In vitro control of potato common scab pathogen bacteria by ginger and laurel essential oils

PRIETO M. C.; QUIROGA P. R.; ASENSIO C.M.; LAMBIR JACOBO A J; LUCINI E.I.; GROSSO N R

Córdoba

Congreso; VII Congreso Internacional de Ciencia y Tecnología de los Alimentos; 2018

Potatoes are recognized as one of the most important food in world nutrition. InArgentina, potato crops are one of main horticultural products. Potato commonscab (PCS) is a worldwide disease that produces damage on tuber surface,getting impact on quality parameters of potato tuber, causing large economicallosses. This disease is mainly produced by S. scabiei, a Gram positivebacterium. At present, crop losses due to this pathogen are still at anunacceptable level in many regions. An alternative control strategy based onessential oils (EOs) could be appropriate. EOs are aromatic oily liquidsobtained from aromatic plants. These natural products are typically composedby complex natural mixtures, and are recognized for their antibacterial,antifungal, antiviral and insecticidal properties. In some published works EOs ofginger (Zingiber officinale R.) and laurel (Laurus nobilis L.) show antimicrobialactivity against some Gram-positive bacteria. The aim of this research was todetermine the antibacterial effect of ginger (Z. officinale) and laurel (L. nobilis)EOs against S. scabiei. Laurel EO was purchased in local market, while GingerEO was obtained by hydrodistillation of roots using a Clavenger-typeapparatus. EOs were analyzed by gas chromatography coupled with massspectrometry (GC/MS). The identification of compounds was performed bycomparison with published data and mass spectra library NIST (2.0). Twobacterial strains of S. scabiei were tested: one strain (M1) was performed byisolation from infected tubers and the other (M2) was obtained from theFacultad de Química, Universidad de la República, Uruguay. Broth dilutionassay was performed to determinate the minimal inhibitory concentration (MIC),using ten serial dilutions of each EO and resazurin as redox indicator. Minimalbactericidal concentration (MBC) of each EO was also determined. The MBCwas considered as the largest dilution without cellular growth. The majorcompound of laurel EO was 1,8-cineole (60.79%) followed by β-terpinil acetate(8.64%), sabinene (7.66%), cis-sabinene hydrate (6.59%) and 1R-α-Pinene(5.78%), while in ginger EO the main compounds were α-citral (30.82%),carveol (20.44%) and camphene (8.90%). The present results suggest thatginger (average values: MIC=0.72 g/L; MBC=0.72 g/L) and laurel (averagevalues: MIC=0.66 g/L; MBC=0.77 g/L) EOs could be considered goodantibacterial agents for both tested strains. These features could be explainedby the presence of α-citral and carveol in ginger, and eucalyptol in laurel, whichare substances that have been recognized for their antimicrobial effects againstsome food borne pathogens. The results of the current indicate that ginger andlaurel EOs are a promising alternative in PCS control. Further research isneeded to evaluate their antibacterial effectiveness in field conditions.