Antimicrobial activity of essential oils of Thymus vulgaris and Origanum vulgare on phytopathogenic strains isolated from soybean

Abstract

The aim of this work was to study the antimicrobial activity of essential oils obtained from Thymus vulgaris (thyme) and Origanum vulgare (oregano) on phytopathogenic Pseudomonas species isolated from soybean. Strains with characteristics of P. syringae were isolated from leaves of soybean plants with blight symptoms. Ten of these could be identified in Group Ia of LOPAT as P. syringae. Six of these were confirmed as P. syringae using 16S rRNA, indicating the presence of these phytopathogenic bacteria in east and central Argentina. All the phytopathogenic bacteria were re-isolated and identified from the infected plants. MIC values for thyme were 11.5 and 5.7 mg·ml(-1) on P. syringae strains, while oregano showed variability in the inhibitory activity. Both essential oils inhibited all P. syringae strains, with better inhibitory activity than the antibiotic streptomycin. The oils were not bactericidal for all pseudomonads. Both oils contained high carvacrol (29.5% and 19.7%, respectively) and low thymol (1.5%). Natural products obtained from aromatic plants represent potential sources of molecules with biological activity that could be used as new alternatives for the treatment of phytopathogenic bacteria infections.

Inhibitory effect of Thymus vulgaris and Origanum vulgare essential oils on virulence factors of phytopathogenic Pseudomonas syringae strains

“… (‐): Not done; * a From Oliva et al . (); b provided by A. Collmer; c provided by S. Lindow; d provided by Y. Zhao; e provided by D. Studholmer; f provided by L. Gallarato. …”

“…Our group previously reported the inhibitory effect of T. vulgaris and O. vulgare essential oils on phytopathogenic P. syringae isolated from soybean fields (Oliva et al . ). Here, the antimicrobial activity of both oils on P. syringae strains and anti‐biofilm and anti‐phytotoxin effects are reported.…”

“…For P. syringae C13LS, P. syringae EM1, P. syringae LS3, P. syringae Q, P. syringae pv tomato DC 3000, MIC values were obtained from Oliva et al . (). Tubes containing King′s B broth (KBB) were inoculated with each phytopathogenic bacterial strain and incubated at 28 °C overnight.…”

“…A previous study demonstrated the ability of these essential oils to inhibit growth of phytopathogenic P. syringae strains (Oliva et al . ). These results prompted further studies on the mechanism of essential oils against bacterial infection.…”

Anti‐fatigue activity of essential oil from thyme (linalool chemotype) in the polyriboinosinic:polyribocytidylic acid‐induced brain fatigue mouse

“…who reported on the chemical composition, antimicrobial and antioxidant activities of five different Thymus vulgaris L. (Lamiaceae) essential oils, and Oliva et al . who investigated the antimicrobial activity of the essential oils of Thymus vulgaris and Origanum vulgare on the phytopathogenic strains isolated from soybean . On the other hand, only a component analysis research has been reported about thyme (linalool chemotype) …”