Probiotic activity of Bifidobacteria from infant faeces

Abstract

In the present study four isolates belonging to three bifidobacterial species with probiotic properties were isolated and identified from the faeces of breast fed infants and incorporated in the preparation of a nutraceutical whey based malt food. Identification of isolates to the genus Bifidobacteria was based on phenotypic characteristics like the unique pleomorphic morphology and carbohydrate fermentation profile. Molecular tools like 16S rRNA targeted genus and species specific mPCR were used for confirmation. The four isolates (of 3 species) identified wereB. longum(IB10 and IB12)B. breve (IB39)and B.bifidum (IB42). The nucleotide sequences of the identified species were submitted to the GenBank for acquisition of accession number. The identified species were screened for probiotic properties like bile tolerance, antimicrobial activity and tolerance to acidity. All the four isolates showed more than 80 per cent viability in the presence of 0.4, 0.8 and 1 per cent of bile salt. IsolateB.longum (IB10)showed maximum antimicrobial activity against Bacillus cereus (zi3.03 ± 0.019 mm), Staphylococcus aureus (zi3.00 ± 0.031mm), Escherichia coli(zi2.98 ± 0.043 mm) and Pseudomonas aeruginosa (zi3.03 ± 0.051 mm) in the cell free supernatant. All the four bifidobacterial isolatesshowed more than 80 per centviability atpH 3.B.longum (IB10)was a better probiotic when compared to other isolates as it had maximum antimicrobial activity and tolerance to bile and acidity.