Possible Rethink of the Bacterial Peptidoglycan Layer as a Non-Porous Layer Rather Than a Perforated Mesh

In Gram-negative bacteria, the peptidoglycan layer is often thought to be a thin layer (even monolayer) that is in-between the two phospholipid bilayer of the bacterial double membrane cell envelope. However, preliminary evidence from scanning electron microscopy observations of the shape and morphology of Escherichia coli DH5α cells subjected to autoclave treatment at 121 oC for 20 minutes suggests that the peptidoglycan layer may be thicker, and it may be a non-porous layer rather than a perforated mesh. Specifically, the traditional view of the E. coli peptidoglycan layer as a thin or monolayer layer punctuated with ion channels and transporter does not explain the ability of E. coli cells to retain its cellular structure after autoclave treatment. On the other hand, the new proposed model of a thicker peptidoglycan layer which is non-porous may help explain the observation of intact E. coli cells (without any holes) after autoclave treatment. Future work may examine the compressive and tensile strength of E. coli cells both before and after autoclave treatment to gain a deeper understanding of its mechanical properties as well as draw inference on the structure of the peptidoglycan layer.