Diversity of Firmicutes peptidoglycan hydrolases and specificities of those involved in daughter cell separation.

Within Streptococcus thermophilus, Cse was identified as the major cell disconnecting peptidoglycan hydrolase (PGH) and was demonstrated to be species-specific. To identify cell disconnecting PGHs encoded by other Streptococcus genomes, we explored the diversity of domains carried by Firmicutes PGHs, and especially that of enzymes involved in daughter cell separation. This work brings to light the diversity of PGHs and reveals that each species recruits its own cell-separating enzyme distinct from that of the others. This specificity is probably correlated with the diversity of substrates found in the bacterial cell wall.