Salmonella persistence in soil depends on reciprocal interactions with indigenous microorganisms.

Abstract

Fresh fruits and vegetables have numerous benefits to human health. Unfortunately, their consumption is increasingly associated with food-borne diseases, Salmonella enterica being their most frequent cause in Europe. Agricultural soils were postulated as reservoir of human pathogens, contributing to the contamination of crops during the growing period. Since the competition with the indigenous soil microbiota for colonization sites plays a major role in the success of invading species, we hypothesized that reduced diversity will enhance the chance of Salmonella to successfully establish in agricultural environments. We demonstrated that the abundance of Salmonella drastically decreased in soil with highly diverse indigenous prokaryotic community, while in soil with reduced prokaryotic diversity, Salmonella persisted for a long period. Furthermore, in communities with low diversity, Salmonella had an impact on the abundance of other taxa. The high physiological plasticity allows Salmonella to use agricultural soils as alternative habitat which might provide a route of animal/human infections. In addition, adjusted transcriptional profile with amino acid biosynthesis and the glyoxylate cycle most prominently regulated, suggests an adaptation to the soil environment. Our results underline the importance of the maintenance of diverse soil microbiome as a part of strategy aiming at reduced risk of food-borne salmonellosis outbreaks.