Antibacterial test using “well diffusion” method
Antibacterial activity test is conducted to find out the potential inhibition ability of isolated lauric acids on the
growth of several bacterial pathogens including S. aureus, B. cereus, S. Thypimurium and E. coli. Sterilization of
materials and tools used in
actibacterial activity test is done prior to the antibacterial experiment. The sterilisation is
done for 30 min in an autoclave at 121°C. Seeding medium of nutrient agar (NA) is prepared by dissolving 20 g of
NA into 1 L of aquades and then heated until all the NA completely dissolved. This medium is then resterilized in
autoclave. Antibacterial activity test is done by incubating NA medium which has been streaked by one loop of test
bacteria at 37°C for 24 h. One loop of bacteria which has been kept for 24 h is put into a test tube containing 9 ml of
sterile physiological sodium chloride and synchronized with the
0.5 MacFarland.
A sterile swab is further inserted
into a test tube, pressed at the walls and scratched homogenously on NA medium.
A pitting with a diameter of 6 mm
is made and kept for several minutes. 100 μL lauric acid with the concentration of 5%, 10%, 15% and 20% are
prepared and added into each pitting. Similar procedures are also done for commercial ciprofloxacin with the
concentration of 0.5% as comparison. After the incubation at 37°C for 24 h, the inhibition zone diameter is
determined by measuring the clear zone formed around the well. This is further taken as inhibitory diameter.