Behavior of enteroaggregative Escherichia coli, non-O157-shiga toxin-producing E. coli, enteroinvasive E. coli, enteropathogenic E. coli and enterotoxigenic E. coli strains on mung bean seeds and sprout

The behavior of enteroaggregative Escherichia coli (EAEC), non-O157 shiga toxin-producing E. coli (non-O157-STEC), enteroinvasive E. coli (EIEC), enterotoxigenic E. coli (ETEC) and enteropathogenic E. coli (EPEC) on mung bean seeds at 25 ± 2 °C and during germination and sprouting of mung bean seeds at 20 ± 2° and 30 ± 2 °C and on mung bean sprouts at 3 ± 2 °C was determined. When mung bean seeds were inoculated with EAEC, non-O157 STEC, EIEC, EPEC or ETEC strains, all these diarrheagenic E. coli pathotypes (DEPs) survived at least 90 days on mung bean seeds at 25 ± 2 °C. All DEPs grew during germination and sprouting of seeds, reaching counts of approximately 5 Log and 7 Log CFU/g after 2 days at 20 ± 2° and 30 ± 2 °C, respectively. However, when the sprouts were inoculated after 1 day of seeds germination and stored at 20 ± 2° or 30 ± 2 °C, no growth was observed for any DEPs during sprouting at 20 ± 2 °C per 9 d; however, a significant increase in the concentration of DEPs of approximately 0.7 log CFU/g was observed during sprouting at 30 ± 2 °C after 1 day of sprout contamination. Refrigeration reduced the number of viable DEPs strains on sprouts after 10 days in storage; nevertheless, these decreases have no practical significance in the safety of the sprouts.