Evaluating prebiotics – factors affecting microbial metabolism

4 June 2019

Dietary fibre and polyphenols are key plant-based ingredients that enhance the growth of gut microbiota and are associated with improved human health. 

While human intervention studies are ideal for evaluating the prebiotic potential of functional food components, they are expensive and time-consuming, due to the enormous variety and concentrations of foods that could be present for testing. 

In vitro fermentations, using human faecal bacteria, are commonly used to evaluate the prebiotic potential of food ingredients in a rapid first-pass screening protocol. 

However, gut bacteria, even from the same individual, will vary in terms of individual populations and ability to break down the same substrates – due to factors such as diet, antibiotic intake and body weight. This means that gut bacteria in faecal samples collected from the same donor at different time points may not break down the same food in the same biochemical pathway as previous faecal samples. 

This Plant & Food Research study looked at how well a faecal sample can “keep” its bacteria if properly preserved. It is the first longitudinal study (over a duration of three years) to examine the metabolic activity of frozen faecal samples on the consistency of microbial metabolism over multiple batches of experiments. 

The study found that faeces preserved at −80 °C provide a consistent and stable inoculum for performing batch fermentations for a duration of up to three years. 

The study also concluded that multiple factors affect microbial fermentative capacity in human faecal batch culture. Both composition and concentrations of bioactives (dietary fibre, polyphenols) were found to influence the metabolic capacity of human faecal microbiota. 

This information is particularly useful when evaluating the prebiotic potential of foods that vary in the composition and concentrations of fibre and polyphenols – two major components that modulate gut microbiota.

This research received funding from the New Zealand Ministry of Business, Innovation and Employment. 


Journal Reference:

Parkar, S, Davis, P, Trower, T, Hedderley, D, Sutton, K, Ingram, J (2019) Factors affecting microbial metabolism in a human fecal fermentation model to evaluate prebiotics Journal of Nutrition and Intermediary Metabolism DOI: 10.1016/jnim.2018.12.003

Copyright © 2018 The New Zealand Institute for Plant and Food Research Limited