M61 The use of PolyTransport technology to reduce the bioavailability of iron to enteric pathogens Jessica Brown*^1GS, Ashley Tarcin¹, Rachel Ganske¹, Joshua Jendza², Eric Neeno-Eckwall³, Jessica Hite³, Steven Ricke^{1 1}Meat Science and Animal Biologics Discovery, Department of Animal and Dairy Sciences, University of Wisconsin Madison, ²Qualitech Inc., ³School of Veterinary Medicine, Department of Pathobiological Sciences, University of Wisconsin-Madison

Dietary supplementation with iron is routine in the poultry industry. However, supplemental iron not only supports the host but also the microbial community within the gut. This can lead to an internal competition between host and gut pathogens for bioavailable iron sources. Iron also plays a role in virulence regulation in intestinal pathogens, magnifying the significance of this competition. The objective of this study was to evaluate the ability of the PolyTransport technology in SQM iron, a metal polysaccharide complex, to reduce the bioavailability of iron to Salmonella and E. coli in an in vitro system. Nine Salmonella and four E. coli were grown as individual overnight cultures. A 96-well plate was prepared with the following treatments: (1) 2, (2) 5, (3) 10ppm SQM w/o Fe, (4) 2, (5) 5, (6) 10ppm SQM, (7) 2, (8) 5, (9) 10ppm FeSO4, (10) -CTRL, (11) +CTRL. Treatments were diluted in sterile water and combined (1:1) with 2× LB broth, chelated (1-11) with 100ppm 2,2-dipyridyl or unchelated (12). A pin replicator was used to inoculate the treatment plate before being incubated for 24 h at 37°C in a TECAN Infinite 200 Pro with OD measurements taken at 600nm every 10 min. Growth rates were calculated in R Studio using growthrates linear fit function. Three independent replicates were performed for each strain and data was analyzed in a linear mixed effect model with means separated by Sidak (P≤0.05). In four of nine Salmonella strains, the 10ppm SQM treatment reduced the rate of growth compared to the 10ppm FeSO4 treatment (0.46-0.57 and 0.57-0.67 lnOD/h; P<0.05). While significant effects were not observed in all Salmonella strains, numerically, the growth rates observed for the SQM treatments were consistently lower than those in the FeSO4 equivalent. E. coli was less impacted by the PolyTransport technology, as three of the four strains did not exhibit growth rate differences between SQM and FeSO4 treatment (P>0.05). The SQM matrix itself did not appear to have any innate antimicrobial properties beyond the restriction of iron. It can be concluded that the PolyTransport technology can restrict iron bioavailability to pathogenic bacteria within an in vitro system; however, growth rates and efficacy may vary due to iron dependency and sequestration systems.

Key Words: Salmonella, E. coli, Iron, Nutrient Bioavailability