Affiliation: College of Arts and Sciences, Department of Biology
Listeria monocytogenes (LM) is a human pathogen and agent of listeriosis, a foodborne illness that can cause severe complications and death in immunocompromised individuals such as pregnant women and the elderly. LM has one of the highest mortality rates of foodborne illnesses, with 30% of patients dying due to infection. LM occurs ubiquitously in the environment, where it can attach to crops and infect animals that are ultimately consumed by humans. LM contamination of food products not only poses a major threat to human health, but to the food industry as well, costing between $2.3 and $22 billion per year.
Current research on LM largely investigates the clinical aspects of LM infection not LM in true environmental settings. Thus, little is known about LM in the environment and how it interacts with the flora and other soil microbes. To investigate LM plant colonization, we performed a hydroponic assay in which Arabidopsis thaliana seedlings were suspended in media and inoculated with LM. We first tested a range of media and found LM readily colonizes A. thaliana in minimal media. Next, we investigated the impact of coculturing LM with other soil microbes and found that one of the organisms we tested may increase LM plant colonization. Lastly, we investigated the persistence of LM on the plant root by measuring colony-forming units (CFUs) at different time points, both in monoculture and in coculture with other soil microbes. We found that LM persists on the plant root with no significant decrease in CFUs up to 72 hours after colonization. However, further experiments are required to conclude the effects of additional soil microbes on LM persistence. These data demonstrate LM readily colonizes A. thaliana in this hydroponic assay, that LM persists on the plant root following colonization, and that coculturing with other microbes may impact LM colonization.