Can perfluoroalkyl acids biodegrade in the rumen simulation technique (RUSITEC)?

Area of Science:

• Environmental Chemistry
• Microbiology
• Toxicology

Background:

• Perfluoroalkyl acids (PFAAs) exhibit different behaviors in ruminant tissues compared to monogastric animals.
• The complex rumen microbial ecosystem is hypothesized to influence PFAA behavior.
• Understanding PFAA fate in ruminants is crucial due to their environmental persistence and potential toxicity.

Purpose of the Study:

• To evaluate the hypothesis that rumen microorganisms influence PFAA behavior.
• To assess PFAA recovery using a rumen simulation technique as an indicator of biodegradation.
• To compare PFAA recovery from feed with and without ruminal microorganisms.

Main Methods:

• Rumen simulation technique was employed to study PFAA recovery.
• Fermentation of feed containing PFAAs was conducted in the presence and absence of ruminal microorganisms (MOs).
• PFAA concentrations were measured in feed and fermentation fluid.

Main Results:

• Release of perfluorobutane sulfonic acid (PFBS) from feed was faster than perfluorooctane sulfonic acid (PFOS).
• PFAA recovery in fermentation fluids decreased with increasing chain length for both perfluoroalkyl sulfonic acids (PFSAs) and perfluoroalkyl carboxylic acids (PFCAs).
• Total PFAA recovery was significantly lower in the presence of ruminal MOs compared to sterile conditions.

Conclusions:

• Attachment of MOs to feed particles likely contributes to higher PFAA levels in fermented feed and lower levels in fermentation fluid.
• The significantly lower total PFAA recovery in the presence of MOs suggests microbial interaction.
• Results do not definitively confirm PFAA degradation by ruminal fermentation, despite optimal reductive conditions for MOs.