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  1. Article ; Online: Diversity of actinobacteria in the marshes of Ezzemoul and Djendli in northeastern Algeria

    Maria Smati / Mahmoud Kitouni

    European Journal of Ecology, Vol 5, Iss

    2019  Volume 2

    Abstract: The main purpose of this research is to study the microbial diversity of actinobacteria, living in “Ezzemoul” and “Djendli” sebkhas soils. These salt lakes are situated in the east of Algeria and they are microbiologically underexploited. Such unexplored ...

    Abstract The main purpose of this research is to study the microbial diversity of actinobacteria, living in “Ezzemoul” and “Djendli” sebkhas soils. These salt lakes are situated in the east of Algeria and they are microbiologically underexploited. Such unexplored ecological niches have been considered by many authors as sources of novel actinobacteria and bioactive molecules. Actinobacteria play an important role in safeguarding the environment by improving plant growth through nitrogen fixation, biodegradation, and bioremediation. Therefore, studying the diversity and distribution of actinobacteria in such special environments is important for determining the ecological and biotechnological roles of these microorganisms. In this article, we focused on the occurrence and the diversity of actinobacteria from sebkhas using two techniques: cultural and culture-independent (molecular cloning). The latter are based on phylogenetic analysis of the 16S rDNA gene. Thus, the cultural method allowed us to obtain 62 isolates: 40 from the “Ezzemoul” site and 22 from the “Djendli” site. These isolates tolerate mainly 2, 5, and 10% sodium chloride (NaCl) and belong to the genera Nocardiopsis, Streptomyces, and Rhodococcus. Moreover, the molecular cloning gave us 39 clones. Twenty-four clone sequences from “Ezzemoul” site are affiliated to the genera Demequina, Plantactinospora, Friedmanniella, and Mycobacterium. Also, 15 clone sequences from “Djendli” site are related to the genera Marmoricola, Phytoactinopolyspora, Streptomyces, and to an unclassified actinobacterial clone. Some sequences from both sites are related to uncultured clones. In addition to the data provided by the cultural method, molecular cloning allowed us to have additional information about the unknown actinobacteria, uncultured ones as well as on the genera that exist in both sites. So, the cultural method is complementary to the culture-independent one, and their combination revealed an important diversity in targeted saline environments. Furthermore, all new ...
    Keywords actinobacteria ; sebkha ; culture ; cloning ; 16s rRNA gene ; phylogenetic biodiversity ; Ecology ; QH540-549.5
    Subject code 590
    Language English
    Publishing date 2019-12-01T00:00:00Z
    Publisher University of Kansas Libraries
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Biocontrol of Soil-Borne Pathogens of Solanum lycopersicum L. and Daucus carota L. by Plant Growth-Promoting Actinomycetes

    Rihab Djebaili / Marika Pellegrini / Claudia Ercole / Beatrice Farda / Mahmoud Kitouni / Maddalena Del Gallo

    Pathogens, Vol 10, Iss 1305, p

    In Vitro and In Planta Antagonistic Activity

    2021  Volume 1305

    Abstract: Biotic stress caused by pathogenic microorganisms leads to damage in crops. Tomato and carrot are among the most important vegetables cultivated worldwide. These plants are attacked by several pathogens, affecting their growth and productivity. Fourteen ... ...

