Plant tissue cultures may be contaminated by a wide range of fungi and bacterial species. In order to investigate the effect of Zataria multiflora essential oil to prevent the growth of bacterial contamination on plant tissue culture medium, Z. multiflora essential oil were used at concentrations 100- 1000 ppm in MS medium. Lactobacillus sp. strains are a serious problem in culture medium used in plant tissue culture. The effect of essential oil on bacteria at two concentrations (A: 2 and A: 0.1 – 0.2) separately were analysis. The results showed that the essential oil in 400 ppm concentration increased the rate of bacterial growth inhibition as lowest concentration of bacteria ( A: 0.1- 0.2) and in 700 ppm concentration as highest concentration (A:2). Our result indicates that the use of essential oils could be considered as a practical method for removing contaminants in plant tissue culture procces.
