Impact of two Erwinia sp. on the response of diverse Pisum sativum genotypes under salt stress

The current study reveals that two non-pathogenic strains of Erwinia sp. are diferent in their PGP traits. By using an integrated approach, a picture of the pea plant status in three genotypes subjected to a salt stress condition was obtained and the role of the two bacterial considered Erwinia sp. strains has been highlighted. Results showed the relevance of plant genotype in determining the response to bacterial inoculants as well as the diferences in the plant mechanisms activated to cope with the stress in the diferent plant/strain combination. Overall, this study emphasizes the importance of understanding the molecular and biochemical processes occurring in plant–microbe interactions at genotype level, and the influence on plant responses to environmental stresses. Further analyses are needed to clarify the behaviour of the three genotypes, such as the leaf water potential, and to verify the efects of the bacterial inoculation in feld conditions, subjectd by an increased environmental unpredictability due to the climate change scenarioCurrently, salinization is impacting more than 50% of arable land, posing a significant challenge to agriculture globally. Salt causes osmotic and ionic stress, determining cell dehydration, ion homeostasis, and metabolic process alteration, thus negatively influencing plant development. A promising sustainable approach to improve plant tolerance to salinity is the use of plant growth-promoting bacteria (PGPB). This work aimed to characterize two bacterial strains, that have been isolated from pea root nodules, initially called PG1 and PG2, and assess their impact on growth, physiological, biochemical, and molecular parameters in three pea genotypes (Merveille de Kelvedon, Lincoln, Meraviglia d'Italia) under salinity. Bacterial strains were molecularly identified, and characterized by in vitro assays to evaluate the plant growth promoting abilities. Both strains were identified as Erwinia sp., demonstrating in vitro biosynthesis of IAA, ACC deaminase activity, as well as the capacity to grow in presence of NaCl and PEG. Considering the inoculation of plants, pea biometric parameters were unaffected by the presence of the bacteria, independently by the considered genotype. Conversely, the three pea genotypes differed in the regulation of antioxidant genes coding for catalase (PsCAT) and superoxide dismutase (PsSOD). The highest proline levels (212.88 μmol g-1) were detected in salt-stressed Lincoln plants inoculated with PG1, along with the up-regulation of PsSOD and PsCAT. Conversely, PG2 inoculation resulted in the lowest proline levels that were observed in Lincoln and Meraviglia d'Italia (35.39 and 23.67 μmol g-1, respectively). Overall, this study highlights the potential of these two strains as beneficial plant growth-promoting bacteria in saline environments, showing that their inoculation modulates responses in pea plants, affecting antioxidant gene expression and proline accumulation

Chemical Composition and Antimicrobial Activity of Essential Oils from Three Mediterranean Plants against Eighteen Pathogenic Bacteria and Fungi

The chemical composition and antimicrobial activity of essential oils (EOs) obtained from three medicinal plants of the Moroccan flora were evaluated. The chemical composition of EOs of Thymus leptobotrys, Laurus nobilis and Syzygium aromaticum was determined using a gas chromatograph coupled with mass spectrometry. Carvacrol (75.05%) was the main constituent of T. leptobotrys EOs, while 1,8-cineole (31.48%) and eugenol (82.16%) were the predominant components of L. nobilis and S. aromaticum EOs, respectively. The antimicrobial activity of the EOs was evaluated qualitatively and quantitatively against 18 microbial strains pathogenic to humans by using the disc diffusion method, and by measuring the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC). The EOs of T. leptobotrys were the most active against the strains tested, with inhibitory zone values ranging from 7.00 to 45.00 mm, and MIC and MMC values ranging from 0.312 to 80.00 mg/mL. In many cases, these EOs exhibited higher antibacterial and antifungal activities than the chemical compounds ciprofloxacin and fluconazole, respectively. This high antimicrobial activity can be ascribed to their richness in carvacrol. The EOs of T. leptobotrys, L. nobilis, and S. aromaticum could be considered a promising alternative to replace chemical antimicrobials, and a readily available natural source of bioactive compounds

Antioxidative and DNA Protective Effects of Bacillomycin D-Like Lipopeptides Produced by B38 Strain

International audienc

Antioxidative and DNA Protective Effects of Bacillomycin D-Like Lipopeptides Produced by B38 Strain

International audienc

Synergistic fungicidal activity of the lipopeptide bacillomycin D with amphotericin B against pathogenic Candida species

In the present study, the synergism of the lipopeptide bacillomycin D in combination with the polyene amphotericin B against pathogenic Candida species is described along with their potential cytotoxicity against mammalian cells. Bacillomycin D inhibited the growth of various Candida species at minimal concentrations from 12.5 to 25 μg ml(-1). Furthermore, it showed a synergistic effect with the antifungal drug amphotericin B in inhibiting the growth of Candida strains, with fractional inhibitory concentration indices ranging from 0.28 to 0.5. Time killing studies revealed a >2-log reduction in the viability of Candida albicans ATCC 10231 cells after 3 h incubation with the combination amphotericin B plus bacillomycin D, at their subinhibitory concentration. Interestingly, when the two drugs were used together at those dosages displaying a synergism in the anti-Candida activity, no cytotoxic effect was observed against mammalian cells. Therefore, the combination bacillomycin D/amphotericin B may represent a valid alternative to conventional antifungals for topical treatment of C. albicans infections. To the best of our knowledge, this is the first report describing the in vitro interaction between the antifungal drug amphotericin B and bacillomycin D against pathogenic Candida specie

Molecular characterization of arbuscular mycorrhizal communities associated with Lathyrus cicera L. grown in northern Tunisia soils

International audienceArbuscular mycorrhizal fungi (AMF) are obligate symbionts that form a mutualistic symbiosis with a wide variety of plant species including legumes. Lathyrus cicera (red pea), is an important annual legume crop cultivated in several drought-prone areas of the world. Limited information is available on AMF diversity associated with red pea and agricultural practices that promote AMF community richness. The article examines the influence of agricultural management practices on AMF species associated with red pea grown in northern Tunisia. Furthermore, we explored AMF communities associated with L. cicera among major soil types in the sub-humid agro-ecosystems of northern Tunisia. The focus was on the effects of environmental factors on the abundance and diversity of AMF communities in rhizospheric soils and root samples. MiSeq amplicon sequencing was used to identify AMF species colonizing the roots and rhizospheric soil of L. cicera. There were 435 amplicon sequence variants (ASVs) identified, representing 25 AMF virtual taxa (VTs) from 5 AMF genera: Glomus >> Claroideoglomus >> Diversipora > Paraglomus > Scutellospora. In summary, agricultural management practices had no impact on AMF colonization in root plants grown in soil under study. The redundancy analysis, however, revealed that soil properties such as salinity, available P and total N have an impact on the distribution and abundance of AMF, especially in Glomus spp