Phosphodiesterase D Is Involved In Bile Resistance In Listeria monocytogenes
Sophia Ali1, Damayanti Chakravarty2, Janet R. Donaldson2
1Mississippi INBRE Research Scholar, School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS
2School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS
Listeria monocytogenes is a deadly foodborne pathogenic bacterium that is responsible for almost 20% of food related deaths in the United States. Listeria monocytogenes contaminates ready-to-eat products such as cheese and ice cream. Once ingested, it invades the intestinal lining and can enter the bloodstream, causing listeriosis. There is a gap in the knowledge of the pathogenesis of L. monocytogenes and how it is able to survive in the gastrointestinal tract in the presence of bile, which has bactericidal properties. Previous studies have suggested that the second messenger cyclic-di-GMP may be involved in the regulation of virulence factors of this bacteria. This nucleotide is produced by diguanylate cyclase and degraded by phosphodiesterase D (PdeD). The purpose of this investigation is to determine how the PdeD mutant survives in the presence of bile under aerobic and anaerobic conditions in neutral and acidic pH. Survival of the wild-type strain and a pdeD mutant was analyzed in aerobic and anaerobic conditions in neutral and acidic pH with and without 1% bile to mimic locations within the body where bile would be present (i.e. duodenum and gall bladder). Preliminary results show that the pdeD mutant is more sensitive to bile in aerobic and neutral conditions than the wild type. In order to better understand the relationship between PdeD and bile, future directions include studying the gene expression of bile resistance genes, such as BilE and BSH, using timepoints based on the data from this study.