Diversity of actinobacteria in the marshes of Ezzemoul and Djendli in northeastern Algeria

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 isolated strains that tolerate 10% NaCl may have a very interesting biotechnological potential in the future. ABSTRACT Actinobacteria; sebkha; culture; cloning; 16S rRNA gene; phylogenetic biodiversity KEYWORDS

Characterization of Plant Growth-Promoting Traits and Inoculation Effects on Triticum durum of Actinomycetes Isolates under Salt Stress Conditions

“…Our previous studies have shown that several actinomycetes isolated from Algerian saline soils (salt tolerance up to 10% (i.e., 1.7 M)) [29] have good in vitro and in planta (Solanum lycopersicum L.) plant growth-promoting (PGP) traits under normal conditions [30]. In this study, we advanced the hypothesis that these strains could be valid agents to salt stress tolerance.…”

“…The actinomycetes strains were isolated from two saline sites in the northeast region of Algeria, Ezzemoul sebkha-35 • 53 14 North; 06 • 30 20 East; pH 8.6; EC (electrical conductivity) 1600 µS cm −1 ; organic matter 6.0%; moisture and organic matter 6.0%; sand 52.8%; slit 22.4%; clay 24.8%-and Djendli sebkha-35 • 43 15 North; 06 • 32 23 East; pH 8.0; EC 1101 µS cm −1 ; organic matter 6.2%; moisture and organic matter 5.8%, sand 31.0%; slit 32.7%; clay 36.3% [29,30]. The soil samples were taken according to the Pochon and Tardieux method [31].…”

Actinomycete Strains Isolated from Saline Soils: Plant-Growth-Promoting Traits and Inoculation Effects on Solanum lycopersicum

“…Based on these results, among the 60 strains tested, 14 strains were selected as promising PGPB: These isolates tolerated up to 10% NaCl during in vitro testing, suggesting halotolerant traits [25].…”

Biocontrol of Soil-Borne Pathogens of Solanum lycopersicum L. and Daucus carota L. by Plant Growth-Promoting Actinomycetes: In Vitro and In Planta Antagonistic Activity

“…The following fourteen strains of actinomycetes, previously isolated and characterized [62], were used in this study:…”