Microcalorimetry studies on the antimicrobial actions of volatile oil of dry ginger

The rate of heat output is one of the suitable measurements of metabolic activity of the organism. In this article, microcalorimetry was first applied to study the effect of volatile oil of dry ginger (ginger oil) on Escherichia coli and Staphylococcus aureus growth. The power–time curves were plotted with a TAM air isothermal microcalorimeter. The parameters such as the growth rate constant μ, the peak-time T _p, inhibitory ratio I, and half-inhibitory concentration IC₅₀ were calculated. From the data, the relationships between μ and the concentration of ginger oil c were established. The results revealed that the μ of E. coli and S. aureus both gradually declined with the increase of the c, there were linear relationships between μ and c, and ginger oil had stronger inhibitory effect on S. aureus than on E. coli. Results obtained from our study strongly suggest that microcalorimetry is an ideal method to investigate the effect of drug on microorganism.