    Abstract Biotic stress caused by pathogenic microorganisms leads to damage in crops. Tomato and carrot are among the most important vegetables cultivated worldwide. These plants are attacked by several pathogens, affecting their growth and productivity. Fourteen plant growth-promoting actinomycetes (PGPA) were screened for their in vitro biocontrol activity against Solanum lycopersicum and Daucus carota microbial phytopathogens. Their antifungal activity was evaluated against Fusarium oxysporum f. sp. radicis-lycopersici (FORL) and Rhizoctonia solani (RHS). Antibacterial activity was evaluated against Pseudomonas syringae , Pseudomonas corrugata , Pseudomonas syringae pv. actinidiae , and Pectobacterium carotovorum subsp. carotovorum . Strains that showed good in vitro results were further investigated in vitro (cell-free supernatants activity, scanning electron microscope observations of fungal inhibition). The consortium of the most active PGPA was then utilized as biocontrol agents in planta experiments on S. lycopersicum and D. carota . The Streptomyces albidoflavus H12 and Nocardiopsis aegyptica H14 strains showed the best in vitro biocontrol activities. The diffusible and volatile compounds and cell-free supernatants of these strains showed both antifungal (in vitro inhibition up to 85%, hyphal desegregation and fungicidal properties) and antibacterial activity (in vitro inhibition >25 mm and bactericidal properties). Their consortium was also able to counteract the infection symptoms of microbial phytopathogens during in planta experiments, improving plant status. The results obtained highlight the efficacy of the selected actinomycetes strains as biocontrol agents of S. lycopersicum and D. carota .
    Keywords PGPB ; actinomycetes ; antifungal activity ; antibacterial activity ; cell culture filtrate ; SEM ; Medicine ; R
    Subject code 571
    Language English
    Publishing date 2021-10-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Actinomycete Strains Isolated from Saline Soils

    Rihab Djebaili / Marika Pellegrini / Maria Smati / Maddalena Del Gallo / Mahmoud Kitouni

    Sustainability, Vol 12, Iss 4617, p

    Plant-Growth-Promoting Traits and Inoculation Effects on Solanum lycopersicum

    2020  Volume 4617

    Abstract: Excessive use of chemical products in agriculture is causing significant environmental pollution and the loss of lands and fertility of agricultural soils. Plant-growth-promoting bacteria are a valid alternative strategy for sustainable agriculture. The ... ...

    Abstract Excessive use of chemical products in agriculture is causing significant environmental pollution and the loss of lands and fertility of agricultural soils. Plant-growth-promoting bacteria are a valid alternative strategy for sustainable agriculture. The aim of this study was to select actinomycete strains based on their plant-growth-promoting traits and to investigate their root association abilities and biostimulant effects on Solanum lycopersicum . The strains were investigated for their phosphate solubilization ability, production of indole-3-acetic acid, hydrocyanic acid, and ammonia, and several enzymatic activities. Bacteria–plant-root associations were studied by scanning electron microscopy. A greenhouse experiment was carried out to assess inoculation effects. Of sixty isolates, fourteen strains showed significant plant-growth-promoting traits. All fourteen strains solubilized phosphate, produced ammonia, and showed several enzymatic activities at different rates. The production of indole-3-acetic acid was shown by nine strains, while hydrocyanic acid production was observed in eleven of them. Scanning electron microscopy revealed that strains have good in vitro plant root association and colonization abilities. In planta inoculation by actinomycete strains positively influenced plant growth parameters. The best results were shown by seven actinomycete strains, suggesting their possible utilization as biofertilizer agents for sustainable agriculture.
    Keywords PGPB ; actinomycetes ; phosphate solubilization ; indole-3-acetic acid ; hydrocyanic acid ; tomato ; Environmental effects of industries and plants ; TD194-195 ; Renewable energy sources ; TJ807-830 ; Environmental sciences ; GE1-350
    Language English
    Publishing date 2020-06-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Characterization of Plant Growth-Promoting Traits and Inoculation Effects on Triticum durum of Actinomycetes Isolates under Salt Stress Conditions

    Rihab Djebaili / Marika Pellegrini / Massimiliano Rossi / Cinzia Forni / Maria Smati / Maddalena Del Gallo / Mahmoud Kitouni

    Soil Systems, Vol 5, Iss 26, p

    2021  Volume 26

    Abstract: This study aimed to characterize the halotolerant capability, in vitro, of selected actinomycetes strains and to evaluate their competence in promoting halo stress tolerance in durum wheat in a greenhouse experiment. Fourteen isolates were tested for ... ...

