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[Display omitted] • L. nobilis essential oil was dominated by 1.8-cineole. • Ethanolic leaves extracts present a higher amount of total phenolics, flavonoids and tannins. • Essential oil and crude extracts showed efficient in vitro acaricidal effect. The current study assayed the toxicity of Laurus nobilis essential oil and crude extracts obtained using solvents of increasing polarity (cyclohexane, acetone and ethanol), on two ectoparasites of veterinary importance, i.e. , Hyalomma scupense and Dermanyssus gallinae. The major components detected in bay laurel essential oil were dominated by 1.8-cineole (46.56 %), α-terpinenyl acetate (13.99 %), sabinene (7.69), α-pinene (5.75), linalool (5.50), methyleugenol (5.36 %) and β-pinene (3.97). The highest total phenolic and flavonoids contents were present in the ethalonic extract of L. nobilis leaves at an amount of 152.88 mg gallic acid equivalents per gram of dry weight (GAE/g DW) and 21.77 mg quercetin equivalent per gram of dry weight (QE/g DW), respectively. In vitro acaricidal effects of essensial oil and crude extract of L. nobilis against H. scupense were ascertained by adult immersion test of engorged females (AIT) and larval packet test (LPT) compared with a reference drug amitraz. The essential oil exhibited strong acaricidal activity against tick engorged female and inhibition of hatching eggs. After 24 h of exposure, at the highest tested concentration (100 mg/mL) essential oil induced 90.67 % mortality of H. scupense larvae (LC 50 = 10.69 mg/mL). Otherwise, essential oil exhibited high acaricidal activity compared to extracts, and among the extract, the ethanolic extract revealed the highest acaricidal efficacy (81.27 % female mortality). Results from mite contact toxicity showed that essential oil and extracts from L. nobilis were toxic to D. gallinae. Bay essential oil was both more toxic to mites, and faster in exerting this toxicity than other tested crude extracts. L. nobilis essential oil concentration leaded to enhance mortality of D. gallinae reaching the highest (100 %) mortality at 12 h with a concentration of 320 mg/mL. While, ethanolic extract acheived this rate after 24 h of exposure at same concentration. Cyclohexanic extract showed weak acaricidal activity. [ABSTRACT FROM AUTHOR]

• Healthy tomato plants harbor diverse endophytic bacteria colonizing mainly leaves. • 36 % of the strains produce antifungal volatiles against Botrytis cinerea. • Antagonistic bacteria belong to 9 Bacillus and 2 Enterobacter species. • Enterobacter volatile and Bacillus soluble compounds reduced B. cinerea infection. • 3-Methylbutan-1-ol reduces postharvest decay of B. cinerea on tomato fruit. Botrytis cinerea is one of the most important postharvest fungal pathogens causing significant losses in fresh fruits, vegetables and ornamentals. Synthetic fungicides are primarily used to control postharvest decay loss, but due to their hazardous use the recent trend is shifting toward safer and more eco-friendly alternatives. The use of antagonistic microorganisms is becoming popular throughout the world. This study investigated the antifungal, the plant growth promoting activities and the identity of volatile organic compounds (VOCs) produced by tomato-derived endophytic bacteria strains. The capacity of selected strains to prevent postharvest B. cinerea infection on tomato fruit through VOCs and soluble compounds was also studied. A collection of 50 bacterial strains was established from different organs of tomato plants sampled from six localities in Cape Bon region (Tunisia). Despite the small geographical scale, complexity and abundance of endophytic communities varied greatly according to the site of origin. Healthy tomato plants harbor diverse endophytic bacteria of Bacillus and Enterobacter genera colonizing mainly leaves with a significant enrichment with Bacillus strains. The in vitro dual culture assays showed that 36 % of the endophytic bacterial strains produce antifungal VOCs against B. cinerea. To our knowledge, this is the first report of VOCs antifungal activity produced by B. nakamurai, B. pseudomycoides, B. proteolyticus, B. thuringiensis, E. asburiae and E. cloacae against B. cinerea. About 14 % of bacterial strains produce VOCs with in vitro specific promoting effects on tomato seedling length or biomass production. The five selected antagonistic endophytic bacterial strains produced a core set of seven VOCs along with different strain-specific and known antifungal VOCs such as 3-Methylbutan-1-ol, sulfur-containing compounds, 2-Heptanone and Dodecanal. Tomato fruit bio-protection assay showed that the Enterobacter strain TR1 produces the most protective VOCs against B. cinerea infection with 3-Methylbutan-1-ol as a major volatile compound which totally suppressed B. cinerea growth and infection on tomato fruit at 0.442 mL L−1 headspace, whereas the Bacillus strains showed better protection against fungal infection when applied as vegetative cells on tomato fruit. These results support the use of the selected strains as potential biocontrol agents to reduce postharvest decay of B. cinerea , as well as 3-Methylbutan-1-ol as promising antifungal volatile to apply during postharvest commercialization of tomato fruit. [ABSTRACT FROM AUTHOR]

