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Publications (14)18.92 Total impact

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    Le Trufficulteur Français. 01/2013; 82:17.
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    Le Trufficulteur Français. 01/2013; 82:14-16.
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    ABSTRACT: The diversity of rhizobia associated with introduced and native Acacia species in Algeria was investigated from soil samples collected across seven districts distributed in arid and semi-arid zones. The in vitro tolerances of rhizobial strains to NaCl and high temperature in pure culture varied greatly regardless of their geographical and host plant origins but were not correlated with the corresponding edaphoclimatic characteristics of the sampling sites, as clearly demonstrated by principal component analysis. Based on 16S rRNA gene sequence comparisons, the 48 new strains isolated were ranked into 10 phylogenetic groups representing five bacterial genera, namely, Ensifer, Mesorhizobium, Rhizobium, Bradyrhizobium, and Ochrobactrum. Acacia saligna, an introduced species, appeared as the most promiscuous host because it was efficiently nodulated with the widest diversity of rhizobia taxa including both fast-growing ones, Rhizobium, Ensifer, and Mesorhizobium, and slow-growing Bradyrhizobium. The five other Acacia species studied were associated with fast-growing bacterial taxa exclusively. No difference in efficiency was found between bacterial taxa isolated from a given Acacia species. The tolerances of strains to salinity and temperature remains to be tested in symbiosis with their host plants to select the most adapted Acacia sp.-LNB taxa associations for further revegetation programs.
    FEMS Microbiology Ecology 01/2012; 80(3):534-47. · 3.56 Impact Factor
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    ABSTRACT: In the context of an increasing utilization of the interspecific hybrid Acacia mangium x A. auriculiformis as a plantation tree in the tropical humid zone, its symbiotic characterization was carried out in comparison with that of its two parental species. Rhizobium strains of diverse geographical origins were isolated from root nodules of the hybrid and its parents. Almost all Acacia hybrid isolates were fast growing on yeast extract-mannitol medium, in contrast to those isolated from both parental species, which were mostly slow growing. The rhizobium strains were characterized through partial sequencing of the rRNA operon. In the phylogenetic tree, almost all strains isolated from the hybrid were grouped together in a clade close to Bradyrhizobium japonicum, while all strains isolated from both parental species were close to Bradyrhizobium elkanii. Inoculation experiments performed under in vitro or greenhouse conditions showed that all strains were infective with their original hosts but exhibited very variable degrees of effectivity according to the host plant tested. Thus, homologous strain-host associations were more effective than heterologous ones. This shows that there is still a high potential for isolating and testing new strains from hybrids to be used as inoculants in the context of large-scale afforestation programs.
    Applied and Environmental Microbiology 10/2009; 75(24):7752-9. · 3.95 Impact Factor
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    ABSTRACT: Nine isolates from Argyrolobium uniflorum, Lotus creticus , Medicago sativa (Tunisia) and Lotus arabicus (Senegal) were analysed by multilocus sequence analysis (MLSA) of five housekeeping genes (recA, atpD, glnA, gltA and thrC), the 16S rRNA gene and the nodulation gene nodA. Analysis of the individual and concatenated gene sequences demonstrated that the nine new strains constituted three stable, well-supported (bootstrap and gene sequence similarity values) monophyletic clusters, A, B and C, all belonging to the branch of the genus Ensifer, regardless of the phylogenetic reconstruction method used (maximum likelihood, maximum-parsimony, neighbour-joining). The three groups were further characterized by API 100 auxanographic tests, host specificity and nodA gene sequence analysis. On the basis of these data, clusters A and C are suggested as representing two novel species within the genus Ensifer, for which the names Ensifer numidicus sp. nov. (type strain ORS 1407(T)=LMG 24690(T)=CIP 109850(T)) and Ensifer garamanticus sp. nov. (type strain ORS 1400(T)=LMG 24692(T)=CIP 109916(T)) are proposed. The cluster B strains were assigned to Ensifer adhaerens genomovar A.
    International journal of systematic and evolutionary microbiology 09/2009; 60(Pt 3):664-74. · 2.11 Impact Factor
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    ABSTRACT: Plant symbioses are fundamental for ecosystem stability and sustainability. Introduction of legumes associated with microorganisms efficient in nitrogen fixation and promoting nutrient biodisponibility in limited-nutrient degraded sites is a key step for a successful plant establishment in stress situations such as those encountered in Mediterranean soils. A vegetation strategy based on microbial engineering of locally-adapted plants was investigated and tested in field conditions within the framework of calcareous quarry rehabilitation. Choice of symbiotic plants requires, first, a prospection of native legume species growing in relatively degraded sites in Mediterranean areas and easy to multiply, and second, an identification and production of efficient rhizobial partners. Plants produced in nursery and then transplanted into the quarry showed a good capacity for establishment after three years. Shrub species performed best with spontaneous mycorrhizal association and ability to enrich topsoil with organic matter.
    Cahiers Agricultures 01/2007; 16(4):324-329. · 0.60 Impact Factor
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    ABSTRACT: Sixty-eight new rhizobial isolates were obtained from root-nodules of Medicago laciniata and from Mediterranean soils in Tunisia and France. All of them were identified as Sinorhizobium meliloti on the basis of PCR-RFLP analyses of 16S rDNA and the intergenic spacer sequence between 16S and 23S rDNAs. DNA/DNA hybridization, phenotypic characterization and 16S rRNA gene sequencing led to the conclusion that they belong the same taxon. All new isolates shared the ability to nodulate and fix nitrogen with M. laciniata except 11 of them not capable of fixing nitrogen with this plant and originating from French soils containing no efficiently adapted symbionts with M. laciniata. The nitrogen-fixing rhizobia on M. laciniata differed markedly from the other S. meliloti or Sinorhizobium medicae isolates and references in their symbiotic traits such as nifDK RFLP diversity, nodA sequences and nitrogen effectiveness with tree other different annual Medicago species (M. truncatula, M. polymorpha and M. sauvagei). Two infrasubspecific (biovar) divisions are therefore proposed within S. meliloti: bv. medicaginis for Sinorhizobium efficient on M. laciniata and bv. meliloti for the classically known S. meliloti group represented by the strains ATCC9930(T) and RCR 2011 efficient on M. sativa.