    Abstract This study aimed to characterize the halotolerant capability, in vitro, of selected actinomycetes strains and to evaluate their competence in promoting halo stress tolerance in durum wheat in a greenhouse experiment. Fourteen isolates were tested for phosphate solubilization, indole acetic acid, hydrocyanic acid, and ammonia production under different salt concentrations (i.e., 0, 0.25, 0.5, 0.75, 1, 1.25, and 1.5 M NaCl). The presence of 1-aminocyclopropane-1-carboxylate deaminase activity was also investigated. Salinity tolerance was evaluated in durum wheat through plant growth and development parameters: shoot and root length, dry and ash-free dry weight, and the total chlorophyll content, as well as proline accumulation. In vitro assays have shown that the strains can solubilize inorganic phosphate and produce indole acetic acid, hydrocyanic acid, and ammonia under different salt concentrations. Most of the strains (86%) had 1-aminocyclopropane-1-carboxylate deaminase activity, with significant amounts of α-ketobutyric acid. In the greenhouse experiment, inoculation with actinomycetes strains improved the morpho-biochemical parameters of durum wheat plants, which also recorded significantly higher content of chlorophylls and proline than those uninoculated, both under normal and stressed conditions. Our results suggest that inoculation of halotolerant actinomycetes can mitigate the negative effects of salt stress and allow normal growth and development of durum wheat plants.
    Keywords PGPB ; actinomycetes ; 1-aminocyclopropane-1-carboxylate deaminase ; durum wheat ; salt stress ; halotolerance ; Physical geography ; GB3-5030 ; Chemistry ; QD1-999
    Subject code 580
    Language English
    Publishing date 2021-04-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article: Chitinolytic actinobacteria isolated from an Algerian semi-arid soil: development of an antifungal chitinase-dependent assay and GH18 chitinase gene identification

    Gasmi, Meriem / Mahmoud Kitouni / Lorena Carro / Petar Pujic / Philippe Normand / Hasna Boubakri

    Annals of microbiology. 2019 Apr., v. 69, no. 4

    2019  

    Abstract: The purpose of this study was to explore the microbial potential of a semi-arid sandy soil from south-central Algeria in order to isolate new chitinolytic actinobacteria. This soil is subjected to high temperatures (up to 43 °C) and has low nutrient ... ...

    Abstract The purpose of this study was to explore the microbial potential of a semi-arid sandy soil from south-central Algeria in order to isolate new chitinolytic actinobacteria. This soil is subjected to high temperatures (up to 43 °C) and has low nutrient content. Strains were isolated by plating soil suspensions on Bennett and Colloidal Chitin (CCM) medium. An initial clustering of isolates was made through BOX-PCR genetic profiling. Next, a 16S rRNA gene sequencing of representative isolates was realized. We also identified optimum physicochemical conditions for chitinolytic activity. A rapid in vitro assay based on glucose catabolic repression was developed to select isolates having a chitinase-dependent antifungal activity against two phytopathogenic fungi. Gene identification of glycosyl hydrolase family 18 (GH18) permitted us to assess the divergence of chitinase genes. Forty isolates were obtained from the semi-arid sandy soil. The molecular identification permitted us to assign them to Streptomyces or Micromonospora genera with seven possibly new bacterial species. For chitinolytic activity, 100% of isolates were able to grow and degrade colloidal chitin at pH 7 and at a temperature ranging from 30 to 40 °C. We also observed that Micromonospora strains had atypical activity patterns, with a strong chitinase activity maintained at high temperature. Finally, three strains presented an interesting chitinolytic potential to reduce fungal growth with new GH18 sequences. This study presents a new rapid method to detect antifungal chitinase-dependent activity that allowed to identify potentially new species of actinobacteria and new GH18 gene sequences.
    Keywords Micromonospora ; Streptomyces ; antifungal properties ; chitin ; chitinase ; enzyme activity ; fungal growth ; genes ; glucose ; in vitro studies ; new species ; nutrient content ; pH ; plant pathogenic fungi ; rapid methods ; ribosomal RNA ; sandy soils ; sequence analysis ; temperature ; Algeria
    Language English
    Dates of publication 2019-04
    Size p. 395-405.
    Publishing place Springer International Publishing
    Document type Article
    ZDB-ID 2143009-3
    ISSN 1869-2044 ; 1590-4261
    ISSN (online) 1869-2044
    ISSN 1590-4261
    DOI 10.1007/s13213-018-1426-z
    Database NAL-Catalogue (AGRICOLA)

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