Quantitative procedure for enumeration of bifidobacteria

Area of Science:

• Microbiology
• Environmental Science

Background:

• Bifidobacteria are important gut bacteria found in various environments.
• Accurate enumeration of bifidobacteria in natural aquatic ecosystems is challenging.

Purpose of the Study:

• To develop and validate a novel membrane filter technique for quantifying bifidobacteria in aquatic samples.
• To assess the selectivity and accuracy of the developed method.

Main Methods:

• A selective and differential medium (YN-6) was formulated with specific nutrients and selective agents (nalidixic acid, neomycin sulfate, bromcresol green).
• The technique involved membrane filtration, anaerobic incubation at 37°C for 48 hours, and microscopic examination of characteristic colonies.
• Recovery rates were compared against reinforced clostridial agar using environmental and fecal isolates.

Main Results:

• The YN-6 medium successfully enumerated bifidobacteria with high selectivity and differential capabilities.
• No significant difference in bacterial recovery was observed compared to a standard medium.
• The technique demonstrated low false-positive (<9%) and false-negative (<8%) rates in aquatic and fecal samples.

Conclusions:

• The developed membrane filter technique provides a reliable and accurate method for bifidobacteria enumeration in natural aquatic environments.
• The YN-6 medium is effective for isolating and quantifying bifidobacteria from diverse sample types.
• This method offers a valuable tool for monitoring these important bacteria in environmental studies.