structures and functions of cells which pass from broth to solid media. In the case of the pigmented form of S. marcescens strain SMG40, the response to the contact with agar was influenced by the presence of Ca2+ ions as follows. (1) In the swimming phase, i.e. in soft 0.35% agar media, expansion was not modified upon the addition of 5-35 mM Ca2+ ions. (2) On growth surfaces inducing swarming, i.e. on media containing 0.75% agar (low agar), Ca2+ ions used at low concentrations (e.g. 0.5mM) enhanced both growth and expansion. (3) At higher concentrations (from 3 mM). the Ca2+ ions inhibited expansion but not growth. Correlatively, the cell density per unit of the surface occupied by bacteria inhibited from swarming was increased: expansion rates of swarms at successive periods were lower and showed less fluctuation than normal. In a non-pigmented but still good swarmer mutant, found to be more sensitive to calcium, expansion was reduced to 50% with at most 0.5 mM Ca2+ ions. One-step revenants recovered pigmentation and the initial response to Ca2+ ions described in points (2) and (3) above. The inhibitory activity of CaCl2 was partly antagonized by NaCl. Other properties implied in the interactions of Serratia cells with agar, i.e. pigmentation, adherence to solid surfaces and the production of an extracellular surfactant were not inhibited by Ca2+ ions. © 1994. |
