Combined in situ Physical and ex-situ Biochemical Approaches to Investigate in vitro Deconstruction of Destarched Wheat Bran by Enzymes Cocktail Used in Animal Nutrition.

Marine Deshors,Xavier Cameleyre,Jean Marie Francois,Luc Fillaudeau,Olivier Guais,Virginie Neugnot-Roux

doi:10.3389/fbioe.2019.00158

Abstract

Wheat bran is a foodstuff containing more than 40% of non-starch polysaccharides (NSPs) that are hardly digestible by monogastric animals. Therefore, cocktails enriched of hydrolytic enzymes (termed NSPases) are commonly provided as feed additives in animal nutrition. However, how these enzymes cocktails contribute to NSPs deconstruction remains largely unknown. This question was addressed by employing an original methodology that makes use of a multi-instrumented bioreactor that allows to dynamically monitor enzymes in action and to extract in-situ physical and ex-situ biochemical data from this monitoring. We report here that the deconstruction of destarched wheat bran by an industrial enzymes cocktail termed Rovabio® was entailed by two concurrent events: a particles fragmentation that caused in <2 h a 70% drop of the suspension viscosity and a solubilization that released <30 % of the wheat bran NSPs. Upon longer exposure, the fragmentation of particles continued at a very slow rate without any further solubilization. Contrary to this cocktail, xylanase C alone caused a moderate 25% drop of viscosity and a very weak fragmentation. However, the amount of xylose and arabinose from solubilized sugars after 6 h treatment with this enzyme was similar to that obtained after 2 h with Rovabio®. Altogether, this multi-scale analysis supported the synergistic action of enzymes mixture to readily solubilize complex polysaccharides, and revealed that in spite of the richness and diversity of hydrolytic enzymes in the cocktail, the deconstruction of NSPs in wheat bran was largely incomplete.

Highlights

Wheat is a major energy source in broilers feed worldwide due to its high content of storage polysaccharides
We determined the efficiency of the Rovabio R, a commercial enzymatic cocktail enriched with more than 20 different glycoside hydrolases (Guais et al, 2008) to deconstruct the non-starch polysaccharides (NSPs),which can amount to 46% of wheat bran (Knudsen, 2014)
The purpose of this study was to investigate the mechanism by which Rovabio R, an industrial enzyme cocktail currently used in animal nutrition (Guais et al, 2008), degrades NPSs that are abundantly present in wheat bran

Summary

Introduction

Wheat is a major energy source in broilers feed worldwide due to its high content of storage polysaccharides (i.e., starch; Amerah, 2015). This practice has shown significant beneficial zootechnic effects, such as improving animal performance and reducing excreta by a better nutrient absorption, resulting in a positive environmental impact of animal farming (Fuente et al, 1995; Gunawardana et al, 2010; Lafond et al, 2011a; Lei et al, 2016) While these beneficial effects are assumed to be due to the assimilation of NPSs, there is yet no direct experimental data, at least in the field of feed nutrition, showing how these NSP substrates are deconstructed and solubilized by these enzymes cocktails. There is a need to unravel the mode of action of these cocktails on such complex polysaccharides to eventually improve their efficiency in animal nutrition

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Conclusion