Data from: eDNA-stimulated cell dispersion from Caulobacter crescentus biofilms upon oxygen limitation is dependent on a toxin-antitoxin system

In their natural environment, most bacteria preferentially live as complex
surface-attached multicellular colonies called biofilms. Biofilms begin
with a few cells adhering to a surface, where they multiply to form a
mature colony. When conditions deteriorate, cells can leave the biofilm.
This dispersion is thought to be an important process that modifies the
overall biofilm architecture and that promotes colonization of new
environments. In Caulobacter crescentus biofilms, extracellular DNA (eDNA)
is released upon cell death and prevents newborn cells from joining the
established biofilm. Thus, eDNA promotes the dispersal of newborn cells
and the subsequent colonization of new environments. These observations
suggest that eDNA is a cue for sensing detrimental environmental
conditions in the biofilm. Here we show that the toxin-antitoxin system
(TAS) ParDE4 stimulates cell death in areas of a biofilm with decreased O2
availability. In conditions where O2 availability is low, eDNA
concentration is correlated with cell death. Cell dispersal away from
biofilms is decreased when parDE4 is deleted, probably due to the lower
local eDNA concentration. Expression of parDE4 is positively regulated by
O2 and the expression of this operon is decreased in biofilms where O2
availability is low. Thus, a programmed cell death mechanism using an
O2-regulated TAS stimulates dispersal away from areas of a biofilm with
decreased O2 availability and favors colonization of a new, more
hospitable environment.