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Seminario 18 noviembre Lazaro Hernandez 1920x1080 1

FructoOligoSaccharides (FOSs) are soluble prebiotic fibbers with proven health-promoting effects in humans and animals. Among the traditionally commercialized linear inulin-type FOSs, the sweet-tasting 1–kestotriose (DP3) stimulates the growth of probiotic bacteria faster than 1,1–kestotetraose (DP4) and 1,1,1–kestopentaose (DP5). Not only the DP but also the linkage type appears to influence the efficiency of FOSs fermentation by the gut microbiota. Linear or branched FOSs containing β–(2→6) linkages are claimed to have superior prebiotic properties.
The enzyme sucrose:sucrose 1-fructosyltransferase from Schedonorus arundinaceus (Sa1-SST) produced in the yeast Pichia pastoris displays invariable profiles of inulin–type FOSs when reacts with sucrose at the wide concentration range of 100–800 g/L, being particularly relevant the lack of substrate hydrolysis and the elevated DP3 yield. However, the intrinsic 1–kestotriose hydrolyzing activity of either Sa1-SST or the current fungal biocatalysts demands a strict control of the reaction time to avoid product degradation. The initiation of the fructose peak in HPLC chromatograms indicates the optimal moment to stop the Sa1-SST reaction. At this point, sucrose (600 g/L) is converted into DP3 and DP4, at a ratio 9:1, with their sum representing 55–60 % (w/w) of the total carbohydrates in the reaction mixture. If the reaction proceeds, the use of 1–kestotriose as a fructosyl donor releases free fructose and regenerates sucrose. The presentation will be focused on the development of a bi-enzymatic cascade system that allows, in the same reactor, the complete depletion of the sucrose remaining after the Sa1-SST reaction and the incorporation of branched short-chain FOSs.



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