Mmushi T MSc (Microbiology).pdf

3.4. Minimum inhibitory concentrations (MIC) and total activities of the extracts
Quantitative antibacterial activity assay by serial microdilution (Eloff, 1998b) was used
to determine the minimum inhibitory concentration (MIC) of the plant extracts extracted
with hexane, DCM, acetone and methanol. INT was used as an indicator of growth and
the MIC was recorded as the lowest concentration of the plant extract that inhibited the
growth of the test organisms as shown in Table 3.1 and Table 3.2. From the MIC total
activity was calculated and the total activity indicates the degree to which the active
extracts in one gram of the plant material can be diluted with water and still inhibit the
growth of the test organism. Table 3.1. shows the MICs and the corresponding total
activity for all the plant extracts against M. smegmatis. Table 3.2. shows the MICs and
the corresponding total activity for R. erythropolis. On average the acetone extracts had
the lowest MIC values ranging between 0.11- 1.25 mg/ml and 0.08-1.25 mg/ml for M.
smegmatis and R. erythropolis, respectively.
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