Thakkar et al.

Results and Discussions

Bile Tolerance

The probiotic cultures are required to work under gastro intestinal

conditions, and hence their tolerance to bile salts is desirable and as a

prerequisite it should be tested in all the candidate strains. The result of

relative bile salts tolerance by all 5 probiotic bacteria are shown in Table 1.

Inȱallȱtheȱcultures,ȱpresenceȱofȱsodiumȱtaurocholateȱasȱbileȱsaltȱdefinitelyȱ

delayed the growth rate. The strain PD2, followed by PH5 was found to

beȱmostȱbileȱtolerantȱasȱtheȱdifferenceȱbetweenȱgrowthȱrateȱinȱtheȱpresenceȱ

and absence of 0.3% bile salt was very less. The strains PFC21 was found

toȱbeȱleastȱbileȱtolerant.ȱTheȱgrowthȱcurveȱofȱallȱfiveȱprobioticȱstrainsȱinȱtheȱ

presence and absence of 0.3% Sodium Taurocholate are demonstrated in

figureȱ1.ȱInȱMRSȱbrothȱwithȱ0.3%ȱbile,ȱPD2ȱshowedȱtheȱbestȱgrowthȱrateȱ

followed by PC27, PH5, PFC21 and PSC6.

Theȱdistinctionȱinȱtheȱbileȱtoleranceȱamongstȱdifferentȱstrainsȱofȱlactobacilliȱ

has been accounted by various researchers (Gilliland and Walker, 1990;

Staley and Bush, 1984). Ashar & Prajapati (1998) tested four strains of

lactobacilli and observed a similar variation with regard to growth in the

normal MRS broth and that containing 0.3% bile salts. Khedkar et al., (1993)

also observed a similar result using three strains of L.acidophilus. Walker

and Gilliland (1993) have found that the ability to grow in the presence

of bile varied among 19 strains tested. Two strains namely ATCC 43121

and 251 grew well than the other strains, while the strain DKW-9 showed

highest sensitivity to bile.

Bile deconjugation ability

Bile salt deconjugation was determined by the amount of cholic acid

released, which ranged from 2.37 to 1.27 mM. Strain PD2 released

maximum amount (2.37 mM) of cholic acid from sodium taurocholate,

followed by PH5, PC27, PFC21 and PSC6 after 24 h of growth at 37ºC. In

a related study by Yang et al., (2008), all lactic acid bacterial strains could

deconjugate sodium taurocholate by liberating cholic acid in the range of

0.98 mM (by L. ruminis La3) to 5.00 mM (by L. plantarum LS12). Our results

also showed similarity with the results shown by Ashar & Prajapati (1998)

and Liong & Shah (2005).

Deconjugation of bile salts release free bile acids which are less soluble

and less likely to be absorbed by human intestinal lumen compared to

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