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Séminaire d’Adrian Daerr

Bacillus subtilis on a gel surface : from mass swarming to colony sliding


Adrian Daerr Laboratoire Matière et Systèmes Complexes Université Paris Diderot

Bacillus subtilis on a gel surface : from mass swarming to colony sliding

Bacillus subtilis forms dendric colonies on gel surfaces through the collective motion of groups of 10^4 to 10^5 cells which form the compact tips of elongating dendrites (cf image). We investigate some physical aspects of this phenomenon, for which humidity and the surfactant production by the bacteria plays as much of a role as does the motility of the hyperflagellated swarmer cells. Observations at different spatial and temporal scales suggest that the bacteria initiate mass swarming by actively depinning the colony border. This hypothesis is nicely illustrated by a novel mode of locomotion, tentatively termed "mass sliding" or "colony sliding", which we discovered with a modified experimental protocol.