The Bacterium's Way for Safe Enlargement and Division

The origin of the bacterial sacculus probably caused the origin of the domain Bacteria. Manufacture of this exoskeleton is complex because it involves the formation of polymerized peptidoglycan external to the cell membrane as a strong, stress-resistant sacculus. This process involves the formation of the disaccharide penta-muropeptide, its transport through the membrane, and its polymerization in the glycan and peptide directions to form an intact fabric covering the cell. Beyond that, the precursor must be inserted into the wall without risk of lysis and the wall must in some cases be safely turned over. These complex processes imply that in the time before the First Bacterium and in the time of the Last Universal Ancestor a set of diverse mechanisms arose and gave rise to variant mechanisms that functioned together to allow the formation of a strong covering for the bacterial cell.