PSI-7 Characterization of Bile Induced Damage in Listeria monocytogenes.

摘要

is a Gram positive, facultative intracellular organism responsible for silage disease in animals, meningitis, abortion and still birth. Infections caused by in livestock lead to heavy economic losses. must survive a variety of stressors encountered within the gastrointestinal tract, including variations in pH, oxygen availability, and bile, to cause these diseases. Studies have shown that exposure to bile may regulate virulence factors in . However, the link between the bile stress response and virulence in is poorly understood. This study tested the hypothesis that strains considered virulent have greater resistance against bile induced oxidative damage. To test this hypothesis, protein and lipid oxidative damage induced by bile was analyzed in three different strains of with varied virulence potential: HCC23, 10403S, and F2365. Protein carbonylation was measured using the Protein Carbonyl Content Assay. Briefly, cells were treated with and without 0.3% bile under aerobic and anaerobic conditions for one hour and the carbonyl content was determined by derivatization of protein carbonyl groups with 2,4-dinitrophenylhydrazine, leading to the formation of stable dinitrophenyl hydrazine adducts that were then measured spectrophotometrically at 375 nm. Lipid peroxidation was determined by measuring the quantity of the reactive aldehyde malondialdehyde in bile treated cultures under both aerobic and anaerobic conditions using the Lipid Peroxidation Assay kit. A minimum of three independent replicates were performed for both experiments. Results suggested that bile caused an increase in protein carbonyl content in F2365 only under aerobic conditions and that there was no peroxidation of the lipids, possibly due a lack of unsaturated fatty acids. Though the data suggests bile induces oxidative damage on F2365 under aerobic conditions, further investigation of DNA damage under aerobic and anaerobic conditions is needed to analyze the effect of bile on .