Viability of E. coli after treatment with modified chitosan. Overnight incu-bated samples of variously modified chitosan with E. coli cells (initial amount2 × 107cells mL−1) were serially diluted and drop-seeded (A) on LB-agar or platedonto the agar medium, growing colonies counted and presented as the mean valueof CFU mL−1of three independent experiments (B).