Variations in biofilm formation, desiccation resistance and Benzalkonium chloride susceptibility among Listeria monocytogenes strains isolated in Canada

Abstract

Listeria monocytogenes is a pathogenic foodborne microorganism noted for its ability to survive in the environment and food processing facilities. Survival may be related to the phenotype of individual strains including the ability to form biofilms and resist desiccation and/or sanitizer exposure. The objectives of this research were to compare 14 L. monocytogenes strains isolated from blood (3), food (6) and water (5) with respect to their benzalkonium chloride (BAC) sensitivity, desiccation resistance, and ability to form biofilm. Correlations were tested between those responses, and the presence of the SSI-1 (Stress Survival Islet) and LGI1/CC8 (Listeria Genomic Island 1 in a clonal complex 8 background) genetic markers. Genetic sequences from four strains representing different phenotypes were also probed for predicted amino acid differences in biofilm, desiccation, and membrane related genes. The water isolates were among the most desiccation susceptible strains, while strains exhibiting desiccation resistance harboured SSI-1 or both the SSI-1 and LGI1/CC8 markers. BAC resistance was greatest in planktonic LGI1/CC8 cells (relative to non-LGI1/CC8 cells), and higher BAC concentrations were also needed to inhibit the formation of biofilm by LGI1/CC8 strains during incubation for 48h and 6days compared to other strains. Formation of biofilm on stainless steel was not significantly (p>0.05) different among the strains. Analysis of genetic sequence data from desiccation and BAC sensitive (CP4 5-1, CP5 2-3, both from water), intermediate (Lm568, food) and desiccation and BAC resistant (08 5578, blood, human outbreak) strains led to the finding of amino acid differences in predicted functional protein domains in several biofilm, desiccation and peptidoglycan related genes (e.g., lmo0263, lmo0433, lmo0434, lmo0771, lmo0973, lmo1080, lmo1224, lmo1370, lmo1744, and lmo2558). Notably, the LGI1/CC8 strain 08-5578 had a frameshift mutation in lmo1370, a gene previously associated with desiccation resistance. In conclusion, the more desiccation and BAC resistant LGI1/CC8 isolates may pose a challenge for sanitation efforts.

Architecture and Viability of the Biofilms Formed by Nine Listeria Strains on Various Hydrophobic and Hydrophilic Materials

“…However, controversial results for the effects of cell surface hydrophobicity on biofilm formation on cell contact surfaces have been reported because biofilm formation depends on several factors [49], such as temperature. To this effect, it has been observed that biofilm formation is greater at temperatures above 20 • C than at refrigeration temperatures, for example 12 • C, the temperature used in this study [15,44,50,51].…”

“…Cells in biofilms become more resistant than planktonic cells to different environmental stress factors such as sanitizing agents, facilitating bacterial survival. Furthermore, biofilms can be a continuous source of contamination when in contact with foodstuffs, which can trigger human disease [15,16].…”

Initial Transcriptomic Response and Adaption of Listeria monocytogenes to Desiccation on Food Grade Stainless Steel

“…Also, there were no significant (p > 0.05) differences between the model parameters when the survival kinetics of the two strains were compared using the Weilbull model (Mafart et al, 2001) (data not shown). Lm 08-5578 has previously been shown to display increased desiccation tolerance compared to Lm 568 in desiccation trials at 23% RH and 15 • C (Piercey et al, 2017), indicating that Lm 08-5578 may have an advantage at a lower RH.…”

Prevalence, Potential Virulence, and Genetic Diversity of Listeria monocytogenes Isolates From Edible Mushrooms in Chinese Markets

“…Listeria monocytogenes is capable of surviving in various adverse environments, such as low temperature, high salinity, and a wide range of pH values ( Gandhi and Chikindas, 2007 ). In addition, L. monocytogenes biofilm exhibits a strong ability to resist disinfectants, resulting in persistent contamination of food plants ( nakamura et al, 2013 ; Piercey et al, 2017 ).…”