Action of chitosan, nisin and sodium lactate on the inhibition and cell membrane damage of Listeria innocua and Shewanella putrefaciens

LAURA I SCHELEGUEDA; MARÍA F GLIEMMO; CARMEN A. CAMPOS

Lisboa

Conferencia; II International Conference on Antimicrobial Research; 2012

Formatex Research Center

The effect of chitosan, nisin, sodium lactate and binary combinations of chitosan with nisin or sodium lactate on the growth of Listeria innocua and Shewanella putrefaciens was study. Their mode of action through the evaluation of cell surface damage was also investigated. Minimal inhibitory concentrations, antimicrobial interactions, cell constituents´ release and cell hydrophobicity were determinated. Although studied antimicrobials were able to inhibit the growth of L. innocua and S. putrefaciens, their mode of action may be different according to the structural characteristics of the microorganisms. L. innocua, was sensitive to nisin, and the action of the mentioned antimicrobial on the cell membrane was evident when the cell constituents’ release was evaluated. Regarding to chitosan, it also seems to act on the cell surface, but in a smaller magnitude than nisin, since cell constituents’ were not release but hydrophobicity was increase. Sodium lactate would pass the cell membrane and acts in the cytoplasm. When it comes to S. putrefaciens, nisin and sodium lactate would be able to disrupt the outer membrane, while chitosan may cause the inhibition through other mechanisms, or higher concentrations would be necessary to detect its action.