Lactic acid (85 – 90%) was obtained from Vetec Química
Fina Ltda. (Rio de Janeiro, Brazil). Stock solutions of the acid
were made in sterile distilled water.
The essential oil from O. vulgare L. (Batch 209) extracted
by hydrodistillation was supplied by Ferquima Ind. e Com.
Ltda. (Vargem Grande Paulista, São Paulo, Brazil). Stock
solutions of the essential oil were prepared in distilled water
added of bacteriological agar (0.15 g.100mL-1) as stabilizing
agent (5). According to Barros et al. (2) the essential oil
assayed here possesses carvacrol (57.71%), p-cymene
(10.91%), terpinene (7.18%) and terpinen-4-ol (6.68%) as its