Browsing by Author "Djemouai, Nadjette"

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    Actinobacteria: an underestimated source of potential microbial biocontrol agents against fusarium-related diseases in cultivated crops
    (Springer, 2023-07-28) Djemouai, Nadjette; Meklat, Atika; Yekkour, Amine; Verheecke-Vaessen, Carol
    Crop infections with Fusarium spp. and associated mycotoxins have devastating economic implications and are a significant limitation to fifteen of the seventeen United Nations Sustainable Development Goals. Therefore, it is necessary to develop innovative strategies to reduce or eliminate diseases caused by Fusarium spp. in cultivated crops. Management of Fusarium-related diseases using beneficial microorganisms is a promising and eco-friendly solution. In this context, actinobacteria are considered one of the best candidates because of their multifunctional properties, which consist in the reduction of Fusarium spp. diseases and the promotion of plant growth. Actinobacteria represent a large Gram-positive bacterial phylum that is widespread in different environments, especially in soil. They are principally known for their versatile capacity to produce biologically active molecules with potential applications in different fields, including agriculture. As Fusarium species threaten diverse crops worldwide and cause global yield and quality losses that can negatively impact food security, the use of actinobacteria for plant diseases management is gaining interest as a safer and more potent alternative to ineffective synthetic-based pesticides. Thus, this work aims to review and highlight the importance of actinobacteria as microbial biocontrol agents and discuss the current research on Fusarium spp. diseases with a focus on species that threaten economically important crops, such as F. graminearum, F. oxysporum, F. solani, and F. culmorum. This review also presents actinobacteria-based products that have been patented for Fusarium disease control. We aim to provide valuable data, guidance and advancements for future research on microbial biocontrol against Fusarium-related diseases. In addition, this review emphasizes the need for further research about the impact of actinobacteria-Fusarium interactions on mycotoxin production. It also highlights the need of in-depth understanding microbial biocontrol mechanisms to ensure safe and sustainable crop production worldwide.
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    Biological activities of Streptomyces sp. Bts40 isolated from the rhizosphere of Artemisia herba-alba Asso
    (Universitatea din Oradea, 2022-01-04) Djemouai, Nadjette; Meklat, Atika; Gaceb-Terrak, Rabéa; Oulad Hadj Youcef, Khadidja; Nacer, Asma; Mokrane, Salim; Bouras, Noureddine; Verheecke-Vaessen, Carol
    Actinobacteria isolated from the rhizosphere of plants are of interest as they produce a diverse range of molecules, such as antibiotics and enzymes. This study investigates the antibacterial activity, plant growth-promoting (PGP) abilities as well as the production of extracellular enzymes by the actinobacterial strain BTS40. This strain was isolated from the rhizospheric soil of the medicinal plant Artemisia herba-alba Asso that was naturally grown in a semi-arid environment. Morphological characteristics showed that the strain BTS40 belongs to the genus Streptomyces. Analysis of BTS40’s 16S rRNA gene sequence showed 99.45% similarity to Streptomyces alboniger NRRL B-1832T, in the EzTaxon database. This actinobacterium showed only antibacterial activity against Gram-positive bacteria. The strain also showed potential multiple traits for plant growth promotion and hydrolysis of enzymes. Hence, this study reveals that strain BTS40 has multiple PGP traits and produces many extracellular hydrolytic enzymes.
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    Diversity and bioactivity of endophytic actinobacteria associated with the roots of artemisia herba-alba asso from Algeria
    (Springer Science and Business Media LLC, 2024-12-01) Djemouai, Nadjette; Meklat, Atika; Youcef, Khadidja Oulad Hadj; Nacer, Asma; Saadi, Sid Ahmed; Verheecke-Vaessen, Carol
    The isolation of endophytic actinobacteria from the roots of wild populations of Artemisia herba-alba Asso, a medicinal plant collected from the arid lands of Algeria, is reported for the first time. Forty-five actinobacterial isolates were identified by molecular analysis and in vitro evaluated for antimicrobial activity and plant growth-promoting (PGP) abilities (1-Aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, nitrogen fixation, phosphate and potassium solubilization, ammonia, and siderophores production). The phylogenetic relationships based on 16S rRNA gene sequences show that the genus Nocardioides (n = 23) was dominant in the sampled localities. The remaining actinobacterial isolates were identified as Promicromonospora (n = 11), Streptomyces (n = 6), Micromonopora (n = 3), and Saccharothrix (n = 2). Only six (13.33%) strains (five Streptomyces and one Saccharothrix species) were antagonistic in vitro against at least one or more indicator microorganisms. The antimicrobial activity of actinobacterial strains targeted mainly Gram-positive bacteria. The results demonstrate that more than 73% of the isolated strains had ACC deaminase activity, could fix atmospheric nitrogen and were producers of ammonia and siderophores. However, only one (2.22%) strain named Saccharothrix sp. BT79 could solubilize phosphorus and potassium. Overall, many strains exhibited a broad spectrum of PGP abilities. Thus, A. herba-alba provides a source of endophytic actinobacteria that should be explored for their potential biological activities.
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    Incidence of mycobiota and aflatoxin B1 in Algerian feed
    (Inderscience, 2022-03-29) Bouti, Karima; Mimoune, Nouara Ait; Mokrane, Salim; Djemouai, Nadjette; Verheecke-Vaessen, Carol; Mathieu, Florence; Riba, Amar
    The presence of fungi and aflatoxin B1 (AFB1) in 101 animal feed samples randomly collected from different vendors and factories in Algeria was investigated. For fungi, the main genera isolated were Aspergillus, Penicillium and Fusarium. Furthermore, the 459 strains of Aspergillus section Flavi were screened for their ability to produce aflatoxins and cyclopiazonic acid. 49% of the strains produced AFB1. The highest incidence of aflatoxigenic strains was recorded in maize (61%) and ground poultry feed (60%). The presence of AFB1 in feed samples was evaluated using HPLC-FLD. The obtained data showed that 36.6% of samples were contaminated in the range of 0.34 to 171.06 μg/kg. Six samples exceeded the Algerian maximum limit of 20 µg/kg for AFB1. This study highlights the potential presence of aflatoxigenic strains belonging to section Flavi and AFB1 in animal feed at post-harvest in Algeria, strategic information for the Algerian policies makers.
