Isolation of Elaeagnus-compatible Frankia from soils collected in Tunisia

Abstract

The occurrence and diversity of Frankia nodulating Elaeagnus angustifolia in Tunisia were evaluated in 30 soils from different regions by a Frankia-capturing assay. Despite the absence of actinorhizal plants in 24 of the 30 soils, nodules were captured from all the samples. Eight pure strains were isolated from single colonies grown in agar medium. On the basis of 16S rRNA and GlnII sequences, seven strains were clustered with Frankia, colonizing Elaeagnaceae and Rhamnaceae in two different phylogenetic groups while one strain described a new lineage in the Frankia assemblage, indicating that Frankia strains genetically diverse from previously known Elaeagnus-infective strains are present in tunisian soils. Genomic fingerprinting determined by rep-PCR, and tDNA-PCR-SSCP, confirmed the wide genetic diversity of the strains.

Actinobacteria Isolation from Metal Contaminated Soils for Assessment of their Metal Resistance and Plant Growth Promoting (PGP) Characteristics

“…Slow growing, melanotrophic actinobacteria Actinobacteria Isolating Agar (AIA) Minimal medium Fast and slow growing actinobacteria (Baskaran et al, 2011) Defined Propionate Medium (DPM) and Buffered Ammonium Propionate (BAP) Specific for Frankia species (Gtari et al, 2004) International Streptomyces Project (ISP) Media (1 to 9)…”

“…The ISP (International Streptomyces Project) family media have been used for studying physiological characteristics of already isolated actinobacteria. Slow growing nitrogen fixing actinobacterial taxa belonging to genus Frankia that were found associated with actinhorizal plants, can be isolated in liquid media like buffered ammonium propionate (BAP) or defined propionate medium (DPM) (Gtari et al, 2004). Compared to Luedemann or AIA, these media are minimal and thus, limit colonization by fast growing bacteria.…”

Molecular diversity of Frankia from root nodules of Hippophae salicifolia D.Don found in Sikkim

“…This is indicative of a larger diversity for Frankia nodulating Hippophae salicifolia compared to that nodulating alder. Elaeagnus compatible Frankia isolated from soils collected from Tunisia too showed large diversity [16]. On the other hand, Clawson et al [17] found a shallow level of diversity in the 16S rDNA analysis of family Elaeagnaceae.…”

Genetic and functional heterogeneities among fluorescent Pseudomonas isolated from environmental samples

“…The 16S rRNA gene PCR products were purifi ed from PCR reaction mixtures using the QIAquick Wizard PCR Purifi cation Kit (Promega), according to manufacturers instructions. The sequences were determined by cycle sequencing using the Taq Dye Deoxy Terminator Cycle Sequencing Kit (Applied Biosystems, HTDS, Tunisia), and underwent fragment separation in an ABI Prism 3130 DNA sequencer as previously described (Gtari et al, 2004). Similarity matrix of 16S rRNA gene sequences with closest neighbors and identifi cation were achieved using the EzTaxon server (http://www.eztaxon.…”

“…BOX-PCR was performed as described by Gtari et al (2004). Mixtures contained 1 PCR buf-fer, 2 mM MgCl 2 , 0.1 mM dNTPs, 0.8 µM of BOX-A1R primer, 5% of dimethylsulfoxide, 1.3 U of Taq DNA polymerase and standardized 15 ng of genomic DNA in a fi nal volume of 30 µl.…”