Functional Resilience and Response to a Dietary Additive (Kefir) in Models of Foregut and Hindgut Microbial Fermentation In Vitro.

Gabriel De La Fuente,Charles J Newbold,Eleanor Jones,Shann Jones

doi:10.3389/fmicb.2017.01194

Abstract

Stability in gut ecosystems is an important area of study that impacts on the use of additives and is related with several pathologies. Kefir is a fermented milk drink made with a consortium of yeast and bacteria as a fermentation starter, of which the use as additive in companion and livestock animals has increased in the last few years. To investigate the effect of kefir milk on foregut and hindgut digestive systems, an in vitro approach was followed. Either rumen fluid or horse fecal contents were used as a microbial inoculate and the inclusion of kefir (fresh, autoclaved, or pasteurized) was tested. Gas production over 72 h of incubation was recorded and pH, volatile fatty acids (VFAs), lactate and ammonia concentration as well as lactic acid (LAB) and acetic acid bacteria, and yeast total numbers were also measured. Both direct and indirect (by subtracting their respective blanks) effects were analyzed and a multivariate analysis was performed to compare foregut and hindgut fermentation models. Addition of kefir boosted the fermentation by increasing molar concentration of VFAs and ammonia and shifting the Acetate to Propionate ratio in both models but heat processing techniques like pasteurization or autoclaving influenced the way the kefir is fermented and reacts with the present microbiota. In terms of comparison between both models, the foregut model seems to be less affected by the inclusion of Kefir than the hindgut model. In terms of variability in the response, the hindgut model appeared to be more variable than the foregut model in the way that it reacted indirectly to the addition of different types of kefir.

Highlights

Stability in gut microbial ecosystems is a trait based on the ability of a system to withstand change by minimizing perturbations through the ability of a complex microbiota to perform similar functions and, in time, return to a new equilibrium or the state before perturbation (McCann, 2000)
Analysis of fermentation parameters and kinetics in the foregut model, as well as the concentration of lactic acid bacteria (LAB), acetic acid bacteria (AAB), and yeast are presented in Table 2 and Supplementary Table S2
Addition of kefir prepared in different ways caused an increase in the concentration of total volatile fatty acids (VFAs) after 24 h of incubation, compared to the control (P < 0.05)

Summary

Introduction

Stability in gut microbial ecosystems is a trait based on the ability of a system to withstand change by minimizing perturbations through the ability of a complex microbiota to perform similar functions and, in time, return to a new equilibrium or the state before perturbation (McCann, 2000). It can be defined functional resilience as the way the system responds to the perturbation once it has already happened (Weimer, 2015). Stability can be considered in number of contexts including either; the stability of the microbial a population in terms of the number of microbes and their relative distribution or the functional resilience and response of an ecosystem in terms of fermentation outputs

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