Spectrophotometric Studies of the Antibacterial Activities of Crude Extract from Cocoa Pods Infected with Phytophthora palmivora

Aim: To study antibacterial activities of the dichloromethane extract of cocoa pods infected with P. palmivora on selected bacteria pathogens using paper disc bioassay technique, agar diffusion techniques and spectrophotometric methods.

Place and Duration of Study: Department of Microbiology, Ekiti State University, Ado Ekiti, (formerly University of Ado Ekiti) Nigeria, between January and July, 2010.

Methodology: The crude extract of cocoa pods infected with Phytophthora palmivora was extracted using dichloromethane. The extract was concentrated using rotary evaporator at 40°C and stored at 4°C. Selected bacteria isolates pathogenic to plants and human were obtained from International Institute for Tropical Agriculture (IITA) and Ekiti State University Teaching Hospital, Ado Ekiti, Nigeria respectively. The antibacterial study was carried with different concentrations of the extracts 50, 100, 150 and 200 mg/ml using spectrophometric methods, paper disc and agar diffusion techniques.

Results: The results of the antibacterial activity using paper disc method showed that Xanthomonas sp. (Cp) was highly susceptible to the extract with highest zone of inhibition followed by Bacillus sp. (R). E. coli, Shigella sp., Pseudomonas sp (R) and Xanthomonas sp (R) had no zone of inhibition. The results of the antibacterial activity using agar diffusion method showed that Xanthomonas sp. (Cp) and Bacillus sp. (R) were highly susceptible to the induced extract with the highest the zone of inhibition followed by E. coli, Shigella sp., Pseudomonas sp. (R) and Xanthomonas sp. (R). The result of the antibacterial activity using spectrophotometric method showed that Xanthomonas sp (R), Xanthomonas sp (Cp), Pseudomonas sp. (R), Bacillus sp (R), E. coli and Shigella sp were highly susceptible to the extract at different concentrations.

Conclusion: This present study showed that extract from infected cocoa pods can serve as a good source of antibacterial agent. Further works should be carried out to purify and determine the structures of the active compounds.