Behavior of Listeria monocytogenes in a Pseudomonas putida Biofilm on a Condensate-Forming Surface

Abstract

Listeria monocytogenes has been isolated from condensate-forming surfaces in food processing plants. The objective of this research was to observe the behavior of L. monocytogenes on condensate-covered stainless steel with a Pseudomonas putida biofilm. L. monocytogenes-containing biofilms, either with or without added chicken protein, were incubated in a high humidity chamber at 12 degrees C to allow formation of condensate. Samples were analyzed for attached and unattached L. monocytogenes and total plate count periodically for 35 days. Samples were also taken for microscopic observation of Listeria and bacterial extracellular polymeric substances (EPS). L. monocytogenes attached in significantly greater numbers (> 3-log difference) to surfaces with preexisting P. putida biofilms than to Pseudomonas-free surfaces. L. monocytogenes survived in the presence or absence of P. putida with no added nutrients for 35 days, with numbers of survivors in the range of 3 to 4 log CFU/cm2 in the presence of P. putida and less than 2.9 log CFU/cm2 in pure culture. Attached and unattached L. monocytogenes were at similar levels throughout the incubation under all conditions studied. The addition of protein to the biofilms allowed growth of L. monocytogenes in pure culture during the first 7 days of incubation. Numbers of L. monocytogenes were not affected by the presence of P. putida when protein was present. Unattached L. monocytogenes were at levels of 3.6 to 6.7 log CFU/cm2 on the protein-containing surfaces. Microscopic observation of the condensate-covered biofilms indicated that L. monocytogenes formed microcolonies embedded within an EPS matrix over a 28-day period. This research demonstrates that L. monocytogenes can survive on condensate-forming stainless steel in low and high nutrient conditions, with or without the presence of Pseudomonas biofilm. The Listeria can detach and, therefore, have the potential to contaminate product.

Differential Biofilm Formation and Chemical Disinfection Resistance of Sessile Cells of Listeria monocytogenes Strains under Monospecies and Dual-Species (with Salmonella enterica) Conditions

“…Evidently, bacterial pathogens, such as L. monocytogenes and S. enterica, can be entrapped in multispecies sessile communities formed on such surfaces. In addition, attachment and biofilm formation by these two species have been shown to be influenced by either the natural in situ presence of other species or just their metabolic by-products (8,10,11,24,26,27,29,32,33,37,38,39,46,58,77). For instance, the presence of Staphylococcus xylosus and Pseudomonas fragi affected the numbers of L. monocytogenes biofilm cells on stainless steel (51), while compounds present in Hafnia alvei cell-free culture supernatant inhibited the early stage of S. enterica serovar Enteritidis biofilm formation on the same material (10).…”

Culture Conditions of Roseobacter Strain 27-4 Affect Its Attachment and Biofilm Formation as Quantified by Real-Time PCR

“…Bacteria may interact during attachment and in biofilms (3,7,11), and antagonistic interactions during attachment have been observed with bacteria belonging to the Roseobacter clade (20). The primers designed for Roseobacter strain 27-4 did not (5), and the DNA of dead bacteria must therefore be removed or bound to ethidium monoazide (21) before the procedure is used in systems where there is interaction between bacteria.…”

Coaggregation between Rhodococcus and Acinetobacter strains isolated from the food industry

“…Acinetobacter calcoaceticus has been shown to promote biofilm formation by the pathogenic bacteria Escherichia coli O157:H7, however the mechanisms involved were not investigated (Habimana et al 2010). Also the food borne pathogenic bacterium Listeria monocytogenes is a relatively poor biofilm former , which adhesion and biofilm formation may be induced in multispecies biofilms (Bremer et al 2001;Hassan et al 2004). Given the available literature it is likely that species of Acinetobacter and Rhodococcus may promote biofilm recruitment of each other and other species including pathogenic bacteria and this could be in part due to coaggregation interactions.…”