Rangées de graines.. © INRA, Elena Schweitzer © Fotolia

Our results

Contents
  1. Introduction
  2. Human milk digestion in the preterm infant: impact of technological treatments
  3. Research & Innovation 2017 - For Food and Biobased Products
  4. The way in which proteins aggregate when heated may change their sensitising potency
  5. Enhancing the viability of spray-dried probiotic bacteria by stimulating their stress tolerance
  6. To stick or not to stick? Pulling pili sheds new light on biofilm formation
  7. When biopolymers selfassemble: a balance between energy and entropy.
  8. Mimicking the gastrointestinal digestion in a lab-on-a-chip:the microdigester
  9. How a milk droplet becomes a powder grain
  10. Research & Innovation 2016 - For Food and Bioproducts
  11. A new process for the biorefining of plants
  12. Under the UV light : the bacterial membrane
  13. Reverse engineering or how to rebuild ... bread!
  14. Green Chemistry: a step towards lipid production in yeast
  15. Individually designed neo-enzymes for antibacterial vaccines
  16. Multi-scale mechanical modelling: from the nanometric scale to the macroscopic properties of bread crumb
  17. Minimill: 500 g to assess the milling value of soft wheats
  18. Microbial production of lipids for energy or chemical purposes
  19. The discrete role of ferulic acid in the assembly of lignified cell wall
  20. Eco-design of composites made from wood co-products
  21. Analysis of volatile compounds enables the authentication of a poultry production system
  22. Nanoparticles as capping agents for biopolymers microscopy
  23. Pasteurisation, UHT, microfiltration...All the processes don't affect the nutritional quality of milk in the same way
  24. Integration of expert knowledge applied to cheese ripening
  25. Controlling cheese mass loss during ripening
  26. The shape memory of starch
  27. Research & Innovation 2015 - For Food & Biobased Products
  28. Behaviour of casein micelles during milk filtering operations
  29. Overaccumulation of lipids by the yeast S. cerevisiae for the production of biokerosine
  30. Sequential ventilation in cheese ripening rooms: 50% electrical energy savings
  31. An innovative process to extract bioactive compounds from wheat
  32. Diffusion weighted MRI: a generic tool for the microimaging of lipids in food matrices
  33. Characterization of a major gene of anthocyanin biosynthesis in grape berry
  34. New enzyme activity detectors made from semi-reflective biopolymer nanolayers
  35. Improving our knowledge about the structure of the casein micelle
  36. Heating milk seems to favour the development of allergy in infants
  37. Fun with Shape
  38. Using volatile metabolites in meat products to detect livestock contamination by environmental micropollutants
  39. SensinMouth, when taste makes sense
  40. A decision support system for the fresh fruit and vegetable chain based on a knowledge engineering approach
  41. SOLEIL casts light on the 3D structure of proteins responsible for the stabilisation of storage lipids in oilseed plants
  42. A close-up view of the multi-scale protein assembly process
  43. Controlling the drying of infant dairy products by taking water-constituent interactions into account
  44. Polysccharide nanocrystals to stabilise pickering emulsions
  45. Discovery of new degradative enzymes of plant polysaccharides in the human intestinal microbiome
  46. A durum wheat flour adapted for the production of traditional baguettes
  47. Virtual modelling to guide the construction of « tailored-made » enzymes
  48. How far can we reduce the salt content of cooked meat products?
  49. Diffusion of organic substances in polymer materials: beyond existing scaling laws
  50. Smart Foams : various ways to destroy foams on demand !
  51. Dates, rich in tannins and yet neither bitter nor astringent
  52. Sodium content reduction in food
  53. Research & Innovation 2014

Discovery of new degradative enzymes of plant polysaccharides in the human intestinal microbiome

Microorganisms play a vital role in the carbon cycle, in particular, by contributing to plant degradation via a perfectly adapted enzymatic apparatus. However, a major obstacle stands in the way of taking advantage of this remarkable enzyme reservoir. In fact, it is estimated that over 95% of the microorganisms present in a large number of ecosystems have never been cultivated and are therefore unknown.

Synthesis pictures illustrating the discovery of new enzyme by functional metagenomy. © inra, Gabrielle VERONESE

Investigating complex ecosystems such as the human intestine

Within this framework, the metagenomic potential is enormous.  This technology, also known as "community genomics", corresponds to the analysis of genomes of all the organisms within a given ecological niche, without any cultivation step.  It has been used in recent years to investigate how complex ecosystems, such as that of the human intestine, function.  Intestinal bacteria play a major role in the maintenance of human health and contribute to nutrition via the metabolisation of undigested food fractions in the upper part of the digestive tract, especially dietary fibres consisting of plant polysaccharides.

Researchers have recently developed a powerful strategy for streamlining metagenome sequencing in order to accelerate the discovery of new enzymes.  This approach was applied to the exploration of the human intestinal metagenome to more effectively understand how bacteria in the digestive tract degrade the plant polysaccharides.

Identifying enzymes with great fiber degradation potential

High-throughtput functional screening of a library of recombinant clones containing fragments of metagenomic DNA, operating at a rate of 200,000 clones per week, made it possible to explore the huge diversity of this ecosystem.  Several hundred clones capable of degrading starch, cellulose, hemicelluloses, pectins and galactan were isolated.  These clones were then submitted to a secondary screening to access their effectiveness for degrading recalcitrant substrates and their stability, in order to isolate the enzymes with the greatest plant biomass degradation potential.  Sequencing efforts were concentrated on 0.84 Mb of metagenomic DNA, corresponding to the 26 most interesting clones.  As a result, 73 polysaccharide degradative enzymes were identified, several of which belonging to new families that have never been characterised.  New multigene systems coding for complementary activities necessary for the deconstruction of complex structures of the plant cell wall were also revealed.

The results allow us to more effectively understand how food fibres are metabolised and with which bacteria, and illustrate the strength of this generic approach for the valorization of the functional diversity of metagenomes.  

Evaluating the effectiveness of these new enzymes to degrade plant biomass

A dual challenge exists in terms of the development of these metagenomic data.  From a generic point of view, we must improve our knowledge of structure-function relationships of these newly identified enzymes at the atomic scale.  From a finalised point of view, the research will initially focus on the effectiveness of these enzymes, alone or in cocktails, to degrade plant biomass.  On the long-term, the aim is to develop a synthetic biology approach based on systems naturally developed by bacteria to adapt to the deconstruction of complex polysaccharide structures.

Fundings

  • ANR 2007-2011 PNRA ALIMINTEST
  • AIP 2008 INRA METAZYMES
  • PhD from the Ministry of Research

Partners

  • AFMB (CNRS Marseille) : B. Cantarel, P. Coutinho, B. Henrissat
  • Micalis (INRA de Jouy-en-Josas) : J. Tap, M. Leclerc, J. Doré
  • Plateforme BioInformatique Genotoul (INRA Toulouse) : C. Klopp
  • LibraGen SA (Toulouse) : P. Robe, R. Nalin

Références

See also

  • Tasse, L., J. Bercovici, S. Pizzut-Serin, P. Robe, J. Tap, C. Klopp, B.L. Cantarel, P.M. Coutinho, B. Henrissat, M. Leclerc, J. Doré, P. Monsan, M. Remaud-Simeon, and G. Potocki-Veronese. 2010. Functional metagenomics to mine the human gut microbiome for dietary fiber catabolic enzymes. Genome Research 20: 1605-1612.