Seasonal Evaluation Of The Antibacterial Activity Of Rosemary Essential Oil (Rosmarinus Officinalis L.) In A SemiArid Region (Djelfa)

Abstract

The objective of this study was to evaluate the yield and antibacterial activity of essential oils from rosemary leaves (Rosmarinus officinalis L.) collected in the semi-arid region of Djelfa, Algeria, against three bacterial strains over different seasons. Essential oils were extracted by hydrodistillation. The antibacterial activity was tested using the disk diffusion method against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Oil yields were 0.7% in autumn, 0.2% in winter, 1.04% in spring, and 1.90% in summer. All tested bacterial strains were sensitive to rosemary essential oil in most seasons, but with variability depending on the strain and season. The findings highlight seasonal variation as a determining factor for both yield and antibacterial efficacy of rosemary essential oil.