OMNImet®•GUT collection kit supports sample collection and ambient temperature preservation of faecal short chain fatty acids.

Introduction: Short-chain fatty acids (SCFAs) are microbial metabolites that play critical roles in health. As SCFAs are highly volatile molecules and ongoing bacterial metabolism in faecal samples collected can cause compositional shifts, quick SCFA preservation at the point of sample collection is of utmost importance for valid results.

Objectives: This study aimed to evaluate the OMNImet®•GUT kit as an immediate preservation method that stabilises SCFAs at room temperature compared to a standardised laboratory sodium hydroxide method.

Methods: Faecal samples from 12 participants were included. For each sample, 1 g faeces was aliquoted into 2.5 ml OMNImet®•GUT buffer and 1 g faeces was aliquoted into 2.5 ml sodium hydroxide (current laboratory method). SCFA profiles were quantified at zero, 24-, and 48-h using gas chromatography. SCFA profiles were compared across patients, preservation method, and time point.

Results: Results showed that most SCFA profiles were stable and comparable between methods. The sample donor explained the most variance and was the most significant factor associated with the SCFA profiles, independent of the collection kit or duration at room temperature (R² = 0.761, P = 0.001). However, the type of preservation method was also statistically significant (R² = 0.090, P < 0.001). Time did not significantly impact on SCFA profiles up to 48 h (P = 0.582).

Conclusion: These findings support OMNImet®•GUT as a practical alternative for SCFA preservation, particularly for multicentre studies where immediate sample collection can be logistically challenging, but it is important to use a consistent collection method within studies.