BioMatNet Item: FAIR-CT97-3811 - Development of xylo-oligosaccharides and xylitol for use in pharmaceutical and food industries (XYLOPHONE)

FAIR-CT97-3811
Development of xylo-oligosaccharides and xylitol for use in pharmaceutical and food industries (XYLOPHONE)

Contacts
Further Information

	Type of Project	Shared Cost
	Contract No	FAIR-CT97-3811
	Total Cost	1,250,760 ECU
	EC Contribution	850,000 ECU
	Start Date	01/05/1998
	Duration	36 Months

Objectives

The present project has the general aims:

Optimise selective processes for lignocellulosic wastes fractionation using hydrothermal-based treatments producing crude xylo-oligosaccharides syrups
Purify different xylo-oligosaccharides as intermediate or end products for pharmaceutical and food applications
Resolve the structure of novel oligosaccharides with biological activity obtained from lignocellulosic wastes
Obtaining of a fast xylo-oligosaccharide degrading recombinant Debaryomyces hansenii
Optimisation of the fermentation of xylo-oligosaccharides-based and xylose-based media for xylitol production in batch reactors using wild and recombinant yeast strains
Feasibility of novel industrial processes for oligosaccharide and xylitol production: technical and economical considerations

Technical Approach

In this proposal we will study the processing of plant raw materials, such as agro-industrial, agricultural and forest wastes into higher added-value final or intermediate products by using physical, chemical and biotechnological processes. Hemicellulose-rich plant wastes will be fractionated by physical treatments minimising the environmental impact (avoiding acid, alkali or organosolv additions) to selectively release the xylan fraction, from the remaining plant biomass. The goal is to optimise an integrated process for biomass fractionation that can be used for different biomass wastes producing low calorie food ingredients (xylitol) and xylo-oligosaccharides, the latter as intermediate products for pharmaceutical and food applications. The xylo-oligosaccharides will be extensively purified, structurally characterised and their biological activity as anti-inflammatory or anti-tumour agent will be quantified.

Xylo-oligosaccharide syrups will be obtained by optimising different hydrothermal treatments, depending of the raw material. A user-friendly format model will be developed for process assessment. The xylo-oligosaccharide mixtures will be separated and isolated by preparative size exclusion (HPAEC) chromatography. Structural analysis to identify the range of substituted oligosaccharides carrying a residual arabinose, acetyl or 4-0-methylglucuronic substituent will be subject of study digesting the oligosaccharides with pure and well characterised enzymes. For both pharmaceutical and food industrial applications, we foresee to focus the research on oligosaccharides, mainly from DP range of 2-7. One of the partners (a SME company) will focus its research efforts to develop application technologies for some of the xylo-oligosaccharides as additive for healthier foods.

Alternatively, crude xylo-oligosaccharide syrups will be used as fermentation media for xylitol production. As wild yeast strains do not easily use oligosaccharides as C-source but only after hydrolysis to monosaccharides, the cloning of the b-xylanase, b-xylosidase and a-L-arabinofuranosidase genes from fungi into Debaryomyces hansenii will be carried out in order to produce directly xylitol from xylo- or arabino-xylo-oligosaccharides. Another approach will be the engineering of Saccharomyces cerevisiae to add the above genes plus the xylose reductase gene for xylitol production.

Results To Date

The experimental work in the first six months was directed towards a detailed characterisation of the four raw materials (corn cobs, wheat bran, brewery's spent grains and Eucalyptus wood biomass) . In addition to composition analysis, isolated cell wall materials were fractioned by sequential extraction using hot water and alkali resulting in two (glucuronoarabino) xylan fractions leaving a cellulose-rich residue. All fractions were digested with pure enzymes and the degradation was monitored using HPSEC, HPAEC and MALDITOF MS.

In addition, the hydrothermal operational conditions leading to a maximum oligomer concentration and their distribution of molecular weights are being carried out simultaneously in three European countries. The molecular genetic work towards the construction of an oligosaccharide-degrading yeast strain has started.

Contacts

Coordinator

Francisco M F GIRIO / INETI PORTUGAL

EC Scientific Officer

Ciarán MANGAN / European Commission - DG Research Quality of Life Programme - Unit B1.2 / BELGIUM

Participant