Characterization of Listeria prophages in lysogenic isolates from foods and food processing environments

PLoS One. 2019 Apr 1;14(4):e0214641. doi: 10.1371/journal.pone.0214641. eCollection 2019.

Abstract

Prophages are commonly found in Listeria genomes, potentially enhancing survival or fitness of Listeria spp. Currently, there is still limited information on the distribution of prophages among Listeria isolates of different allelic types and from various sources. In this study, by using mitomycin C induction, prophages were found in 23/144 isolates (16.0%), including 13 L. monocytogenes and 10 Listeria spp. isolates, resulting in 28 and 11 induced phages, respectively. These prophage-carrying isolates (lysogens) were obtained from foods and food-related environments presenting 3 common allelic types (ATs) of L. monocytogenes (lineage I, II and IV), 4 ATs of L. innocua and 1 AT of L. welshimeri. The likelihood of prophage-carrying isolates of L. monocytogenes was 14.4 (95% CI: 4.9-35.4), and 18.5 (95% CI: 4.8-50.2) for Listeria spp. The 39 induced phages were classified into 3 lysis groups by the host range test against 9 major serotypes of L. monocytogenes and 5 species of Listeria. Most phages were host-specific with higher ability to lyse L. monocytogenes serotype 4 than other serotypes. The genome size of phages ranged from 35±2 kb to 50±2 kb and belonged to two common phage families, Myoviridae and Siphoviridae. Restriction analysis classified 19 selected phages into 16 restriction profiles, suggesting highly diverse prophages with at least 16 types. This may contribute to the variation in the genomes of Listeria. Information obtained here provides basic knowledge for further study to understand the overall role of prophages in Listeria, including roles in survival or fitness in foods and food processing environments.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Typing Techniques
  • Bacteriophages / genetics
  • Bacteriophages / isolation & purification
  • Environmental Microbiology
  • Food / classification
  • Food Handling* / standards
  • Food Microbiology*
  • Food-Processing Industry
  • Genome Size
  • Host Specificity
  • Humans
  • Listeria monocytogenes / genetics
  • Listeria monocytogenes / isolation & purification
  • Listeria monocytogenes / virology
  • Listeria* / classification
  • Listeria* / genetics
  • Listeria* / isolation & purification
  • Listeria* / virology
  • Lysogeny* / genetics
  • Phylogeny
  • Prophages / genetics
  • Prophages / isolation & purification*
  • Sigma Factor / genetics

Substances

  • SigB protein, Listeria monocytogenes
  • Sigma Factor

Grants and funding

This project is financially supported by the Higher Education Research Promotion and the Thailand’s Education Hub for Southern Region of ASEAN Countries Project Office of the Higher Education Commission (to HTKV). Funding from Prince of Songkla University (AGR600584S; to KV) and the TRF Distinguished Research Professor Grant (to SB) is also acknowledged.