Fate of Escherichia coli O26 in Corn Silage Experimentally Contaminated at Ensiling, at Silo Opening, or after Aerobic Exposure, and Protective Effect of Various Bacterial Inoculants
ABSTRACTShiga toxin-producingEscherichia coli(STEC) strains are responsible for human illness. Ruminants are recognized as a major reservoir of STEC, and animal feeds, such as silages, have been pointed out as a possible vehicle for the spread of STEC. The present study aimed to monitor the fate of pathogenicE. coliO26 strains in corn material experimentally inoculated (105CFU/g) during ensiling, just after silo opening, and after several days of aerobic exposure. The addition of 3 bacterial inoculants,Propionibacteriumsp.,Lactobacillus buchneri, andLeuconostoc mesenteroides(106CFU/g), was evaluated for their abilities to control these pathogens. The results showed thatE. coliO26 could not survive in corn silage 5 days postensiling, and the 3 inoculants tested did not modify the fate of pathogen survival during ensiling. In the case of direct contamination at silo opening,E. coliO26 could be totally eradicated from corn silage previously inoculated withLeuconostoc mesenteroides. The combination of proper ensiling techniques and the utilization of selected bacterial inoculants appears to represent a good strategy to guarantee nutritional qualities of cattle feed while at the same time limiting the entry of pathogenicE. coliinto the epidemiological cycle to improve the microbial safety of the food chain.