INTRODUCTION
In recent years the new potential of using micro-organisms
as biotechnological sources of industrially relevant enzymes
has stimulated a renewed interest in the exploration of
extracellular enzymatic activity (EEA) in food-grade yeasts
(Bilinski and Stewart 1990; Burden and Eveleight 1990; De
Mot 1990; Ratledge and Tan 1990). The more extensively
studied yeasts have been those belonging to species of
oenological importance (Rosi et al. 1994; Charoenchai et al.
1997; Strauss et al. 2001), while only a few yeasts of
environmental origin have so far been studied for their
biotechnological value as enzyme producers (Burden and
Eveleight 1990). Although recent surveys have underlined
the potential of unconventional and extreme environments
as a source of natural biodiversity for the isolation and
selection of useful micro-organisms (Bull et al. 1992), to our
knowledge, only the secretion of extracellular proteases has
been studied in yeasts isolated from extreme environments
(Ray et al. 1992; Phaff et al. 1994; Abranches et al. 1997;
Braga et al. 1998).