In order for bacteria to divide by binary fission and increase their size following division, links in the peptidoglycan must be broken, new peptidoglycan monomers must be inserted, and the peptide cross links must be resealed.
A group of bacterial enzymes called autolysins break the glycosidic bonds between the peptidoglycan monomers at the point of growth along the existing peptidoglycan. They also break the peptide cross-bridges that link the rows of sugars together. In this way, new peptidoglycan monomers can be inserted and enable bacterial growth.