Factors influencing the Salmonella internalization into seedpods and whole plants of Arachis hypogaea (L.)

Here we investigated whether Salmonella enterica serovar Typhimurium ATCC 14028 was capable of internalizing in peanut seedpods and plants when exposed to inoculated soil and the edaphic factors that influenced uptake. Intact dry Virginia (DV) and fresh green Virginia (GV) seedpods were exposed to soil containing 6.5 Log (CFU/g) Salmonella under different soil moisture conditions. Internalization of S. Typhimurium into peanut plants germinated in inoculated soil was also examined with and without Bradyrhizobium (Arachis) sp.NC92. Salmonella counts recovered from GV seedpods were on average of 2.0 Log (CFU/pod) less than those recovered from DV seedpods. The internalization in DV pods was only observed at soil water content of 15% or greater in a loamy sand soil. S. Typhimurium was detected inside peanut plant tissues during most testing times. Cells were recovered from stem samples (3.5 Log CFU/g) at greater levels than it was observed for root (2.6 Log CFU/g) and leaf (1.7 Log CFU/g) samples. Overall, recovery of Salmonella from stem, root, and leaf samples were lower when B. NC92 was inoculated on seeds before sowing, but this trend was not significant. Our observations suggest possible routes of contamination of Salmonella into peanut products from soil.