Table 3.
In vitro antagonistic activities of the three BCA candidates against Lasiodiplodia theobromae.
| Activities | BCA1 | BCA2 | BCA3 |
|---|---|---|---|
| Production of diffusible metabolites using the cup plate technique (diameter of zone of inhibition measured in mm) | 67.97 ± 0.91 a | 53.82 ± 0.93 b | 0.00 ± 0.00 c |
| Production of diffusible metabolites using the dialysis membrane technique from the fish meal extract agar platesa | + | + | − |
| Production of chitinase using the dialysis membrane technique from the colloidal chitin agar platesa | + | − | + |
| Production of volatile compoundsa | + | − | − |
| Production of hydrogen cyanideb | − | − | − |
| Production of siderophoresb | + | − | − |
| Chitinase from colloidal chitin (U ml−1)c | 5.56 ± 0.17 a | 0.00 ± 0.00 b | 7.75 ± 0.22 c |
| Chitinase from L. theobromae cell wall (U ml−1)c | 3.73 ± 0.14 a | 0.00 ± 0.00 b | 5.60 ± 0.21 c |
| ß-1,3-glucanase from laminarin (U ml−1)d | 3.57 ± 0.16 a | 0.00 ± 0.00 b | 5.54 ± 0.18 c |
| ß-1,3-glucanase from L. theobromae cell wall (U ml−1)d | 2.79 ± 0.20 a | 0.00 ± 0.00 b | 3.76 ± 0.21 c |
a
+, fungicidal effect; −, no fungicidal effect.
b
+, produced; −, not produced.
c
A unit of chitinase was expressed as the amount of the enzyme that released 1 μmol of N-acetyl-D-glucosamine mg−1 protein h−1.
d
A unit of ß-1,3-glucanase was expressed as the amount of the enzyme that released 1 μmol of glucose mg−1 protein h−1.
Values are means of three replicates ± SE. Values with the same letter within a row are not significantly (P > 0.05) different according to Duncan's multiple range test.
BCA1, isolate #12; Streptomyces samsunensis UAE1; BCA2, isolate #29; S. cavourensis UAE1; BCA3, isolate #44; Micromonospora tulbaghiae UAE1.