Synthesis and Evaluation of the Immunomagnetic Beads for Separation of the Salmonella typhimurium from Milk

Salmonella causes zoonotic diseases in humans and many animal species. The bacteria could be spread through fecal-oral transmission and consumption of raw contaminated animal products. Despite the activities which are carried out for the prevention of salmonellosis, it causes economic losses. This study aimed to prepare immunomagnetic beads to separate the Salmonella bacteria from experimentally polluted milk samples. The antibodies were purified from the rabbit's hyperimmune sera and coupled to the Fe nanoparticles using diethylenetriaminepentaacetic acid (DTPA) as a linker. The synthesized particles were analyzed using electron microscopy. The limit of bacterial detection by using the immunomagnetic beads coupled with bacterial culture were tested in experimentally contaminated cow milk with Salmonella. The separated bacteria were identified by using bacterial culture and biochemical tests. Using immunomagnetic beads (IMB), the Salmonella bacteria were removed from milk samples, concentrated in sterilized PBS, and cultured in nutrient agar media. The conventional culture method detected the bacteria in samples polluted with at least 3×104 CFU/mL bacteria; however, isolated bacteria were separated from milk samples using IMB and defined on bacterial culture media. The 3 CFU/mL of S. Typhimurium were detected in experimentally polluted milk samples using the current immunomagnetic-culture method. The results suggested using the IMB-bacterial culture instead of the conventional culture method.