For analysis by the dilution method, solution of the
each compound was prepared, which was then followed
by preparation of a series of 12 dilutions with liquid nutritious
base. The starting solution of the test material
(2.0 mL) was added 2.0 mL of casein soybean digest
broth, thus forming the first dilution. Subsequently, 2.0
mL of this solution was diluted with 2.0 mL casein soybean
digest broth to give the second dilution and so on
until 12 dilutions were obtained. After a 24-hour incubation,
the last tube with no growth of microorganisms was
taken to represent the MIC (minimum inhibitory concentration)
expressed in mg/mL