from indigenous fermented foods and human gut ... - Thapar University

4.7 Probiotic Attributes of Lactobacillus spp.
4.7.1 Survival of Lactobacillus strains under acidic condition
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Chapter IV: Results
Different regions of the gastrointestinal tract have varying acid levels. Stomach and
the regions after stomach have the highest acidity and the pH of these areas may fall as low as
pH 2.0. In order to be used as beneficial adjuncts, Lactobacillus must be able to survive these
harsh conditions and colonise in the gut and therefore tolerant acidity.
Survivals of six different Lactobacillus strains under acidic conditions (pH 2.0) are
illustrated in Table 4.13. In general, the number of survivors of all the cultures during 3 h of
incubation decreased under acidic conditions. The viable count log CFU/ml substantialially
decreased at pH 2.0. LAM-1 showed the highest viability followed by LKH-2, Lamec-29
LKH-5; LAM-2 and LKH-2 had also shown moderate activity at pH 2.0. As shown in Table
4.13 at pH 2.0, LKH-3 had lowest viability.
Table 4.13 Survival of Lactobacillus strains in MRS broth at pH 2.0 at 37°C, as
determined by viable count.
Viable count a (log10 CFU/ml)
Strains 0 h 3 h % inhibition b
LAM-1 9.23 ± 0.07 9.20 ± 0.39 - c
LKH-2 9.71 ± 0.12 6.50 ± 0.47 33.0
LKH-3 9.71 ± 0.08 3.96 ± 0.36 59.2
LKH-5 9.76 ± 0.23 7.79 ± 0.81 20.1
LAM-2 9.56 ± 0.03 7.23 ± 1.12 24.3
Lamec-29 9.25 ± 0.08 7.96 ± 0.04 13.9
a log mean counts of three trials (average ± s.d.); -cno inhibition; n = 3; observations comes from three replicate assays; data are represented
as mean ± sd; b % inhibition = [(cfu/ml initial – cfu/ml final)/ cfu/ml initial] x 100.