Conditions of In Vitro Biofilm Formation by Serogroups of Listeria monocytogenes Isolated from Hass Avocados Sold at Markets in Mexico

Abstract

Listeria monocytogenes is an important pathogen that has been implicated in foodborne illnesses and the recall of products such as fruit and vegetables. This study determines the prevalence of virulence-associated genes and serogroups and evaluates the effects of different growth media and environmental conditions on biofilm formation by L. monocytogenes. Eighteen L. monocytogenes isolates from Hass avocados sold at markets in Guadalajara, Mexico, were characterized by virulence-associated genes and serogroup detection with PCR. All isolates harbored 88.8% actA, 88.8% plcA, 83.3% mpl, 77.7% inlB, 77.7% hly, 66.6% prfA, 55.5% plcB, and 33.3% inlA. The results showed that 38.8% of isolates harbored virulence genes belonging to Listeria pathogenicity island 1 (LIPI-1). PCR revealed that the most prevalent serogroup was serogroup III (1/2b, 3b, and 7 (n = 18, 66.65%)), followed by serogroup IV (4b, 4d–4e (n = 5, 27.7%)) and serogroup I (1/2a–3a (n = 1, 5.5%)). The assessment of the ability to develop biofilms using a crystal violet staining method revealed that L. monocytogenes responded to supplement medium TSBA, 1/10 diluted TSBA, and TSB in comparison with 1/10 diluted TSB (p < 0.05) on polystyrene at 240 h (p < 0.05). In particular, the biofilm formation by L. monocytogenes (7.78 ± 0.03–8.82 ± 0.03 log10 CFU/cm2) was significantly different in terms of TSBA on polypropylene type B (PP) (p < 0.05). In addition, visualization by epifluorescence microscopy, scanning electron microscopy (SEM), and treatment (DNase I and proteinase K) revealed the metabolically active cells and extracellular polymeric substances of biofilms on PP. L. monocytogenes has the ability to develop biofilms that harbor virulence-associated genes, which represent a serious threat to human health and food safety.

Anti-Biofilm Activity of Cell Free Supernatants of Selected Lactic Acid Bacteria against Listeria monocytogenes Isolated from Avocado and Cucumber Fruits, and from an Avocado Processing Plant

“…The ability of the L. monocytogenes isolates from avocados and cucumbers to form biofilms is a cause for concern as it indicates their potential to persist in their respective environments and consequently pose a food safety risk due to their contamination of these produce. L. monocytogenes has been reported to form biofilms on apples, lettuce and cucumber [ 18 , 19 , 20 , 21 ].…”

“…Despite studies reporting the transmission of L . monocytogenes through fruits and vegetables [ 18 , 19 , 20 ]), specifically avocados [ 21 ] and cucumbers [ 22 ]; and the possession of anti-listerial properties by probiotics [ 4 , 14 , 16 ], there are no studies reporting the efficacy of probiotics in managing L. monocytogenes biofilms in avocado and cucumber processing plants. In light of these, this study aimed to screen the biofilm formation capabilities of L. monocytogenes strains from the avocado and cucumber environments and to evaluate the anti-biofilm effects of cell free supernatants (CFS) of selected lactic acid bacteria against the biofilms formed by these strains on different simulated food contact surfaces.…”

The ARIMA model approach for the biofilm-forming capacity prediction of Listeria monocytogenes recovered from carcasses

“…Internalin proteins are connected to the impact on biofilm in L. monocytogenes as well as its hydrophobicity, motility, virulence, internalization into eukaryotes and staying alive in different milieus [ 37 ]. Also, biofilm-formation markers including prfA , actA , inlA , and plcA play a remarkable part in the survival and persistence of L. monocytogenes [ 38 ]. Environmental parameters such as temperature may regulate genes with regard to virulence markers or structures that result in changes in the cell surface, which may impress compliance with the nascency of flagella in L. monocytogenes [ 39 ].…”

Prevalence and Antimicrobial Resistance of Listeria monocytogenes in Different Raw Food from Reynosa, Tamaulipas, Mexico

“…L. monocytogenes consists of four major evolutionary lineages (I, II, III and rare lineage IV), including 14 recognized serotypes that are grouped into four PCR serogroups [ 6 ].…”

“…The lineage I group contains serotypes 1/2b, 3b, and 4b and has greater pathogenic potential than lineage II, which is composed of serotypes 1/2a, 1/2c, 3a, and 3c. Lineage IV groups serotypes 4a and 4c and an atypical 4b [ 6 , 7 ].…”