Abstract:
Listeria monocytogenes forms biofilms on food contact surfaces, a niche from where it
dislodges to contaminate food products including fresh produce. Probiotics and their derivatives
are considered promising alternative strategies to curb the presence of L. monocytogenes in varied
food applications. Nonetheless, studies on their anti-biofilm effects against L. monocytogenes from
avocados and cucumbers are sparse. This study screened the biofilm formation capabilities of
L. monocytogenes strains Avo and Cuc isolated from the avocado and cucumber fruits respectively, and
strain 243 isolated from an avocado processing plant; and evaluated the anti-biofilm effects of cell
free supernatants (CFS) of Lactobacillus acidophilus La14 150B, Lactiplantibacillus plantarum B411 and
Lacticaseibacillus rhamnosus ATCC 53103 against their biofilms formed on polyvinyl chloride (PVC)
and stainless steel. All the L. monocytogenes strains formed biofilms (classified either as moderate
or strong biofilm formers) on these materials. The presence of CFS reduced the biofilm formation
capabilities of these strains and disrupted the integrity of their pre-formed biofilms. Quantitative
reverse transcriptase polymerase chain reaction revealed significant reduction of positive regulatory
factor A (prfA) gene expression by L. monocytogenes biofilm cells in the presence of CFS (p < 0.05).
Thus, these CFS have potential as food grade sanitizers for control of L. monocytogenes biofilms in the
avocado and cucumber processing facilities.
