Chitosan kills Escherichia coli through damage to be of cell membrane mechanism

This paper aims to identify the interaction of chitosan (CTS) with bacterial membrane and delineate the inhibition mechanism of CTS towards Gram-negative bacteria. The inhibition activity of CTS against Escherichia coli (E coli) was evaluated by measuring O.D(610nm). CTS have increased the permeabilities of the outer membrane (OM) and inner membrane (IM) of E. coli, and ultimately disrupted the cell membrane with the release of cellular contents. Morphologies of bacteria treated with CTS were observed by Transmission electron microscopy (TEM), which indicated that it was the primary inhibition action for CTS to damage the bacterial cell membranes. The interaction between CTS and a model phospholipids membrane was studied, and the precipitates formed with CTS and phosphatidylcholine (PC) suggested the damage of bacterial cell membranes was likely to be caused by the electrostatic interaction between -NH(3)(+) groups of CTS and carbonyl and phosphoryl groups of the phospholipid components of the cell membrane. (C) 2009 Published by Elsevier Ltd.