Dynamics of Biofilm Formation by Salmonella Typhimurium and Beef Processing Plant Bacteria in Mono- and Dual-Species Cultures

Citation

Visvalingam, J., Zhang, P., Ells, T.C., Yang, X. (2019). Dynamics of Biofilm Formation by Salmonella Typhimurium and Beef Processing Plant Bacteria in Mono- and Dual-Species Cultures. Microbial Ecology, [online] 78(2), 375-387. http://dx.doi.org/10.1007/s00248-018-1304-z

Plain language summary

Biofilms are difficult to clean and can cause repeated contamination of meat products. The formation of biofilms can be affected by many factors including background microflora. This study aimed to determine the impact of bacteria from a beef plant conveyor belt on the biofilm formation of Salmonella in dual-species cultures. Beef plant isolates including Gram-negative aerobes (GNA), Gram-positive aerobes (GPA), lactic acid bacteria (LAB), Enterobacteriaceae (EB), and generic Escherichia coli (GEC) were included for developing biofilms in mono- and co-culture with S. Typhimurium. Five selected cultures in planktonic form and in biofilms were tested for susceptibility to two commonly used sanitizers. Most mono-cultures, but all co-culture pairings with S. Typhimurium formed biofilms. The predominant effect of EB and only effect of GEC strains on the biofilm formation of S. Typhimurium was antagonistic, while that of GPA was synergistic. The effect was highly variable for the GNA isolates. Six aerobic isolates that formed moderate/strong biofilms by day 2 greatly boosted the co-culture biofilm formation. Seven Gram-negative bacteria were antagonistic against the biofilm formation of the co-cultures. Both sanitizers completely inactivated the selected planktonic cultures, but were largely ineffective against biofilms. In conclusion, all beef plant isolates assessed formed biofilms when paired with S. Typhimurium. The findings provide evidence for developing biocontrol and effective sanitization strategy for controlling biofilms.

Abstract

This study aimed to determine the impact of bacteria from a beef plant conveyor belt on the biofilm formation of Salmonella in dual-species cultures. Beef plant isolates (50) including 18 Gram-negative aerobes (GNA), 8 Gram-positive aerobes (GPA), 5 lactic acid bacteria (LAB), 9 Enterobacteriaceae (EB), and 10 generic Escherichia coli (GEC) were included for developing biofilms in mono- and co-culture with S. Typhimurium at 15 °C for 6 days. Five selected cultures in planktonic form and in biofilms were tested for susceptibility to two commonly used sanitizers (i.e. E-San and Perox-E Plus). In mono-cultures, ≥ 80, 67, 61, 20, and 13% of GEC, EB, GNA, LAB, and GPA, respectively, developed measurable biofilms after 2 days, while all co-culture pairings with S. Typhimurium achieved some level of biofilm production. The predominant effect of EB and only effect of GEC strains on the biofilm formation of S. Typhimurium was antagonistic, while that of Gram-positive bacteria was synergistic, with the effect being more prominent on day 6. The effect was highly variable for the GNA isolates. Six aerobic isolates that formed moderate/strong biofilms by day 2 greatly boosted the co-culture biofilm formation. Seven Gram-negative bacteria were antagonistic against the biofilm formation of the co-cultures. Both sanitizers completely inactivated the selected planktonic cultures, but were largely ineffective against biofilms. In conclusion, all beef plant isolates assessed formed biofilms when paired with S. Typhimurium. Aerobic biofilm formers may create a more favorable condition for Salmonella biofilm formation, while some beef plant isolates have potential as a biocontrol strategy for Salmonella biofilms.

Publication date

2019-08-15

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