Elucidating the mechanism of interaction of Salmonella with plants

Abstract

Salmonella, is an established pathogen of members of the kingdom Animalia. Its principal species S. enterica serovars Typhi, Paratyphi and Typhimurium can cause various diseases ranging from typhoid fever to gastroenteritis in different organisms. Post harvest contamination of fruits and vegetables by Salmonella is one of the causes of food-borne outbreaks. Controlling the spread of Salmonella at field level is very important in order to prevent various food-borne outbreaks. In this regard, the microbiota of plants can play a crucial role. In the present study, we made an effort to describe one such approach to limit Salmonella population in plant. Biocontrol of phyto-pathogens is an environmental friendly alternative to protect plants. Keeping this in view, endophytes from different organs of tomato plant (INDAM 535) were isolated and the growth of Salmonella was further analyzed in the culture supernatant of these endophytes. Spent media of Microbacterium paraoxydans and Lysinibacillus microides (isolated from roots) was found to have an inhibitory affect on Salmonella growth. These organisms were observed to reduce Salmonella CFU in arabidopsis as well as tomato roots. Their bacteriostatic activity was further verified. A quorum sensing/quenching based signaling between endophyte and Salmonella was observed. The second approach in controlling Salmonella colonization involves the antibacterial properties of the plant secondary metabolites. Beta vulgaris roots (a common salad vegetable) having high concentration of betalains was used to treat arabidopsis roots inoculated with Salmonella. Post treatment, a decrease in Salmonella burden was observed in roots of susceptible plants. These approaches can further be utilized to bring down the Salmonella population in soil. Thus, inclusion of these crops in the crop rotation or as a mixed/inter crop can be a fruitful tool to reclaim the Salmonella contaminated soil.