Thakkar et al.

Bile Tolerance

Strains of lactobacilli were inoculated @ 2% in 100 ml of MRS and MRSB

(MRS broth containing various concentrations of Sodium Taurocholate)

and incubated at 37ºC.

Every hour, the growth was monitored by

measuringȱtheȱODȱatȱ620ȱnmȱuptoȱ24ȱh.ȱAȱgraphȱwasȱplottedȱofȱA ₆₂₀ nm

versus incubation period and the cultures were compared for their bile

tolerance based on the time required to increase A ₆₂₀

nm by initial 0.3 units

in MRS and MRSB (Gilliland and Walker, 1990).

Table 1. Bile tolerance amongst different strains of lactobacilli inoculated in control

MRS broth

Time taken to increase OD By 0.3 units

(h)

Lactobacilli

Difference (h)

Strains

MRSB (MRS

MRS (Control)

broth + Sodium

Taurocholate)

PD2

3.1

6.7

3.6

PC27

3.2

8.3

5.1

PH5

3.9

8.9

5.0

PSC6

2.8

10.2

7.4

PFC21

4.2

11.8

7.6

Table 2. Deconjugation of sodium taurocholate by lactobacilli

Cholic Acid released

Strains

Sodium Taurocholate ConcmM

PD2

2.378±0.019

PC27

1.780±0.012

PSC6

1.271±0.020

PH5

2.019±0.020

PFC21

1.764±0.014

Bile deconjugation

Bile deconjugation ability was checked by the method of Irvin et al., (1944),

furtherȱ modifiedȱ byȱ Walkerȱ andȱ Gillilandȱ (1993).ȱ Lacticȱ isolatesȱ wereȱ

grown in MRS broth containing 0.2% Sodium thioglycollate and 0.3%

filterȱsterilizedȱconjugatedȱbileȱsaltȱ(SodiumȱTaurocholate)ȱatȱ37°Cȱunderȱ

reduced O ₂ condition in a gas pack jar for 24 h. After incubation, the broth

160