The yeast strains W. anomalus (strain 422) and M. guilliermondii
(strain 443) were cultured in assay tubes with 20 mL of YEPD
medium (10 g/L yeast extract, 20 g/L peptone, 20 g/L glucose) at
28
◦
C for 24 h. Subsequently, the cultures were filtered through a
0.22 m membrane and the cell-free filtrated was used to measure
chitinase and -1,3-glucanase activities.
-1,3-Glucanase (GLU) activity was determined by the rate
of glucose production from the degradation of laminarin
(Sigma–Aldrich) used as substrate (Boller, 1992). Laminarin was
dissolved in ultrapure water (Milli-Q), heated to 60
◦
C for 10 min,
and dialyzed exhaustively against ultrapure water (Milli-Q) for
removal of free glucose. In the assay, 0.1 mL of the sample was
incubated with 0.9 mL of laminarin (2.0 mg/mL) at 50
◦
C for 30 min.
After adding the appropriate reagents to the reaction mixture,
absorbance readings were taken at 520 nm. The quantity of glucose
monomers released was determined using a d-glucose standard
curve (3–30 g/mL). The -1,3-glucanase activity was expressed
in nanokatal per milligram of protein (nkatGlu/mg P). One nkat is
equivalent to 1.0 nmol glucose released/mL/s