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Characterization of a potential Listeria monocytogenes virulence factor associated with attachment to fresh produce.

ABSTRACT: A study to determine the attachment of L. monocytogenes serotype 4b strain F2365 on vegetables and fruits was conducted. In an initial study, we screened 32 genes encoding surface proteins and lipases of the strain to find highly expressed genes on lettuce leaves. The results showed that transcription levels of LMOf2365_0413, LMOf2365_0498, LMOf2365_0859, LMOf2365_2052, and LMOf2365_2812 were significantly upregulated on lettuce leaves. In silico analysis showed that LMOf2365_0859 contains a putative cellulose binding domain. Thus, we hypothesized that this gene may be involved in an attachment to vegetables, and named it lcp (gene encoding Listeria cellulose binding protein [LCP]). lcp mutant (?lcp) and lcp complement (F2365::pMAD::cat::lcp) strains were generated by homologous recombination. The abilities of a wild-type (WT) strain, the ?lcp strain, and the complemented strain to attach to lettuce leaves were evaluated, which indicated that the attachment of the ?lcp strain to lettuce was significantly less than that of the WT and the complemented strains. Similar results were observed for baby spinach and cantaloupe. Fluorescence microscopy and field emission scanning microscopy analysis further supported these findings. The binding of L. monocytogenes to cellulose was determined using cellulose acetate-coated plates. The results showed that a binding ability of the ?lcp strain was significantly lower than that of the wild type. Combined, these results strongly suggest that LCP plays an important role in an attachment to vegetables and fruits.

SUBMITTER: Bae D

PROVIDER: S-EPMC3811550 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature

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Characterization of a potential Listeria monocytogenes virulence factor associated with attachment to fresh produce.

Bae Dongryeoul D Seo Keun Seok KS Zhang Ting T Wang Chinling C

Applied and environmental microbiology 20130823 22

A study to determine the attachment of L. monocytogenes serotype 4b strain F2365 on vegetables and fruits was conducted. In an initial study, we screened 32 genes encoding surface proteins and lipases of the strain to find highly expressed genes on lettuce leaves. The results showed that transcription levels of LMOf2365_0413, LMOf2365_0498, LMOf2365_0859, LMOf2365_2052, and LMOf2365_2812 were significantly upregulated on lettuce leaves. In silico analysis showed that LMOf2365_0859 contains a put ...[more]

PMID: 23974144

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Project description:Whole and fresh-cut produce are minimally processed and susceptible to microbial contamination. This study evaluated the survival or growth of L. monocytogenes on peeled rinds, and fresh-cut produce at different storage temperatures. Fresh-cut fruits and vegetables, including cantaloupe, watermelon, pear, papaya, pineapple, broccoli, cauliflower, lettuce, bell pepper, and kale (25 g pieces) were spot inoculated with 4 log CFU/g of L. monocytogenes and stored at 4 or 13°C for 6 days. Cantaloupe and bell pepper rind disks (20 cm2), mimicking whole produce were inoculated with low inoculum level (4 log CFU/mL) and high inoculum level (6 log CFU/mL) and stored at 24°C up to 8 days and 4°C up to 14 days, respectively. L. monocytogenes counts on fresh-cut pear samples stored at 4°C increased significantly by 0.27 log CFU/g. However, Listeria levels on kale (day 4), cauliflower (day 6), and broccoli (day 2) were significantly reduced by 0.73, 1.18, and 0.80 log CFU/g, respectively, at 4°C. At 13°C, the bacterial counts increased significantly after a day of storage on fresh-cut watermelons (increasing by 1.10 log CFU/g) and cantaloupes (increasing by 1.52 log CFU/g). Similar increases were observed on pears (1.00 log CFU/g), papayas (1.65 log CFU/g), and green bell peppers (1.72 log CFU/g). Pineapple samples did not support the growth of L. monocytogenes at 13°C with a significant reduction of 1.80 log CFU/g by day 6. L. monocytogenes levels significantly increased in fresh-cut lettuce at 13°C but remained stable on kale, cauliflower, and broccoli after 6 days of storage. Stable population was observed also on cantaloupe rinds up to 8 days at 24°C. While on the outer surface of bell peppers, the population level decreased below the detectable limit of the test (10 CFU/20 cm2) after 14 days of storage at 4°C. The results demonstrated variable survival behavior of L. monocytogenes on fresh-cut produce with produce type and storage temperature.

Dataset Information

Characterization of a potential Listeria monocytogenes virulence factor associated with attachment to fresh produce.

Publications

Characterization of a potential Listeria monocytogenes virulence factor associated with attachment to fresh produce.

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