Effect of batch and fed-batch growth modes on biofilm formation by Listeria monocytogenes at different temperatures.

The influence of Listeria monocytogenes (L. monocytogenes) biofilm formation feeding conditions (batch and fed-batch) at different temperatures on biofilm biomass and activity was determined. Biofilm biomass and cellular metabolic activity were assessed by Crystal Violet (CV) staining and 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt (XTT) colorimetric method, respectively. Live/Dead staining was also performed in order to get microscopic visualization of the different biofilms. Results revealed that at refrigeration temperature (4 degrees C) a higher amount of biofilm was produced when batch conditions were applied, while at higher temperatures the fed-batch feeding condition was the most effective on biofilm formation. Moreover, independently of the temperature used, biofilms formed under fed-batch conditions were metabolically more active than those formed in batch mode. In conclusion, this work shows that different growth modes significantly influence L. monocytogenes biofilm formation on abiotic surfaces as well as the metabolic activity of cells within biofilms.