Abstract Four hundred and fifty bacteria were evaluated for antagonistic activity against bacterial soft rot of potato caused by Pectobacterium carotovorum sp strain II16. A strain Ar10 exhibiting potent antagonist activity has been identified as Bacillus amyloliquefaciens on the basis of biochemical and molecular characterization. Cell free supernatant showed a broad spectrum of antibacterial activity against human and phytopathogenic bacteria in the range of 10-60 AU/mL. Incubation of P. carotovorum cells with increasing concentrations of the antibacterial compound showed a killing rate of 94.8 and 96% at MIC and 2xMIC respectively. In addition, the antibacterial agent did not exert haemolytic activity at the active concentration and has been preliminary characterized by TLC and GC–MS as a glycolipid compound. Treatment of potato tubers with strain Ar10 for 72 h significantly reduced the severity of disease symptoms (100 and 85.05% reduction of necrosis deep / area and weight loss respectively). The same levels in disease symptoms severity was also recorded following treatment of potato tubers with cell free supernatant for 1 h. Data suggest that protection against potato soft rot disease may be related to glycolipid production by strain Ar10. The present study affords new alternatives for anti- Pectobacterium carotovorum bioactive compounds against the soft rot disease of potato. [ABSTRACT FROM AUTHOR]

• Chemical composition and bioactivities of Eucalyptus essential oils varied significantly between the thirteen species. • 1,8-cineole was the main compound in majority of tested oils. spathulenol was the major one in E. camaldulensis. • Eucalyptus essential oils exhibited a weak antioxidant activity, but a remarkable bacterial inhibition growth. • E. camaldulensis had the strongest bioactivities. The aromatic medicinal plant Eucalyptus and its essential oils have been used since antiquity in folk medicine. The interest in this genus has increased remarkably over the last decade mostly because of their various biological activities. This study aimed to determine the chemical composition of essential oils of thirteen Eucalyptus species leaves and their antioxidant and antibacterial activities. Obtained results showed that E. maidenii had the highest essential oil yield (6.16 ± 1.55 %). Chemical composition (by GC/MS) was highly affected by the species factor (P < 0.001), with the abundance of the major compound 1,8-cineole (82.64 % in E. microcarpa) in most Eucalyptus species. Essential oils exhibited a moderate antioxidant activity, but an interesting bacteriostatic effect against all tested bacteria. Eucalyptus camaldulensis had the strongest bioactivities despite its major compound was spathulenol with efficacy concentration of 50 % EC 50 = 2.96 ± 0.11 mg/mL for the reducing power assay and presented an important inhibition zone (25.33 ± 2.84) and lowest minimum inhibitory concentration (MIC = 0.93 mg/mL) against Serratia marcescens bacteria. This result demonstrated that biological activities could be explained by the synergistic effect between major and minor compounds. [ABSTRACT FROM AUTHOR]