Antibacterial activity evaluation of quaternary chitin against Escherichia coli and Staphylococcus aureus

Water-soluble quaternary chitin/chitosan derivatives, O-[(2-hydroxy-3-trimethylammonium)propyl chitin (OHT-chitin), N-[(2-hydroxy-3-trimethylammonium)propyl chitosan (NHT-chitosan), and N,N,N-trimethylchitosan (TMC), having identical molecular weight and same anion, were prepared, and their antibacterial activities against Escherichia coli and Staphylococcus aureus were evaluated. Their minimum inhibitory concentration (MIC) values varied from 0.04 mg/mL to 20.48 mg/mL, and the minimum bactericidal concentration (MBC) values varied from 0.16 mg/mL to 40.96 mg/mL against E. coli and S. aureus, respectively. Transmission electron microscopy (TEM) clearly showed that there was serious damage on the bacterial walls, whereas there was some dissimilarity between TMC-treated E. coli and S. aureus.