The antifungal activity of essential oils as determined by different screening methods

The existing methods for studying the antimicrobial activity of essential o ils (e.g. the dilution of the test substances in broth or agar medium) are not adequate to evaluate the effects of the volatile components. Growth inh ibition of fungi by various essential oils was determined by direct contact in broth and agar media and compared with the fungistatic action of their vapors using the micro-atmosphere method. Tests were performed on eight cel lulolytic mold strains that often contaminate archive and museum reserves. Thirty-seven essential oils were screened to find the most antifungal ones with potential to be employed as atmospheric preservatives. Chenopodium amb rosioides L. var. anthelminticum, Cymbopogon martinii (Roxb.) W. Watson var , martinii, Cymbopogon nardus (L.) W. Watson var. nardus, Syzygium aromatic um (L.) Merr. et L.. M. Ferry and Pimenta racemosa (Mill.) J.W. Moore were the most active essential oils on the eight strains tested according to dir ect contact methods. C. martinii was inhibitory even after 12 days of incub ation. Using the microatmosphere method, C. nardus and C. martinii volatile s were the most fungistatic, but the vapors of Ch. ambrosioides, S. aromati cum and P. racemosa gave moderate results with a specific short effect of P . racemosa.