Effect of fermented soy product on the fecal microbiota of rats fed on a beef‐based animal diet

BACKGROUND: The aim of this study was to determine whether the consumption of soy product fermented with Enterococcus faecium CRL 183, would modify the fecal microbiota of rats fed a diet containing red meat. The rats were placed in groups, distinguished by their diets. For 60 days, group I was given a standard casein‐based rodent feed and groups II–VI, the beef‐based feed. From the 30th day, groups III–VI also ingested the following products: group III, E. faecium ‐fermented soy product; group IV, pure suspension of E. faecium ; group V, sterilized fermented soy product; and group VI, unfermented soy product. RESULTS: Rats that ingested fermented soy product showed a slight increase in the numbers of lactobacilli (0.45 log CFU g −1 ), as did the casein‐based diet group (0.47 log CFU g −1 ). The fermented soy product did not cause any reduction in the number of enterobacteria or clostridia, but promoted a slight fall in the viable count of Bacteroides spp. (2.80 ± 0.20 to 2.34 ± 0.07 log CFU g −1 ). CONCLUSIONS: The results indicate that the ingestion of this fermented soy product did not lead to significant changes in the fecal microbiota of the rats fed on a beef‐based diet. Copyright © 2009 Society of Chemical Industry