In vitro evaluation of essential oils for potential antibacterial effects against Xylella fastidiosa

Abstract

The main pathogen underlying citrus variegated chlorosis (CVC), a citrus fruit disease, is Xylella fastidiosa, a Gram‐negative s‐shaped bacterium that blocks water and nutrient circulation. Discovering new pesticides to combat CVC have become a challenge. Research into essential oils (EOs) is crucial because these substances can be potentially useful in pest control. This study aims to determine minimum inhibitory concentrations (MIC), to investigate biofilm inhibition capacities through MBIC50 analysis, and to evaluate synergistic effects with streptomycin of 17 EOs against X. fastidiosa. This study also analyses the chemical profiles of the EOs that provided the best antibacterial activity results. The MIC values of the EOs ranged from 125 to 1,000 µg/ml. Analysis of the MICB50 values of the sandalwood and patchouli EOs revealed biofilm inhibitory activity. No synergistic effects were evident for streptomycin combined with the sandalwood or patchouli EOs: ΣFIC was 1.25 and 1.5, respectively, which denoted indifference. We detected α‐gurjunene (27.6%), patchouli alcohol (21.6%), α‐bulsene (17.3%) and α‐patchoulene (6.3%) as the major patchouli EO constituents. On the basis of our results, the sandalwood and patchouli EOs present antibacterial action and are promising natural sources for the development of new pesticides against X. fastidiosa.

Chemical composition and biological activities of essential oil from flowers of Psidium guajava (Myrtaceae)

“…Results showed that PG-EO exhibited high in vitro antibacterial activity against X. fastidiosa (MIC = 12.5 µg/mL) and P. carotovorum (MIC = 62.5 µg/mL) and may have promising activity against phytopathogenic bacteria. It should be highlighted that PG-EO exhibited more promising in vitro anti-Xyllela fastidiosa activity than the ones of seventeen essential oils whose MIC values had already been reported by the literature (Santiago et al, 2018). In addition, essential oil from P. guajava leaves has already been described as a natural product which has potential activity against Sclerotinia sclerotiorum, a phytopathogen that also causes damage to agriculture (Silva et al, 2018).…”

Screening and identification of BP100 peptide conjugates active against Xylella fastidiosa using a viability-qPCR method

“…The difficulties in managing diseases caused by Xf have stimulated the search for novel bactericides. Several antimicrobial compounds, such as toxins, antibiotics, phenolic acids and AMPs, have been reported to be active against several Xf strains with MBC or minimal inhibitory concentrations (MIC) ranging from 8 to 800 μM [14,15,[41][42][43][44]. Interestingly, the AMPs magainin I and II, and dermaseptin have been reported to display low MIC or MBC values against Xf [14].…”

Essential Oils as Antimicrobials in Crop Protection

“…Table 1 shows a compilation of research articles [ 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ] in which different plants/essential oils were analyzed by their possible antibacterial activity that can affect both crops and stored products, among others. This table contains part of the experimental work developed by the researchers (for a better understanding, consult the original sources).…”