ChitinOMix: The effect of chitin soil amendment on the plant response, natural microbial community and the fate of human pathogenic bacteria (CHITINOMIX)

Can the natural substance chitin have a beneficial effect in a soil substrate for the cultivation of leafy vegetables, especially as a natural growth inhibitor of Salmonella? This research question is posed in the project ChitinOMix, in the framework of the sustainable improvement of food safety of raw consumed vegetables. We investigate the effect of chitin as a substrate additive on the plant response, the plant microbial communities and human pathogenic bacteria. Chitin is found in the shrimp peelings and in the shells of lobster and crab.  In nature, chitin is the most common biopolymer after cellulose. When chitin is extracted from waste streams such as shrimp and crab shells, it contributes to the recycling of waste.
 
 

To identify and consolidate the causal relationships of the effect of chitin as a substrate additive on the survival of Salmonella, we use innovative and challenging 'OMICS' approaches (such as shotgun metagenomics, dual RNA-seq combined with metabolomics) and classical culture-dependent microbiology. As a model pathogen we choose Salmonella, given the number of Salmonella outbreaks related to the consumption of fresh vegetables. Lettuce is chosen as a model crop for a freshly consumed leafy vegetable. In parallel, we also perform experiments on the Arabidopsis model, in order to compare the results on lettuce with the known fundamental knowledge on the molecular mechanisms of chitin perception and plant immunity.

Nutritionists encourage the consumption of fresh and raw vegetables as part of a healthy diet. However, it has also been established that human pathogens such as Salmonella enterica are able to survive on plants and thus can infect fresh vegetables. In recent years, more food infections related to the consumption of Salmonella-contaminated fresh vegetables have been reported. Preventing or reducing contamination before harvesting is the most important step to reduce the health risk. Recently, there are indications that adding chitin to the soil may reduce the survival of Salmonella on the leaves of lettuce plants. With this ChitinOMix project it becomes clear to what extent chitin may contribute to an actual natural suppression of Salmonella in soil and leafy vegetables. If the results are promising, prospects open up for a useful valorisation of shrimp and crab shells, which are now considered a low-grade residual stream.