Publikationsdatenbank

Prevalence and cold shock response of Arcobacter spp. (2021)

Art

Hochschulschrift

Autor

Zhang, Xiaochen (WE 8)

Quelle

Berlin: Mensch und Buch Verlag, 2021 — x, 89 Seiten

Sprache

Englisch

Verweise

URL (Volltext): https://refubium.fu-berlin.de/handle/fub188/30148

Kontakt

Institut für Lebensmittelsicherheit und -hygiene

Königsweg 69
14163 Berlin
+49 30 838 62551 / 52790
lebensmittelhygiene@vetmed.fu-berlin.de / fleischhygiene@vetmed.fu-berlin.de

Abstract / Zusammenfassung

Arcobacter (A.) spp. was regarded as an emerging pathogen associated with enteritis, diarrhea and occasionally bacteremia in human. It has been widely isolated from animals, foods and water environment. In the recent ten years, more than half of the newly described species of this genus were recovered from aquatic environments and water-borne animals. Therefore, the occurrence of Arcobacter in seafood has raised increasing interest for food safety concern. Consuming undercooked or preparing raw seafood was regarded as a potential risk of human transmission. Despite the frequent reports of this genus from food, the knowledge of its pathogenicity and the cold stress response is still scarce. This work aimed to evaluate the prevalence of Arcobacter spp. in retail seafood in Berlin, and to characterize all isolates by the genetic diversity and the distribution of 10 putative virulence genes. In addition, the growth of A. butzleri isolates from different origins was tested at chilling temperature. The presence and transcriptional expression profile of 13 cold-related genes homologues in E. coli were preliminarily reported in A. butzleri. Chapter 1 introduces a comprehensive literature review on the taxonomy, occurrence, current isolation and typing methods of Arcobacter spp. The information about virulence determinants, cold adaptation of A. butzleri as well as cold-related genes in E. coli is also provided. In the first study (Chapter 2), the overall prevalence of Arcobacter in retail seafood was 17.6%. For each food matrix, cephalopod was found to have the highest prevalence (27.4%) and species diversity (6 species) followed by bivalves (17% and 5 species) and shrimp (8.5% and 4 species). High genetic heterogeneity was observed both at inter- and intra-species level. A. butzleri was found to carry most putative virulence genes and the gene ciaB was 100% detected in all Arcobacter isolates. No correlation between the ERIC-PCR pattern/virulence gene distribution and the source of the isolates can be deduced. The cold adaptation of A. butzleri was further investigated in Chapter 3. The growth of eight A. butzleri isolates from human, mussel and chicken was tested at 8°C under aerobic condition to mimic natural environment for food storage at chilling temperatures. One A. butzleri strain (H2) showed growing capability at this temperature while most of others (6/8) were not culturable after 28 days under these culture conditions. No correlation between the growth and / or survival behavior and the source of A. butzleri isolates was observed, and the growth of A. butzleri at 8°C under aerobic circumstance in our study seemed to be strain-dependent. The transcriptional expression pattern of 13 cold-related genes in E. coli was also investigated in three A. butzleri strains with different growth mode after a temperature downshift to 8°C by RT-qPCR. Several similarities in the cold-related genes expression pattern of A. butzleri with E. coli were determined. For elucidating whether similar functions of these genes in A. butzleri at cold were utilized, further investigation was needed. To summarize, our research provide more information to estimate whether consumption/handling of seafood have a potential risk for human health and help to better understanding the survival strategy of A. butzleri encountering to cold stress.