We have purified a fructosyltransferase from Aspergillus aculeatus present in commercial samples of Pectinex Ultra SP-L. We have also isolated and purified extracellular beta-fructofuranosidases from cultures of the yeasts Xanthophyllomyces dendrorhous (formerly Phaffia rhodozyma, Schwanniomyces occidentalis and Rhodotorula gracilis. The transferase activity of these enzymes was analysed in detail, along with that of beta-fructofuranosidase from Saccharomyces cerevisiae. Interestingly, the maximum FOS yield (expressed as weight percentage of the total amount of carbohydrates in the mixture) was significantly higher with the enzyme from A. aculeatus (61%), compared with those from X. dendrorhous, S. occidentalis and R. gracilis (17-19 %), and that from S. cerevisiae (8%). In addition, significant differences were encountered in the selectivity of the process: A. aculeatus synthesized only 1F-FOS, X. dendrorhous formed basically neo-kestose, whereas S. occidentalis and S. cerevisiae were selective towards the production of 6-kestose. R. gracilis synthesized a complex mixture of di-, tri- and tetrasaccharides.

This work was supported by a grant from the Spanish Ministry of Education and Science (BIO2004-03773-C04), by Genoma España (the National Foundation for Promoting Genomics and Proteomics), and by an institutional grant from the Fundación Ramón Areces to the Centro de Biología Molecular Severo Ochoa

Peer reviewed