Bifidobacteria are probiotic microorganisms that are widely
used in the food industry. With the aim of using of Petrifilm
Aerobic Count(AC) plates associated with selective culture
media, aliquots of sterile skim milk were inoculated separately
with four commercial cultures of bifidobacteris. These cultures
were plated by both the conventional method and Petrifilm AC,
using the culture media NNLP and ABC. The cultures were
incubated under anaerobiosis at 37 'C for 24, 48 and 72 h. No
significant differences (p>0.05) were observed between the
obtained counts at 48 and 72 h. Bifidobacteria counts in ABC
were usually higher than in NNLP, independent of the plating
method. Subsequently, fermented milk was prepared with a
Streptococcus thermophilus strain, and aliquots were inoculated
with the same bifidobacteria. Then, the fermented milks were
submitted to microbiological analysis for bifidobacteria
enumeration using the same culture media and methodologies
previously described, incubated under anaerobiosis at 37 'C for
48 h. Again, bifidobacteria counts in ABC were higher than in
NNLP, with significant differences for some cultures (p