Efficiency of chitosans applied for flocculation of different bacteria.

Three types of well-characterized chitosans of different composition were applied to flocculate 8 different bacterial species. The aim of this study was to relate chitosan structure and flocculation characteristic to general bacterial characteristics such as the cell surface charge and hydrophobicity. Large differences in the flocculation efficiency of chitosan were found between different bacterial suspensions, both regarding the effective chitosan concentrations and the optimal type of chitosan. However, no correlation was observed between general surface characteristics of bacteria and flocculation by chitosan of different composition. It may be concluded that purely electrostatic interactions did not play a dominant role in flocculation of Gram-negative bacteria in this study. The presence of GlcNAc residues had clearly beneficial effects on flocculation in such cases.