In this issue of the Journal of Bacteriology, J.-S. Bourassa, G. Jeannotte, S. Lebel-Beaucage, and P. B. Beauregard (J Bacteriol 204:e00181-22, 2022, https://doi.org/10.1128/jb.00181-22) showed that ICEBs1 propagation in Bacillus subtilis biofilm relies almost exclusively on transconjugants. It appears restricted to clusters of bacteria in a close neighborhood of initial donor cells, which are heterogeneously distributed in the biofilm and expand vertically toward the air-liquid interface.
Keywords: biofilms; conjugation; integrative conjugative elements; single cell.