Figure 2

C − S conjugate was also effective against preformed biofilms built by other Gram-positive organisms.

Biofilms formed by Listeria innocua (A), Listeria welshimeri (B), Enterococcus faecalis (C) or Staphylococcus aureus (D) were exposed to 0.25 mg/mL C − S conjugate (23% streptomycin, ~13 kDa chitosan), equivalent chitosan (C) or streptomycin (S) alone and the respective mixture (C + S) for 24 h. Biofilms incubated in TSB containing phosphate-buffered saline were used as control. Biofilm mass and viable cells were quantified. Staphylococcus aureus biofilm architectures after 24 h treatment were further examined by scanning electron microscopy (E) and fluorescence microscopy (F). These experiments were performed twice with similar results each time. Error bars represent SD.