The influence of natural background flora under aerobic and anaerobic incub
ation on the growth of Escherichia coli O157:H7 in ground beef was investig
ated. The background flora from eight different commercial ground beef were
added to ground beef spiked with E. coli O157:H7 and stored either aerobic
ally or anaerobically at 12 degrees C. The results showed that the presence
of a large number of background bacteria in the ground meat inhibited the
growth of E. coli O157:H7 both aerobically and anaerobically. Inhibition wa
s more pronounced under anaerobic conditions. The background Boras consiste
d mainly of lactic acid bacteria of which approximately 80% were Lactobacil
lus sakei. These results show the importance of the natural background flor
a in meat for inhibition of growth of E. coli O157:H7. (C) 2000 Elsevier Sc
ience B.V. All rights reserved.