Bifidobacterial survival in surface water and implications for microbial source tracking

Area of Science:

• Environmental microbiology
• Water quality assessment
• Microbial source tracking

Background:

• Bifidobacteria inhabit animal and human intestines.
• Sorbitol-fermenting Bifidobacteria (SFB) are indicators of human fecal pollution.
• The total Bifidobacteria (TB) to SFB ratio is a proposed method for differentiating pollution sources.

Purpose of the Study:

• To evaluate the efficacy of the TB:SFB ratio in distinguishing human from animal fecal pollution.
• To assess the stability of the TB:SFB ratio in surface water over time.
• To compare the die-off rates of Bifidobacteria and fecal coliforms in water.

Main Methods:

• SFB detection in sewage and animal fecal samples.
• Calculation of TB:SFB ratios for different sample types.
• Analysis of Bifidobacteria and fecal coliform die-off rates at different temperatures.
• Evaluation of the FC:SFB ratio for determining pollution age.

Main Results:

• SFB were present in all sewage samples and 42% of animal samples (pig, poultry, horse).
• TB:SFB ratios were significantly higher in animal samples (except stored poultry manure) compared to sewage.
• The TB:SFB ratio in sewage remained stable in surface water.
• Bifidobacteria exhibited faster die-off rates than fecal coliforms at 4°C and 22°C.
• The FC:SFB ratio was not suitable for determining sewage pollution age.

Conclusions:

• The TB:SFB ratio is a promising screening tool for identifying human fecal pollution in surface water.
• The ratio's stability in surface water supports its use for source tracking.
• Bifidobacteria die-off kinetics differ from fecal coliforms, impacting their utility as indicators over time.