title: Variability of Listeria monocytogenes strains in biofilm formation on stainless steel and polystyrene materials and resistance to peracetic acid and quaternary ammonium compounds.
abstract: Listeria monocytogenes is a foodborne pathogen able to tolerate adverse conditions by forming biofilms or by deploying stress resistant mechanisms, and thus manages to survive for long periods in food processing plants. This study sought to investigate the correlation between biofilm forming ability, tolerance to disinfectants and cell surface characteristics of twelve L. monocytogenes strains. The following attributes were evaluated: (i) biofilm formation by crystal violet staining method on polystyrene, and by standard cell enumeration on stainless steel and polystyrene; (ii) hydrophobicity assay using solvents; (iii) minimum inhibitory concentration (MIC) and biofilm eradication concentration (BEC) of peracetic acid (PAA) and quaternary ammonium compounds (QACs), and (iv) resistance to sanitizers (PAA 2000ppm; QACs 500ppm) of biofilms on polystyrene and stainless steel. After 72h of incubation, higher biofilm levels were formed in TSB at 20°C, followed by TSB at 37°C (P=0.087) and diluted TSB 1/10 at both 20 (P=0.005) and 37°C (P=0.004). Cells grown at 30°C to the stationary phase had significant electron donating nature and a low hydrophobicity, while no significant correlation of cell surface properties to biofilm formation was observed. Strains differed in MICPAAand BECPAAby 24- and 15-fold, respectively, while a positive correlation between MICPAAand BECPAAwas observed (P=0.02). The MICQACswas positively correlated with the biofilm-forming ability on stainless steel (P=0.03). Regarding the impact of surface type, higher biofilm populations were enumerated on polystyrene than on stainless steel, which were also more tolerant to disinfectants. Among all strains, the greatest biofilm producer was a persistent strain with significant tolerance to QACs. These results may contribute to better understanding of L. monocytogenes behavior and survival on food processing surfaces.
authors: Laboratory of Food Quality and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece; Laboratory of Food Microbiology and Biotechnology, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece.
authors: Sofia V
authors: SV
authors: Poimenidou
authors: Laboratory of Food Quality and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece.
authors: Marilena
authors: M
authors: Chrysadakou
authors: Laboratory of Food Quality and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece.
authors: Aikaterini
authors: A
authors: Tzakoniati
authors: Laboratory of Food Quality and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece.
authors: Vasiliki C
authors: VC
authors: Bikouli
authors: Laboratory of Food Microbiology and Biotechnology, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece.
authors: George-John
authors: GJ
authors: Nychas
authors: Laboratory of Food Quality and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece. Electronic address: pskan@aua.gr.
authors: Panagiotis N
authors: PN
authors: Skandamis
mesh_terms: D001422:Bacterial Adhesion / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects*; D015169:Colony Count, Microbial; D004202:Disinfectants / Q000737:chemistry / Q000494:pharmacology; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D057927:Hydrophobic and Hydrophilic Interactions; D008089:Listeria monocytogenes / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D010463:Peracetic Acid / Q000737:chemistry* / Q000494:pharmacology; D011137:Polystyrenes / Q000737:chemistry*; D025341:Principal Component Analysis; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D013193:Stainless Steel; D013696:Temperature
chemical_list: D004202:Disinfectants; D011137:Polystyrenes; D000644:Quaternary Ammonium Compounds; D013193:Stainless Steel; D010463:Peracetic Acid
keywords: Abiotic surfaces; BEC; Disinfectants; Hydrophobicity; MIC