Evaluation of antimicrobial activity of ginger extracts (oil, juice and starch) on selected microorganisms

Ginger (Zingiber Officinale) has been traditionally used for its medicinal properties. It possesses a noticeable antimicrobial activity against most microorganisms. This study evaluated the antimicrobial properties of ginger oil, juice and starch, in order to establish their antimicrobial potentials. Different parts of the ginger rhizome were extracted (oil, juice and starch), and cultures of Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhi, Candida albicans and Aspergillus niger were used to evaluate the antimicrobial capacity of the ginger imploring the Agar-Well Diffusion Assay method. The physicochemical properties, proximate composition and characterization of ginger were also determined using standard methods.  The ginger extracts showed a noticeable antimicrobial activity which  was  confirmed by checking the susceptibility of different strains  of bacteria  and fungi  by measuring  the zone  of inhibition. The result of zone of inhibition measured were as follows; at 100 concentration Staphylococcus aureus had 19.6mm, Bacillus subtilis 9.3mm, Salmonella typhi 4.3mm, Escherichia coli 21.3mm while Pseudomonas aeruginosa and Candida albicans had 4.6mm respectively. The ginger starch/powder did not show any effect on the test organisms. It was only the ginger oil that showed significant effects against the test organisms except Aspergillus niger. The proximate composition of the ginger was found to be moisture content 47.80 ± 0.44, fat/lipids 19.30± 0.82, crude protein 3.71 ± 0, Ash 6.27 ± 0.15, crude fibre 7.22 ± 0.029 and carbohydrate 15.83 ± 1.01. The ginger oil was found to have the following properties: P^H 5.3± 0.26, Specific gravity 0.593 ± 0.11, Refractive index 0.239± 0.08, Acid value mgKOH/g 1.81 ± 1.35, saponification value mgKOH/g 30.77 ± 5.1 and iodine value mg/g 3.156 ± 0.89. In this study, it was established that the oil extract exhibited a very high antimicrobial potential due to its manifestation on six out of the seven isolates used, with E. coli being highly inhibited. This implies that ginger oil is effective in the treatment of infections caused by the six test organisms.