SCREENING OF ENZYMATIC ACTIVITIES IN NON-SACCHAROMYCES CIDER YEASTS

The activities of polygalacturonase, pectin lyase, beta-glucosidase, beta-xylosidase and protease were determined using solid media in 420 wild non-Saccharomyces cider strains identified by internal transcribed spacer-restriction fragment length polymorphism. The identified species corresponded to Hanseniaspora valbyensis, Hanseniaspora uvarum, Hanseniaspora osmophila, Metschnikowia pulcherrima, Candida parapsilosis and Pichia guilliermondii. The most common activity exhibited was that of beta-glucosidase (33%), with all the analyzed species having some strains able to develop this activity. Strains of M. pulcherrima showed the greatest capacity to produce beta-glucosidase and protease. beta-xylosidase was detected in 17 yeast strains belonging to the genera Hanseniaspora, Pichia and Metschnikowia. All of the tested species have some strains with the capacity to develop beta-xylosidase activity, except for C. parapsilosis. No strains were able to secrete pectin lyase, while polygalacturonase activity was observed in eight Hanseniaspora strains. Only two strains, belonging to the species H. uvarum and M. pulcherrima, developed three enzymatic activities, namely beta-glucosidase, beta-xylosidase and protease.