E. coli has a cell wall, E. coli belongs to Gram-negative bacilli, Gram-negative and Gram-positive bacteria both have a cell wall, but the structure of the corresponding cell wall will be slightly different. Both of them contain peptidoglycan, but the number of peptidoglycan layers of Gram-positive bacteria can be more, up to 50 layers are possible. Gram-negative bacteria have fewer peptidoglycan layers, usually about 1-2 layers. The peptidoglycan can have a layer of lipoprotein outside, and the lipoprotein can connect the peptidoglycan and also the outer membrane outside. The outer membrane is actually the lipid bilayer, which is similar to the structure of the cell membrane, but is asymmetric, so it is also relatively different from the structure of the cell membrane. Outside the lipid bilayer is the lipopolysaccharide, which is the endotoxin of Gram-negative bacteria and can be divided into core polysaccharide, lipid A, and specific polysaccharide.