ABSTRACT

The increase of microbial resistance to conventional antimicrobial agents such as antibiotic

creates a need to find new antimicrobial source especially substances from natural origin.

Recently, exploration of effective antimicrobial compound from plants has been intensified.

Most plants are medicinally useful in treating human diseases. The aim of this work was to

investigate the antibacterial activity of cashew nut oil and time kill kinetics on some coliform;

Klebsiella species, Pseudomonas spp, Escherichia coli and Shigella spp. The nuts were washed

in cold water to remove dirt adhering to the surface. After washing, manual separation of the

husk from the nuts was done. The method of choice for the extraction of the plant oils was screw

press method. The oil yield of the cashew seeds, as extracted, was high and this imply that the

seed is an oil seed and will be a good source of oil as a raw nurtured for industrial and other

uses. Agar well diffusion assay was employed to determine the antibacterial activity of cashew

nut oil by measuring the diameter of zones of inhibition around the tested organisms. The results

shows that commercial antibiotic (Ampicillin) was used as the control. There were variations in

the activity of the oil against the different coliforms with inhibition diameters ranging from

11.33mm to 14.00mm. The oil was most active against Pseudomonas spp (14.00mm) and

showed least activity against shigella spp. The antibacterial activity was demonstrated in the

form of increasing potency of shigella spp (11.33), klebsiella spp and E.coli (13.67mm each) and

Pseudomonas spp (14.00mm). From the result the MIC of cashew nut oil on Klebsiella species

and Pseudomonas spp were 40mg/ml and 20mg/ml respectively and on Escherichia coli and

Shigella spp were 20mg/ml and lOmg/ml respectively (Table 4.4 and 4.5). From this study, it

was observed that cashew nut oil extracts exhibited better MIC on the test organisms. The time

killed kinetic was show in Figure 4.1, 4. 2, 4.3 and 4. 4. There were variation in the levels of

retardation of the growth of the coliform by the oil extract. There was a mediation ranging from

1.67><107cfu/g to 6.88><106cfu/g after 2hrs and ultimately to 6.12xl06cfu/g after 8hrs of

incubation by klebsiella species isolate after heat with one-half MIC concentration oil extract.

The growth of klebsiella species after 8hrs of incubation with oil extract were 1.67xl07cfu/g to

6.12xl06cfu/g at oil concentrations. Similar radiation were recorded in the retardation of froths

of E. coli, Shigella species and Pseudomonas spp by the oil extract at the three concentrations

repeatedly.