Lysinibacillus Macroides-Mediated Control of Cellulose-Producing Morphotype of Salmonella.

BACKGROUND Soil dwelling human pathogens like Salmonella are transmitted by fresh produce like tomato, spinach, onion, cabbage etc. With >2600 serovars, it is difficult to classify the good plant colonizers from the non-colonizers. Generally, soil microbiota is classified as autochthonous or zymogenous organisms, based on their ability to survive in soil. However, such information for soil-dwelling human pathogens is not available Thus, there is a need to classify these organisms for designing a strategy to prevent their outbreak. Moreover, soil harbours a plethora of microbes, which can be screened for competitive organisms to control such human pathogens. RESULTS In this study, we examined if the morphotype based on the attachment factors (like cellulose and curli fimbri) of Salmonella was important for its colonization of roots. Secondly, we tracked the location of the bacteria in the plant cell. Interestingly, most of the epidermal cells occupied by Salmonella showed propidium iodide-positive nuclei. As an extension of the study, a screening of competitive rhizospheric bacteria was performed. One isolate identified as, Lysinibacillus macroides, was able to inhibit the biofilm of Salmonella and subsequently reduced its colonization on roots. CONCLUSION Based on this study, we classified the Rdar morphotypes as good plant colonists. The ability to colonize the live plant cell and subsequent kill throw light on the zymogenous life cycle of soil-dwelling Salmonella. Additionally, Lysinibacillus macrolides served as a biocontrol agent by reducing the burden of Salmonella in various vegetables. Such organisms can further be explored to prevent contamination of the food chain. This article is protected by copyright. All rights reserved.