2.3.2.3.2. Inhibitory effect of BCA ethyl acetate extract on F. solani
conidia germination. The ethyl acetate partition was prepared from
the filtrate of the more promising BCA (T. atroviridae) upon the
above experiments. The spore germination assay was performed
using the M38-A2 method (CLSI, 2008) with minor modifications.
Briefly, 100 lL of PDB (Sigma Ltd) were distributed in triplicate
in the wells of a 96-wells plate followed by addition of 100 lL of
stock ethyl acetate extract of T. atroviridae at 5.32 mg/mL to the
first well. After thorough mixing, a twofold serial dilution was
achieved by successive transfer of 100 lL into subsequent wells.
Then, 100 lL of F. solani conidia (4 105 conidia/mL) were introduced in the wells containing the test substances. Sterility control
consisted of blank wells without F. solani conidia. Upon incubation
of the plate at 25 ± 2 C for 24 h, an aliquot of culture was taken
from each well and examined microscopically. The percentage of
inhibition was determined according to the formula (4) given
above.
The lowest concentration of ethyl acetate extract exhibiting
100% inhibition of the germination of F. solani conidia was considered as the Minimum Inhibitory Concentration (MIC).