Polyethyleneimine (PEI), a polycationic polymer substance used in various bioprocesses as a flocculating agent and to immobilize enzymes, was recently shown to make Gram-negative bacteria permeable to hydrophobic antibiotics and to detergents. Because this suggests impairment of the protective function of the outer membrane (OM), the effect of PEI on the ultrastructure of was investigated. Massive alterations in the OM of PEI-treated and thin-sectioned bacteria were observed by electron microscopy. Vesicular structures were seen on the surface of the OM, but no liberation of the membrane or its fragments was evident. Since a potential mechanism for the action of PEI could be its binding to anionic LPSs on the OM surface, the interaction of PEI with isolated LPSs was assayed The solubility of smooth-type LPSs of , regardless of the sugar composition of their O-specific chains, was not affected by PEI, nor was that of Ra-LPS (lacking O-specific chains but having a complete core oligosaccharide). PEI strongly decreased the solubility of rough-type LPSs of the chemotypes Rb2 and Re, whereas it had only a weak effect on the abnormally cationic Rb2-type mutant LPS, suggesting that the negative charge to mass ratio of LPS plays a critical role in the interaction.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error