Bacteria have strong architecture called cell wall as the outermost layer of cells. Each bacterium produces dozen of cell wall lytic enzymes with various functions. Especially cell wall lytic enzymes during vegetative growth phase play important roles in cell growth, cell separation, cell wall turnover, virulence etc. Since our group recently found a proteinaceous inhibitor that completely inhibits a group of cell wall lytic enzymes, we now investigate functions of the inhibitor.