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    Mycotoxin accumulation in dry rot potato tubers from Algeria and toxigenic potential of associated isolates of fusarium genus
    (Springer Science and Business Media LLC, 2024-10-01) Hadjebar, Sihem; Yekkour, Amine; Djemouai, Nadjette; Matmoura, Amina; Gutierrez-Pozo, Maria; Medina, Angel; Meklat, Atika; Verheecke-Vaessen, Carol
    The presence of different mycotoxins in 232 tuber samples exhibiting dry rot symptoms and their associated Fusarium strains from two production sites in Algeria was investigated. LC–MS/MS was used to simultaneously detect and quantify 14 mycotoxins, including trichothecenes and non-trichothecenes. A total of 49 tubers were contaminated with at least one mycotoxins, including T-2, HT-2, Diacetoxyscirpenol (DAS), 15-acetoxyscirpenol (15-AS) and Beauvericin (BEA). Positive samples from the Bouira region had a significantly higher level of toxin contamination compared to Ain Defla (56.34% and 5.59%, respectively). A total of 283 Fusarium strains were isolated: 155 from Bouira and 128 from Ain Defla. These strains were evaluated for their ability to produce the targeted mycotoxins. The results showed that 61.29% and 53.9% of strains originate from Bouira and Ain Defla regions were able to produce Nivalenol, Fusarenone-X, DAS, 15-AS, Neosolaniol, BEA and Zearalenone. The phylogenetic analysis of the conserved ribosomal internal transcribed spacer (ITS) sequences of 29 Fusarium strains, representative of the recorded mycotoxins profiles, was distributed into 5 Fusarium species complexes (SC): F. incarnatum-equiseti SC (FIESC), F. sambucinum SC (FSAMSC), F. oxysporum SC (FOSC), F. tricinctum SC (FTSC) and F. redolens SC (FRSC). This is the first study determining multiple occurrences of mycotoxins contamination associated to Fusarium dry rot of potato in Algeria and highlights fungal potential for producing trichothecene and non-trichothecens mycotoxins.
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    Polyphasic characterization of Aspergillus section Flavi isolated from animal feeds in Algeria
    (Wiley, 2019-12-13) Bouti, Karima; Verheecke-Vaessen, Carol; Mokrane, Salim; Meklat, Atika; Djemouai, Nadjette; Sabaou, Nasserdine; Mathieu, Florence; Riba, Amar
    In Algeria, little information is available on the population structure of Aspergillus section Flavi in raw materials and resultant animal feeds. A total of 172 isolates belonging to Aspergillus section Flavi were recovered from 57 animal feeds and identified on the basis of macro and micro‐morphological characters, mycotoxin production and genetic relatedness. For the molecular analysis, sequencing of the calmodulin gene (CaM) and the internal transcribed spacer (ITS) regions were performed for representative isolates. Four distinct morphotypes were distinguished: Aspergillus flavus (78.5%), Aspergillus tamarii (19.2%), Aspergillus parasiticus (1.7%), and Aspergillus alliaceus (0.6%). All A. flavus isolates were of the L type and no correlation between sclerotia production and aflatoxigenicity was observed. Our results showed that 68% of the A. flavus strains produced aflatoxins B (AFB), and 72.7% were cyclopiazonic acid (CPA) producers. The three isolates of A. parasiticus were able to produce AFB and aflatoxins G but not CPA whereas, all the strains of A. tamarii produced only CPA. The obtained results revealed the presence of different species of Aspergillus section Flavi, among which were aflatoxin producers. This study provides evidence useful for considerations in aflatoxin control strategies.
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    Streptomyces species from the rhizosphere of the medicinal plant Artemisia herba-alba Asso: screening for biological activities
    (Springer, 2022-05-02) Djemouai, Nadjette; Meklat, Atika; Gaceb-Terrak, Rabéa; Youcef, Khadidja Oulad Hadj; Nacer, Asma; Saadi, Sid Ahmed; Saad, Somia; Verheecke-Vaessen, Carol; Bouras, Noureddine
    This work aims to study cultivable actinobacterial isolated from the rhizosphere soil of Artemisia herba-alba Asso; an important component of the Mediterranean dry steppe flora. The isolates functional attributes with respect to antifungal, in vitro growth-promotion properties and enzymatic capacities, were studied. A total of eleven cultivable actinobacterial strains were isolated and identified as Streptomyces species by 16S rRNA gene sequencing. The eleven Streptomyces strains were positive for the production of almost all the hydrolytic enzymes tested, while the majority had ACC deaminase activity (6 strains) and exhibited ammonia (7 strains), siderophores production (9 strains) and phosphate solubilization (6 strains). Two out of the eleven strains named Streptomyces sp. BKS30 and BKS40 showed antifungal activities. One promising Streptomyces sp. strain BKS30 that was in-depth characterized morphologically and biochemically was further tested for its antifungal activity for the filtrate and the butanolic extract against nine target-fungi as well as for its antioxidant activity by DPPH and ABST tests. The obtained results demonstrate that Streptomyces species isolated from the rhizosphere of Artemisia herba-alba Asso have the potential for different biological activities including antifungal and antioxidant activities particularly for strain BKS30.