Swarming Lag Sample Clauses

Swarming Lag. Following inoculation of vegetative cells onto an agar plate, a period of non- motile behavior is observed prior to swarmer cell differentiation. During lag phase, the initial population of cells divides and presumably undergoes physiological events necessary for swarming motility such as the inhibition of cell division, the continued extension of the cell body, and the expression of numerous flagella. Moreover, drastic biochemical rearrangements must occur within the colony to prevent dehydration and allow the colony to overcome surface tension so cells can migrate. The lag phase can be reduced by increasing the density of the starting culture, but a threshold is reached where the phenomenon no longer occurs, indicating nutrient depletion in the lag phase colony may contribute to the initiation of swarming (18, 107, 171). The time spent in lag phase can also be overcome by certain mutants (171, 202, 248, 253), reduced by exogenous addition of certain molecules (22, 23, 25, 254), and abolished if existing swarmer cells are transferred to a new agar plate (171, 255). Following swarmer cell differentiation at the colony periphery the overall population of cells becomes heterogeneous. Interestingly, the remaining immobile cells that do not differentiate are maintained throughout swarm colony development which has yet to be explained (18, 256).