Improvement of methods for the detection of Gram-negative foodborne pathogens

Promotie

De verbetering van de detectie van voedselgerelateerde ziekteverwekkers

Promovendus H (Heike) Margot
Promotor prof.dr.ir. MH (Marcel) Zwietering
Copromotor Han Joosten
Copromotor prof. dr R Stephan
Organisatie Wageningen University, Food Microbiology Laboratory
Datum

vr 16 september 2016 11:00 tot 12:30

Locatie Aula, gebouwnummer 362
Generaal Foulkesweg 1
362
6703 BG Wageningen
0317-483592

A major proportion of foodborne disease is caused by Gram-negative bacteria such as Salmonella and Shiga toxin-producing E. coli. The ability to detect these pathogens is an important aspect in the verification of food safety. In this thesis, the detection of Gram-negative foodborne pathogens is addressed by looking at the steps from enrichment to detection.

One challenge in the detection of pathogens is the numerical dominance of the natural flora of food products. To get a better insight in the enrichment ecology of STEC in sprouts, the microbiome of sprouts was analysed using Illumina HiSeq sequencing prior to and during the enrichment in different media.

With the application of a selective medium, growth of the competitive microflora that complicates the detection of STEC was promoted. Enrichment in EE-broth also resulted in good growth of STEC however, the situation of low maximum population densities of the target strain in the matrix was still present.

This thesis provides a critical evaluation of rapid methods and new insights on enrichment procedures, the role of competitors in bacterial enrichment procedures and the limitations of selective agents.