Whole Genome Sequence Analysis of Phage-Resistant Listeria monocytogenes Serotype 1/2a Strains from Turkey Processing Plants.

Phillip Brown,Eric Brown,Martin J Loessner,Yang Shen,Yi Chen,Sophia Kathariou,Cameron Parsons

doi:10.3390/pathogens10020199

Abstract

Listeria monocytogenes is a Gram-positive bacterial pathogen and the causative agent of listeriosis, a severe foodborne infection. L. monocytogenes is notorious for its ability to persist in food processing environments (FPEs) via a variety of adaptive traits. Even though traits such as cold tolerance, biofilm formation and sanitizer resistance have been extensively investigated for their roles in persistence of L. monocytogenes in FPEs, much less is known about resistance to bacteriophages. Previous studies explored phage resistance mechanisms in laboratory-created mutants but it is imperative to investigate phage resistance that is naturally exhibited in FPE-derived strains. Here, we integrated the analysis of whole genome sequence data from a panel of serotype 1/2a strains of sequence types 321 and 391 from turkey processing plants, with the determination of cell surface substituents required for phage adsorption and phage infection assays with the four wide-host-range phages A511, P100, 20422-1 and 805405-1. Using a specific set of recombinant phage protein probes, we discovered that phage-resistant strains lacked one or both of the serogroup 1/2-specific wall teichoic acid carbohydrate decorations, N-acetylglucosamine and rhamnose. Furthermore, these phage-resistant strains harbored substitutions in lmo1080, lmo1081, and lmo2550, which mediate carbohydrate decoration of the wall teichoic acids.

Highlights

Listeria monocytogenes is a Gram-positive facultative intracellular pathogen found ubiquitously in nature and is notorious for its capacity to persist in food processing environments (FPEs)
Contamination of FPEs is critical for contamination of ready-toeat foods by L. monocytogenes, with the potential to lead to outbreaks of the severe and potentially life-threatening foodborne disease listeriosis [1,2,3]
In L. monocytogenes and other bacteria, the latter can include prophages, bacteriophage exclusion (BREX) systems, defense island system associated with restriction-modification (DISARM) systems and clustered, regularly interspaced, short palindromic repeats (CRISPR) systems [13,14,15,16,17,18,19]

Summary

Introduction

Listeria monocytogenes is a Gram-positive facultative intracellular pathogen found ubiquitously in nature and is notorious for its capacity to persist in food processing environments (FPEs). L. monocytogenes has the ability to persist in FPEs via multiple adaptations, including its ability to grow at low temperatures, to form biofilms and tolerate sanitizers [4,5,6,7,8]. Even though such adaptive traits have been extensively investigated, the potential roles of bacteriophage (phage) resistance in the persistence of this pathogen in FPEs remains poorly understood. Phage resistance in L. monocytogenes can be mediated by failure of the phage to adsorb to its specific receptors via receptor loss or modification, and various post-infection intracellular resistance mechanisms [10,11,12]. In L. monocytogenes and other bacteria, the latter can include prophages, bacteriophage exclusion (BREX) systems, defense island system associated with restriction-modification (DISARM) systems and clustered, regularly interspaced, short palindromic repeats (CRISPR) systems [13,14,15,16,17,18,19]

Objectives

Methods

Results