ena-STUDY-Milk Technology-30-10-2014-08:58:50:139-323
KEY FEATURES FOR THE ADAPTION AND SURVIVAL OF LISTERIA MONOCYTOGENES IN THE DAIRY PROCESSING ENVIRONMENT
Persistent L. monocytogenes and Listeria spp. isolates (characterized by PFGE and MLST typing) are hypothesized to be better adapted to the food producing environment (FPE).  Therefore, the whole genome of 15 L. monocytogenes and Listeria spp. strains established in the same food processing environment was sequenced applying the Illumina sequencing technique.  The L. monocytogenes core-genome of the 12 selected strains was highly syntenic. Differences were detected in mobile elements of the accessory genome. Eight L. monocytogenes and two L. innocua strains indicated the presence of 15-90 kbp plasmids. The long-term L. monocytogenes persistent strains, assigned to genetic lineage I [sequence type (ST) 5] and lineage II (ST204), harbored a plasmid comparable to plm80. All strains included fragments of the non-lytic bacteriophage A118, L. monocytogenes ST9 and L. innocua also implicated genes of Listeria phage 2389. When comparing L. monocytogenes ST37 at the beginning and the end of isolation, the loss of a distinct phage region (~33 kpb) was noticeable. The bcrABC cassette was detected in the plasmids of L. monocytogenes ST204 (n=1) and ST5 strains (n=6). The transposon Tn554, suspected for benzalkonium resistance, was found in L. monocytogenes ST9, one L. innocua, and L. seeligeri. The L. monocytogenes stress-survival islet (SSI-1) was present in ST5, ST204, and ST9.   The results indicate mutations in the L. monocytogenes ST5, ST37 phage and/or plasmid genome suspected for better adaption and survival in the particular FPE. Additionally, gene regions for better adaption to disinfectants and acidic stress (Tn554, SSI-1) were found in long term persistent L. monocytogenes strains.
Persistent L. monocytogenes and Listeria spp. isolates (characterized by PFGE and MLST typing) are hypothesized to be better adapted to the food producing environment (FPE).  Therefore, the whole genome of 15 L. monocytogenes and Listeria spp. strains established in the same food processing environment was sequenced applying the Illumina sequencing technique.  The L. monocytogenes core-genome of the 12 selected strains was highly syntenic. Differences were detected in mobile elements of the accessory genome. Eight L. monocytogenes and two L. innocua strains indicated the presence of 15-90 kbp plasmids. The long-term L. monocytogenes persistent strains, assigned to genetic lineage I [sequence type (ST) 5] and lineage II (ST204), harbored a plasmid comparable to plm80. All strains included fragments of the non-lytic bacteriophage A118, L. monocytogenes ST9 and L. innocua also implicated genes of Listeria phage 2389. When comparing L. monocytogenes ST37 at the beginning and the end of isolation, the loss of a distinct phage region (~33 kpb) was noticeable. The bcrABC cassette was detected in the plasmids of L. monocytogenes ST204 (n=1) and ST5 strains (n=6). The transposon Tn554, suspected for benzalkonium resistance, was found in L. monocytogenes ST9, one L. innocua, and L. seeligeri. The L. monocytogenes stress-survival islet (SSI-1) was present in ST5, ST204, and ST9.   The results indicate mutations in the L. monocytogenes ST5, ST37 phage and/or plasmid genome suspected for better adaption and survival in the particular FPE. Additionally, gene regions for better adaption to disinfectants and acidic stress (Tn554, SSI-1) were found in long term persistent L. monocytogenes strains.