Dairy factories encounter severe phage predation problems in
routine yoghurt fermentations. Therefore, some of the fast acidifying
S. thermophilus isolates within our isolation set additionally
have been studied for phage resistance to have an indication of
their robustness against phage attacks by Soydemir (2008, pp. 41).
The isolates c95-1, cTY25, cTY55 and cTY63-2 were challenged
against 26 S. thermophilus specific phages that were isolated and
identified from dairy products (Soykut, 2007, pp. 48). Only 5 out of
the 26 phages were reported to be effective on the indicated
S. thermophilus strains. The most phage resistant strain was determined
to be cTY55, for which no plaques were developed for any of
the 26 phages, and the most sensitive strainwas found to be cTY63-
2 showing vulnerability to 5 different phages.