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Selection of human isolates of Bifidobacteria for their use as probiotics
Mayur R Acharya1, Rajiv K Shah
1Department of Dairy Microbiology, SMC College of Dairy Science, Gujarat Agricultural University, Anand, India.
Insights
Researchers isolated 36 human Bifidobacteria strains from infant fecal samples. The most tolerant strains, Bifidobacterium bifidum and B. breve, demonstrated resistance to digestive tract conditions and are suitable for probiotic applications.
Area of Science:
- Microbiology
- Probiotics
- Infant Nutrition
Background:
- Bifidobacteria are essential gut bacteria, particularly in breast-fed infants.
- Understanding their tolerance to gastrointestinal conditions is crucial for probiotic development.
Purpose of the Study:
- To isolate and characterize human Bifidobacteria strains from infant fecal samples.
- To evaluate the in vitro tolerance of these strains to bile, phenol, and low pH.
- To assess their growth in skim milk as a potential carrier medium.
Main Methods:
- Isolation of 36 Bifidobacteria strains from 15 breast-fed infants (1-6 months).
- In vitro testing for tolerance to varying bile concentrations (1-3%), phenol (0.2-0.4%), and pH (3.0-5.0).
- Evaluation of growth in 10% sterile skim milk, with bifidobacteria counts, pH, and titratable acidity monitored over time.
Main Results:
- All 36 isolates exhibited tolerance to tested pH, bile, and phenol levels.
- All isolates demonstrated good growth in skim milk.
- Bifidobacterium bifidum (isolates 4, 8, 17) and B. breve (isolates 25, 26) showed the highest tolerance to unfavorable conditions.
Conclusions:
- Selected Bifidobacteria strains possess robust tolerance to harsh digestive tract conditions.
- Bifidobacterium bifidum and B. breve are promising candidates for use as probiotic adjuncts in fermented milk and baby food.
- These findings support the development of targeted probiotic formulations for infant health.
Abstract:
An attempt was made to isolate human strains of Bifidobacteria, all together 36, from fecal samples of 15 breast-fed infants ages 1-6 mo. These isolates were checked for their ability to grow in the presence of 1-3% bile, 0.2-0.4% phenol, and low pH (3.0-5.0) in vitro, to evaluate their capacity to grow under hostile and unfavorable conditions of the human digestive tract. Because milk is to be used as a carrier medium, their ability to grow in 10% sterile skim milk was also evaluated. The bifidobacteria count of the cultured milk samples (0, 24, and 48 h) was taken on tryptone yeast extract agar after 48 h of incubation in the presence of 10% CO2 at 37 degrees C. The changes in pH and developed titratable acidity were also recorded up to 96 h of incubation. The results indicated that all the isolates obtained had reasonable resistance to pH, bile, and phenol and were capable of growing well in milk. Among the 36 isolates, Bifidobacterium bifidum (isolates no. 4, 8, and 17) and B. breve (isolates no. 25 and 26) were the most tolerant to unfavorable conditions, and they may therefore be recommended for use in fermented milk or baby food formulations as probiotic dietary adjuncts.