Coccal cell-wall compactness and the swelling action of denaturants

Isolated cell walls of Micrococcus lysodeikticus and Staphylococcus aureus were found to have relatively low densities in both the dried and hydrated states. Thus, it appears that the component polymers of these structures do not form crystallites or other highly condensed assemblies, but rather, that their distribution within the wall matrix is similar to that of the polymer chains in low-density, ion-exchange resins. Micrococcus lysodeikticus walls, which are composed mainly of peptidoglycan, swelled significantly when they were heated or transferred to 8 M urea solution. This finding suggests that the compactness of walls and their component peptidoglycans is determined in part by weak interactions that can be disrupted by urea or by heat.