The present studies are carried out to elucidate the following; Effect of heat on the activity of the Enterococcus spp. isolates and Escherichia coli Nissle 1917  in the presence of lactulose and apple and orange extracts. During the course of examination the activity of certain specie of bacteria, namely Enterococcus molodoratus, Enterococcus faecles, Enterococcus faecium and Eschericia coili nissilewere examined for their activity at 55, 60 and 65°C.durin the incubation for different times. Rsults revealed wide variation according to the tested organism, temperature and the exposure time. For the enumeration of the examined cultures, the Mac Konkey agar No.3 was used for the Escherichia  coli, and tryptone soy agar was used for the Entreococcus spp.  Survival of the examined strains were tested at 55, 60, 65°C.