Influence of temperature and pH on the biofilm formation by Listeria monocytogenes on the polypropylene surface

Aims: This study aimed to investigate the attachment and biofilm formation capabilities of Listeria monocytogenes on polypropylene surfaces under varying temperature (7 °C and 37 °C) and pH (6 and 7).The study also aimed to evaluate the cell surface characteristics, including electron donor/acceptor properties and hydrophobicity.Methodology and results: Listeria monocytogenes was cultivated in TSB broth for 168 h under static conditions.Biofilm quantification was carried out using a bead vortexing technique, while the microbial adhesion to solvent (MATS) assay was utilized to evaluate cell surface characteristics.Results indicated significantly greater attachment and biofilm formation at 37 °C compared to 7 °C.At 37 °C, biofilm production was initially higher at pH 7 during the first 3-24 h, but subsequently increased at pH 6 after 24 h.At 7 °C, biofilm formation was more prominent at pH 7 during early incubation but shifted to pH 6 after 168 h.Hydrophobicity of bacterial cells increased with higher temperature and lower pH, with electron-donating properties more pronounced at pH 6 and 37 °C.Conclusion, significance and impact of study: Temperature was identified as the major factor influencing biofilm formation.Suboptimal pH (pH 6) conditions enhanced biofilm production over time, while cell surface hydrophobicity likely contributed to the observed attachment patterns.This study highlights the persistence and adaptability of L. monocytogenes biofilms under food processing conditions, posing potential risks for cross-contamination.The findings emphasize the need for targeted sanitation protocols to address biofilm formation under varying environmental conditions.