SELECTION OF HUMAN STRAINS OF BIFIDOBACTERIA FOR THEIR USE IN FERMENTED MILK PREPARATIONS WITH NUTRITIONAL AND THERAPEUTIC ADVANTAGES
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Date
1991
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AAU, Anand
Abstract
Fifty six isolates were obtained from the stools of human infants below the age of four months, by streaking on the plates of Trypticase-Phytone-yeast extract (TPY) medium, incubated under anaerobic conditions. Out of these, thirty two isolates were identified as Bifidobacterium. Three out of 32 strains characterized as Bifidobacterium adolescentis were selected for further study on the basis of their superiority with respect to acid production, resistance to higher concentration of phenol, bile and survival under low pH. Organoleptically acceptable product was one of the criteria in selecting the strains. Accordingly three strains namely; Hbl, Tubl2D and Nub3D were selected and studied with definite objective of using them as dietary adjuncts. The three selected strains showed pleomorphism with bifid, Spatulated, club shaped rods and coccoidal cells. All the three strains were found to grow in milk containing 0.2 per cent phenol, TPY-media with 0.5 per cent bile salts and in media adjusted to pH 5.0. The selected isolates showed medium to high resistance to the antibiotics, known to be used in the intestinal therapy. The strains coagulated skim milk in about 48 h with production of 0.504 to 0.612 per cent titratable acidity and moderate amount of volatile acids containing 120 to 170 µg per litre of acetic acid.
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DAIRY MICROBIOLOGY, A STUDY