Abstract

Dried seeds of Monodora myristica were obtained from Oba market in Edo State, ground into fine powder and stored in an air tight plastic container at room temperature until when used. Essential oils were extracted using steam distillation and characterised using the gas chromatography-mass spectroscopy (GC-MS) technique. Microbial isolates obtained from smoke dried fish samples purchased from Oba Market, Benin City, Edo State. Fish samples were put in perforated polythene bags kept in plastic baskets and stored for four (4) weeks. Identification and characterisation of isolates were carried out following standard microbiological procedures. The antimicrobial activity was determined using agar well diffusion method. Data obtained were subjected to a one-way analysis of variance. Significant means were separated using Duncan Multiple Range Test at 95% confidence level. The result showed that M. myristica oil contained twenty-five components which were mainly monoterpene hydrocarbons constituents consisting of limonene (17.6%), α-phellandrene (16.3%), α-pinene (12.2%), β-myrcene (11.2%), 3-Thujene and β-Linalool (7.3%). The oil showed bacteriocidal activity at minimum ihhibitory concentration/minimum bactericidal concentration (MIC/MBC) of 150 mg/mL against Staphylococcus epidermidis PM221, Micrococcus luteus NCTC 2665, Bacillus subtilis 6051-HGW and Pseudomonas aeruginosa AAU2 and fungicidal activity at MIC/minimum fungicidal concentration (MFC) of 300 mg/mL against Aspergillus flavus and Rhizopus species. In view of the aforementioned, the expressed antimicrobial activity is a demonstration of the efficacy of the oil against fish spoilage organism and use in the fishery industry.

Key words: Chemical compositions essential oils, antimicrobial activity, Monodora myristica, agar well diffusion method, Clarias gariepinus.