University of Zürich

Tuesday, November 2, 2010

University of Zürich

Seminar on Food Microbiology

In collaboration with the Vetsuisse Faculty (Vetsuisse-Fakultät) at University of Zurich a joint seminar with researchers of Institute for Food safety and Hygiene (Lebensmittelsicherheit und -hygiene, Institut für) and us was held on Tuesday, Nov 2nd. Due to misleading of campus reception staff, we were 25 minutes late.  The seminar was opened by Prof. Dr. Roger Stephan, the head of the institute. He gave a brief introduction about the organization structure of Vetsuisse Faculty and main research fields of Institute for Food safety and Hygiene including risk assessment in food chain, molecular methods improvement, adaptation and stress response of pathogens and their antibiotic resistance. Shiga-toxin producing E. coli (STEC), L. monocytogenes, S. aureus and Cronobacter spp. are currently their main target pathogens.

The first scientific presentation “Investigation of molecular cold stress response mechanism in L. monocytogenes” was given by Dr. Taurai Tasara. After introduction of the organism and mechanisms contributing its stress tolerance, he firstly dropped the attention to the role of cold shock proteins (Csps) in growth of L. monocytogenes under cold and osmotic stress conditions. Then on-going investigation on role of a δ-factor RpoN (δL) was discussed. Clint van Melis (WUR) presented the progress of his study about heterogeneity in germination and outgrowth of organic acid-stressed Bacillus cereus spores. The second speaker from Dr. Stephan’s group is Silvio Peng, who is initiating his study on stress response mechanism of STEC in the process of raw-milk-cheese production. An insight of bacterial response mechanisms to general stress (δ-factor RpoS), acid stress (proton consumption and antiporters), osmotic stress (compatible solutes) and high temperature (heat shock proteins, δ-factor RpoH) was introduced.

The next talk titled “Diagnostic test performance” was from Dr. Sonja Hartnack. She firstly introduced background knowledge in diagnostic test, including important parameters and their functions. Then the way to evaluate certain diagnostic test performance was discussed with her experience, which is very valuable for us to select good test method in our research. Then Greetje Castelijn from our group presented her study on Salmonella biofilms showing that curli fimbriae and cellulose production of Salmonella Typhimurium are influenced by environmental conditions and affect biofilm formation.

After lunch break, Sachin Kadam (WUR) showed the capability of L. monocytogenes strains to form mixed species biofilms with various other bacterial species and the difference from the single-specie biofilms. Then Dr. Sophia Johler gave a presentation titled “Microarray-based comparison and spa typing of bovine, porcine and food poisoning outbreak isolates of Staphylococcus aureus”. At last Prof. Dr. Marcel Zwietering introduced Wageningen UR, research activities within Laboratory of Food microbiology and our PhD trip. A lab tour was offered by Prof. Stephan before we left University of Zurich campus.

(Xiao Yinghua)