The M17 Agar is also used for
enumeration of S. thermophilus Besides the M17 agar, ST agar (S. thermophilus
agar) was effective for enumeration of S. thermophilus in the
presence of Lactobacillus delbrueckii subsp. bulgaricus and L. acidophilus
also reported the selectivity of ST agar for enumeration of
S. thermophilus in the presence of L. acidophilus and Bifidobacterium
longum. Both the MRS Agar pH 5.2 and the Reinforced Clostridial
Agar (RCA) pH 5.3 were effective for enumeration of L. delbrueckii
subsp. bulgaricus in the presence of S. thermophilus, L. acidophilus
and Bifidobacterium sp.
Although literature suggests different conditions for selective
enumeration of probiotic microorganisms, the efficiency depends
on several factors including the strain, presence of other cultures in
the product, and type of product to which the probiotics will be
added. Thus, to select the methodology for selective enumeration
of probiotics in dairy products, it is important that different
methods are tested. Given the variety of culture media described in
literature, the aim of this study was to evaluate the effectiveness of
different methodologies for selective enumeration of L. acidophilus
from probiotic yoghurt and Prato cheese.