The survival of microorganisms is affected by low pH
of the environment. Hood and Zottola (1988) reported
that L. acidophilus (strain BG2FO4) showed a rapid
decline in numbers at pH 2.0, but at pH 4.0 the number
of viable cells did not decrease significantly. These
results were confirmed by Lankaputhra and Shah
(1995), who concluded that six strains of L. acidophilus
studied, survived well at pH 3.0 or above and the viable
counts remained above 107 cfu mL@1 after 3 h incubation.
Playne (1994), however, reported that L. acidophilus
does not grow well below pH 4.0.