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

Table 4.16 Agar spot test for detection of antagonistic activity
Probiotic candidates Strain
S. aureus ATCC 9144
A. hydrophila ATCC
35654
a :Inhibitory activity expressed as zone of inhibition surrounding the colony in mm
4.7.5 Bile salt hydrolase and β-galactosidase activities
96
Y. enterolitica ATCC
9610
E. sakazakii ATCC
51329
S. flexneri 2a
Chapter IV: Results
S. typhimurium ATCC
19585
L. monocytogenes
ATCC 1911
E. coli 0517:H7
All the candidate probiotic strains were tested for their ability to hydrolyse the sodium salt of
taurodeoxycholic acid. All strains possessed bile salt hydrolase activity (Table 4.17), and in
connection with this, it was noted that all these strains also exhibited high resistance to
duodenum juice containing 0.3% bile salts in the gastrointestinal passage model, which may
be connected with this Bsh activity as suggested by some authors (De Smet et al., 1995; De
Smet et al., 1998; De Boever, 2000). All six strains which were able to grow on lactose as the
sole carbon source tested on this medium were further investigated for β-galactosidase
activity. The highest activity (8.7 μmol/ml/min) was determined for the L. casei LAM-1
strain (Table 4.17). This strain was followed by the reference strain L. plantarum ATCC
8104, which also exhibited a high β-galactosidase activity of 9.3 μmol/ml/min.
L. acidophilus
ATCC 4356
L. plantarum ATCC
8014
L. casei LAM-1 13 10 4 18 6 18 16 13 0 0
LAM-2 10 14 4 19 8 16 18 10 0 0
L. delbrueckii LKH-2 8 6 2 16 6 6 16 8 0 2
LKH-3 6 8 4 16 4 6 17 6 0 0
L. helveticus LKH-5 6 8 4 14 6 6 12 6 0 0
L. fermentum Lamec-29 16 8 6 23 10 12 16 4 2 2