Effects of benzalkonium chloride adaptation on controlling Listeria monocytogenes biofilms and its growth in food

Inthis study the eradication effectiveness offour commonly used disinfectants against benzalkonium chloride (BC) adapted and non-adapted biofilms of<i>Listeria monocytogenes </i>was compared and the effects offood preservatives onthe growth ofthese strains were comparatively evaluated onpasteurised chicken sausage. After BC adaptation, the minimum inhibitory concentrations (MICs) ofBC against planktonic bacteria of<i>L. monocytogenes</i> increased, while the MICs ofchlorine dioxide remained unchanged. BC adapted strains showed stronger biofilm formation than the wild-type parents. When used at1 MIC, the eradication rates ofchlorine dioxide onbiofilm biomass, cell viability and biofilm extracellular polymeric substance were higher than BC. When used atthe recommended concentrations, chlorine dioxide exhibited the highest efficiency inBC adapted and non-adapted biofilm eradication. Among the four food preservatives, nisin showed the highest inhibition ofboth BC adapted and non-adapted strains grown onpasteurised chicken sausage. Our data suggest that proper use ofBC isrequired toreduce the exposure of<i>L. monocytogenes</i> to sublethal concentrations of BC and the emergence of BC adapted strains.