Analysis of antimicrobial activity by defence fluid of Coptotermes Curvignathus on selected wood microbes

The foraging ability of subterranean termites in microbe-rich environment was reported to contribute and push forward for evolution of termite' inner defence mechanisms. However, there are limited information about termite defence fluid resistance and inhibition against microbes. In peninsular Malaysia, currently there is no study done on defence fluid of Coptotermes curvignathus Holmgren and hence this will be the first study on interaction of C. curvignathus and microbes colonizing in its habitat. One gram positive (CCN 6) and one gram negative (CCN 2) bacteria were isolated from nest of C. curvignathus selected as test microbes. Escherichia coli and Bacillus subtilis were selected as screening microbes also. Crude extract of C. curvignathus was diluted to 0.5mg/ml, 1.0mg/ml, 5.0mg/m1 and 10.0mg/m1 to identify Minimum Inhibitory Concentration (MIC). Disk diffusion assay was applied by placing disks of C. curvignathus crude extract on agar plate spread selected bacteria. Measurement of inhibition zone and statistical analysis were done to determine antimicrobial activity of C. curvignathus crude extract. Based on the result, the antimicrobial activity increases when the concentration of C. curvignathus crude extract increases. The minimum inhibitory concentration is different on different type of bacteria. Gram positive bacteria is less susceptible to C. curvignathus crude extract compare to Gram negative bacteria. The average inhibition zone of CCN 2 is 3.2mm ± 1.86 while average inhibition zone of CCN 6 is 1.0mm ± 1.38. The average inhibition zone of E. coli is 2.9mm ± 1.55 while average inhibition zone of B. subtilis is 2.2mm ± 1.13. Moreover, there is no significant difference between antimicrobial activity of C. curvignathus crude extract and antibiotic disks (Gentamicin). Therefore, it is concluded that C. curvignathus crude extract has similar antimicrobial effectiveness as antibiotic. This study can be preliminary reference for any further research on antimicrobial properties of termites defence fluid.