The Laboratory for Molecular Biology of Foodborne Pathogens

Prof. Sima Yaron

The research of our team focuses on deepening the knowledge of various aspects related to virulence and resistance of foodborne and waterborne human pathogens.

The main objectives are directed to explore the survival mechanisms of pathogens at all food processing stages, “from the field to our gut”. Understanding derived from our research is essential for the development of innovative approaches to selectively damage pathogens, and simultaneously encourage the growth of beneficial bacteria, both in food and in our intestinal tract.

In contrast to the popular belief saying that fresh produce consumption is safe in relation to animal products such as meat and eggs, contaminated fruit and vegetables endanger the public’s health, because they are typically consumed fresh, without any thermal treatment. Various crops are exposed to human pathogens such as Salmonella in the field, because of the use of contaminated irrigation water, fertilizers, or following contact with other sources.

Our results indicate that Salmonella cells irreversibly attach to various plant parts (roots, leaves, fruits and seeds). Next they invade into the plant tissue, thus evade the plant defense response, and survive washing and disinfecting processes. Inhibition of the relevant pathways in Salmonella affects the survival capability of the bacteria in the short term and in the long term.

Food contamination may also occur during processing, or through transporting and storage in the factory, in the store or at home. Furthermore, conditions that might lead to an increase in bacterial numbers to levels that are defined as life-threatening may be developed at different stages from the field to the fork.  On the other hand, exposure of the bacteria to chemicals or other stresses at any stage of treatment, can lead to selection of resistant bacteria that survive antibiotic treatments in our body, or enrichment of genes that confer multiple resistance, which may transfer from indigenous bacteria to the pathogens. Identifying major hazard points in the field or during food processing enables developing means of controls and prevention for the benefit of the public health.

The multidisciplinary research in our lab includes advanced research tools in the fields of molecular biology, microbiology, food technology, biochemistry, bioinformatics, microbiome research, and bacterial-host interactions.

Main research topics are:

Microbial food safety:

Survival of pathogens in foodstuff, and development of novel methods for detection and inactivation of resistant pathogens.

Interactions between foodborne pathogens and leafy greens and herbs:

Identification of contamination sources, characterization of the bacteria-plant interactions, and molecular study of the factors affecting the attachment, invasion and survival of Salmonella in/on plants.

Microbial resistance of Salmonella:

Mechanisms of multiple resistance to antibiotics, food preservatives and sanitizing agents. Biofilm development on different surfaces, structure-function studies of bacterial biofilms, and the role of biofilm production in resistance of Salmonella to stress.

Gut microflora:

The effect of prebiotic and probiotic supplements on the composition of the intestinal microbiota of infants, with emphasis on reduction of pathogens.