An Investigation of the Correlation of Antibacterial Activity of Thyme (Thymus vulgaris L.) with its Nutrient Elements

Abstract

The present study aimed to examine the correlation of plant nutrient elements with the antibacterial activity of methanol extract of Thymus vulgaris L. grown on soil from the experimental field without application of fertilizers or pesticides on two Gram-positive and two Gram-negative bacteria. The extract of thyme was obtained by maceration of aerial parts of the plant using methanol as the solvent. The contents of macro (P, K, Ca, and Mg) and micro (Fe, Cu, Zn, Mn, and B) nutrients were detected by ICP-OES. The results showed that the macro nutrients were compatible with herbaceous perennial plants, while Fe, Mn and B micro nutrients were high. The methanol extract was significantly effective on inhibiting P. aeruginosa, S. aureus and E. faecalis, while did not inhibit E. coli. The correlation of K and Mg was significantly positive with the growth inhibition of P. aeruginosa suggesting that higher K and Mg contents of the plant would result in higher antibacterial activity against P. aeruginosa, most probably up to a point. On the other hand, significant positive correlation of B was found with the inhibition of both Gram-positive bacteria. In addition, the positive correlation of Ca with the growth inhibition of S. aureus was highly significant. The importance of nutrient contents in medicinal aromatic plants such as thyme was shown with this study. The results therefore imply the conscious and sustainable agriculture of medicinal aromatic plants is crucial for the antibacterial activity of thyme.