Three
Candida oleophila
strains (L06, L07 smooth, and L07 rough) were evaluated
in vivo and
in vitro as biocontrol agents against
Penicillium expansum
on postharvest ‘Golden Delicious’ apples (
Malus domestica
Borkh.) in Chihuahua, Mexico. The
in vivo and
in vitro activity of exo-β-1,3-glucanase was measured as a possible biocontrol mode of action for
C. oleophila. Mean disease incidence caused by
P. expansum was 0.3% for apples treated with fludioxonil + ciprodinil, which were used as a positive control, and 1% for fruits treated with a combination of the three
C. oleophila strains; the effects of these treatments were significantly equivalent. Disease incidence in control apples was 39% and was significantly different from the other treatments. The
in vivo exo-β-1,3-glucanase activity began at 24 h and peaked at 72 and 96 h for all treatments. Strain L06 had the highest activity (7.96 nKat) and a specific activity of 2.92 nKat μg
-1.
Candida albicans
had the lowest activity (2.83 nKat) and a specific activity of 0.67 nKat μg
-1. The highest
in vitro activity was for
C. albicans (85.03 nKat) and the lowest for strain L06 (78.2 nKat). Significant differences in both
in vivo and
in vitro enzymatic activity were observed between strain L06 and
C. albicans. Polynomial regression analysis (R
2 = 0.96
in vitro and 0.68
in vivo) indicated that increased enzymatic activity was associated with reduced fruit disease incidence. The production of exo-β-1,3-glucanase by
C. oleophila is a possible mode of action for the efficient biocontrol of
P. expansum on postharvest apples.