Effects of iron and selenium on the production of catalase, superoxide dismutase, and listeriolysin O in Listeria monocytogenes

Listeria monocytogenes 19112, Scott A, and 10403S were grown in tryptic soy broth (TSB) and TSB supplemented with 25 to 100 mu g/ml of iron (Fe) and 0 .5 to 2.5 mu g/ml selenium (Se) to examine the effects on catalase (CA), su peroxide dismutase (SOD), and listeriolysin O (LLO) activities. Growth in T SB supplemented with Fe resulted in significant increases in CA, SOD, and L LO activities in all three strains when compared to growth in TSB. The addi tion of 0.5 mu g/ml Se to TSB resulted in significantly higher CA and LLO a ctivities in L. monocytogenes 19112 but showed no effect on Scott A or 1040 3S. These results suggest that Fe plays a role in increasing the activities of CA, SOD, and LLO.