2004 Volume 21 Issue 1 Pages 14-22
Radish, cress and alfalfa seeds contaminated with Escherichia coli O157 and Salmonella Enteritidis were stored at 4°C for 8 months. As a result, at contamination levels of 104 colony forming units (cfu) /10g, populations of S. Enteritidis in all seeds and those of.E. coli O157 in cress seeds were maintained for up to 8 months. When the seeds were grown, the edible parts of sprouts were heavily contaminated with the microorganisms. Although the population of E.coli O157 in radish and alfalfa seeds had greatly decreased, the microorganism was detected in the edible parts of sprouts from the seeds. At contamination levels of 102 cfu/10g, S. Enteritidis survived in alfalfa seeds at low population levels for up to 8 months and were detected at high population levels in sprouts from the seeds. These results suggested that E. coli O157 and S. Enteritidis could survive in seeds refrigerated for a long time and contaminate the sprouts from the seeds. Furthermore, E. coli O157 and S. Enteritidis were able to grow in the soaking water of seeds. Under a scanning electron microscope, we observed that the surface substrates of seeds were removed after soaking for a short time. Infrared spectroscopy revealed that the substrates were mainly composed of saccharides. These findings suggested that the growth of bacterial pathogens during sprouting of seeds depends on the surface saccharides of the seeds.