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Democritus University of Thrace (DUTH) 2016

Adaptability of aromatic plants on greek conditions and antimicrobial activity of produced essential oils

Fournomiti, Maria of Nikolaos

Titre : Adaptability of aromatic plants on greek conditions and antimicrobial activity of produced essential oils

Προσαρμοστικότητα αρωματικών φυτών στις ελληνικές συνθήκες και αντιμικροβιακή δράση των παραγόμενων αιθέριων ελαίων

Auteur : Fournomiti, Maria of Nikolaos

Etablissement de soutenance : Democritus University of Thrace (DUTH)

Grade : Doctor of Philosophy (PhD) 2016

Résumé
Four aromatic herbs (oregano, thyme, rosemary and sage) were cultivated in an experimental field (irrigated and non-irrigated) in the Orestiada region for a period of 3 years. Our aim was to study their adaptability and finally assessing the crop yield, the quality of the essential oils as well as their antimicrobial potential, factors that would increase the added value of the finished product.Regarding the development of cultivated plants, oregano and thyme outperform biomass in irrigated than arid farming. During the first two years the irrigated rosemary outweighs unirrigated cultivation and this continues as the plant matures. Irrigated sage performed better than unirrigated only in the October harvests. Essential oils were collected by using the hydro distillation method. The yield of essential oil was 2.1-6.3% for the oregano, 2.2 - 4.1% for rosemary, 1.22-2.55% for thyme and 0.97- 1.58% for the sage. No significant differences were observed between the two cultivation methods at harvest time concerning the yield of essential oils. The analysis of the oils by gas chromatography - mass spectrometry (GC / MS), showed that the major components were carvacrol (73.3-83%) in the oregano, α-pinene (0.8-24.1% ), 1,8-cineole (22.9-26.6%) and camphor (23.8-34.5%) in rosemary, thymol (47.4-60.1%) in thyme and finally 1,8-cineole (12.7-28.5%) and the cis-thugone (5.6-17%) in sage. Finally, we studied the antibacterial activity of the essential oil of each plant against four microbial species Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae and Listeria monocytogenes by using the micro-dilution approach. The minimum inhibitory concentration (MIC) of E.coli was 11.6-231.7 μg / mL for the oregano oil, 212-420.2 μg / mL for rosemary, 24.6-44.8 μg /mL for thyme and 383.7-537.8 μg / mL for sage. The MIC for K. oxytoca was 1-88.4 μg /mL for the oregano, 118-320 μg / mL for rosemary, 4.6-156.9 μg / mL for the thyme and 140-294 μg / mL for the sage. The MIC for K.pneumoniae ranged from 12-98.3 μg / mL for the oregano, 230-390 μg / mL for rosemary, 8.3-33.3 μg / mL for the thyme and 237.3 - 424 μg / mL for the sage. The MIC for L. monocytogenes ranged from 0.5-96 μg / mL for the oregano, 89.6-172.8 μg / mL for rosemary, 0.3-77.6 μg / mL for the thyme and 15.2-460.8 μg / mL for the sage. Of the four plants, the most active essential oil was that of oregano and less that of sage. L. monocytogenes was the least resistant microorganism and E. coli was the most resistant. Based on the above results we could recommend the grown of mainly irrigated perennial oregano in the region. Thyme could only be grown in irrigated perennial crop expecting a good performance in content and quality of essential oil with strong antimicrobial activity. Rosemary it would be better grown in arid permanent planting mainly for its dry biomass and essential oil content but with less antibacterial properties as it matures. Finally, the sage could be grown in irrigated perennials and annuals crops giving better yields concerning the essential oil content during October but with no noticeable activity against microorganisms.

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Page publiée le 29 décembre 2021