2.2. Yeast strains
The Cicy-Ki yeast was isolated from the base of the henequen
leaf following classical microbiological procedures and was then
characterized by phenotypical and molecular tests (Pérez-Brito
et al., 2007). The yeast S. cerevisiae was obtained in a commercial
store (Safoeno brand from Safmex S.A. de C.V., México). Both yeasts
were cultivated in Petri dishes, in YPGA medium containing: glucose
(20 g L1), yeast extract (5 g L1), peptone (10 g L1) and agar
(20 g L1) and incubated at 35 ± 2 C in darkness. The cultures were
collected in sterile water and kept at 4 C until their use. The concentration
and viability of the cellular suspensions were measured
(by staining with methylene blue).