Novel prebiotics sugars produced by non-conventional yeasts glycosyl hydrolases targeted to specific probiotic species

Trabajo presentado en el 2nd World Congress on Targeting Microbiota, celebrado en París (Francia) del 16 al 17 de octubre de 2014.
In the last decades, the selective sugar metabolism of the gut microbial communities has aroused huge interest. Today, sugars based on fructose (FOS), galactose (GOS) or isomaltose (IMOS) are increasingly being added to food for their beneficia! properties to stimulate the growth and activity of health-promoting Lactobacilli and Bifidobacteria species, the so-called prebiotic effect. Beside sugars hydrolysis, many glycosyl-hydrolases catalyze the transfer of a monosaccharide moiety from the hydrolysed substrate to other carbohydrates, thereby forming horno- and hetero-oligosaccharides with potential new applications in functional food, pharmaceutical and cosmeceutical industry. In that way, sorne fungal ­ fructofuranosidases (-FFases) catalyze the formation of (21) linkages between fructose units (inulin-type 1F­ FOS, e.g. 1-kestose or nystose). We have characterized severa! -FFases with new specificities from yeast such as Xanthophyllomyces dendrorhous, Schwanniomyces occidentalis and Rhodotorula dairenensis . -FFase from X. dendrorhous produces FOS of the 6G-serie (neoFOS, e.g. neokestose and neonystose), that contain a (26) linkage between a fructose and the glucosyl moiety of sucrose1. S. occidentalis -FFase forms 6F-FOS, that include (26)-linked fructose units (with a levan-type structure; e.g. 6-kestose)2 and the enzyme from R. dairenensis synthesizes a complex mixture of 1F-FOS, 6F-FOS and 6G-FOS.3 In addition, we have characterized an a-glucosidase from X. dendrorhous producing IMOS, basically panose (Glc-a(16)-Glc­ a(14)-Glc) instead of the typical mixture of isomaltose/isomaltotriose (1:1) produced by the Aspergillus niger.4 The potential prebiotic activity of sugars synthesized by these enzymes has been evaluated in an in vitro assay developed by Biopolis S.L using different probiotic bacteria! species. 1-Kestose and nystose favour mainly the growth of Lactobacillus plantarum and Bifidobacterium bifidum, respectively; neokestose enhances Enterococcus faecium and to a lesser extent L. plantarum and B. bifidum; panose promotes B. longum and B. catenulatum. lnterestingly, the growth of L. rhamnosus was not substantially improved by any sugars used in this assay and Salmonella typhimurium pathogen was strongly inhibited by 1-kestose.