The periplasm is the space between the inner and outer membrane in Gram-negative bacteria. In Gram-positive bacteria a smaller periplasmic space is found between the inner membrane and the peptidoglycan layer.

Where can periplasm be found?

The periplasm is a region in the cell wall of Gram-negative bacteria . It is located between the outer membrane and the inner, or cytoplasmic, membrane. Once considered to be empty space, the periplasm is now recognized as a specialized region of great importance.

Where is peptidoglycan found?

Peptidoglycan (murein) is an essential and specific component of the bacterial cell wall found on the outside of the cytoplasmic membrane of almost all bacteria (Rogers et al., 1980; Park, 1996; Nanninga, 1998; Mengin-Lecreulx & Lemaitre, 2005).