Microbial Profiles of On-line–Procured Sprouting Seeds and Potential Hazards Associated with Enterotoxigenic Bacillus spp. in Homegrown Sprouts†

Abstract

We examined the microbiological quality of sprouting seeds sold through the Internet. Overall, five types of seeds each from six organic and six conventional sources were evaluated. The growth and toxin production of naturally occurring Bacillus spp. in sprouts produced using home-scale sprouting devices also were investigated. For alfalfa, broccoli, lentil, mungbean, and radish seeds, the average microbial counts were 3.3, 4.0, 2.8, 3.5, and 3.6 log CFU/g, presumptive B. cereus counts were 0.7, 1.0, 0.8, 1.0, and 0.9 log CFU/g, and total coliform counts were −0.3, −0.4, −0.5, 0.0, and −0.4 log of the most probable number per gram, respectively. No Salmonella, Escherichia coli O157, other fecal coliforms, or Staphylococcus aureus was found on seeds. Compared with conventional seeds, the organic seeds had lower or equivalent counts for total microorganisms, presumptive B. cereus, and total coliforms. When seeds were sprouting using a glass jar, the growth of presumptive B. cereus was significant for radish and broccoli but not for alfalfa, lentil, and mungbean sprouts; the counts exceeded 5.0 log CFU/g in radish sprouts. When sprouts were grown using an automatic sprouting device, presumptive B. cereus showed slight growth (<3.0 log cycles) in radish, broccoli, and mungbean sprouts but no growth in alfalfa and lentil sprouts. Although the presumptive B. cereus isolates were enterotoxigenic, they did not produce or accumulate detectable levels of diarrheal toxins in freshly produced sprouts.