    Systematic and Applied Microbiology 12/2006; 29(7):526-38. · 3.29 Impact Factor
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    ABSTRACT: We studied symbiosis of Medicago ciliaris and Medicago polymorpha, two legumes of forage and ecological importance in Algeria, especially in saline soil regions. We report the spatial distribution of the two species and their microsymbionts along salinity gradient transects in the Sebkha of Misserghin (Algeria, North Africa). Seeds and root nodules were sampled from 10 sites. Twenty-seven rhizobial strains were isolated from root nodules and characterized as fast-growers and slime-producers on yeast mannitol agar. By partial sequencing of the gene coding for the 16 S ribosomal RNA, they were found to be affiliated to Rhizobium, Sinorhizobium, and Agrobacterium but several strains had sequences with separate positions.Interestingly one of these was further assigned to Phyllobacterium. Opposite to rhizobia, the distribution of the two Medicago species varied along the salinity gradient, M. ciliaris being dominant in the low NaCl concentration zones and M. polymorpha dominant in the most saline zones. Tolerance to salinity, of both bacterial and plant partners, was studied under laboratory conditions, showing that plants are susceptible to NaCl concentrations of 50 mM, 15-fold lower than that of their associated rhizobia (800 mM).
    Arid Land Research and Management 07/2006; 20(3):219-231. · 0.56 Impact Factor
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    ABSTRACT: Legumes contribute to soil fertility and to 33% of global human food needs and up to 80% in developing countries. This success is mainly due to the symbiosis they establish with nitrogen-fixing bacteria. This symbiosis is characterised by (1) its specificity between plants and bacteria (2) a plant can be nodulated by several different bacterial species (3) the nitrogen-fixing efficiency depends on both partners. The techniques used for bacterial characterisation have greatly evolved during the past twenty years and include increasing molecular techniques. In the same time taxonomical and diversity studies on Legume Nodulating Bacteria ("LNB") have multiplied, in particular on rhizobia associated to understudied plants and regions so far. Numerous new species have been proposed, and at present LNBs include over 13 genera and 50 valid species. Phylogenetically LNBs belong to six families inside the sub-phyla α and β of the Proteobacteria phylum. They are intertwined with other bacterial species, several of which being involved in other kinds of interactions with plants (pathogenicity, growth promotion) or with mammals (pathogenicity). Here we present the recent advances in LNB taxonomy, focusing on bacteria associated to tropical legumes, emphasizing on unexpected functions associated to them, stem nodulation, free-living nitrogen-fixation, photosynthesis, endophytic association with non-legumes, biodegradative properties, opening new perspectives as fundamental models for research and for applications in future.
    01/2006: pages 105-141; , ISBN: 8130801388
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    ABSTRACT: Wood-decay white-rot and brown-rot fungi have a major economic impact on commercial and manufactured tropical and temperate woods. The aim of this study was to design a molecular method, coupled with polymerase chain reaction (PCR) and DNA sequencing, to enable early identification of various forms of fungal decay in various types of wood. The resulting tool could be used to certify the healthiness of commercial woods and also to make more efficient use of chemicals and thus reduce their negative environmental impact. Sapwood plates of Distemonanthus benthamianus,Fagus sylvatica, Lophira alata, Pinus sylvestris, and Pycnanthus angolensis were incubated in vitro in the presence of Fibroporia vaillantii, Coniophora puteana, Gloeophyllum trabeum, Pycnoporus sanguineus, and Trametes versicolor according to the EN 113 standard method. Average mass losses ranging from 2.6% to 25.0% indicated that all wood samples had been actually infected and enabled us to test the reliability of our method. PCR products were obtained in 24 of 25 combinations, and DNA sequences were obtained in 21 of the 24 fungal PCR products. DNA sequences obtained from infected wood were compared with sequences from pure strains, thus confirming the identity of the infecting strains with 100% similarity for an average of 412 bp.
    Canadian Journal of Forest Research 02/2005; 35(5):1256-1260. · 1.56 Impact Factor
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    ABSTRACT: We report on the isolation and the characterization of nitrogen-fixing root nodule bacteria isolated from natural legumes in a region of South Tunisia corresponding to the infra-arid climatic zone. A collection of 60 new bacterial root nodule isolates were obtained from 19 legume species belonging to the genera Acacia, Anthyllis, Argyrolobium, Astragalus, Calycotome, Coronilla, Ebenus, Genista, Hedysarum, Hippocrepis, Lathyrus, Lotus, Medicago, Ononis. The isolates were characterised by (1) comparative 16S ARDRA using 7 enzymes, (2) total cell protein SDS-PAGE analysis and (3) 16S rDNA sequencing. The results show that these isolates are diverse and belong to the genera Rhizobium, Sinorhizobium, Mesorhizobium and Bradyrhizobium. Bradyrhizobium were further characterised by 16S-23S rDNA IGS sequencing. Surprisingly strains nodulating Astragalus cruciatus, Lotus creticus and Anthyllis henoniana were identified as Rhizobium galegae, a species recorded only as endosymbiont of Galega officinalis and G. orientalis in northern regions so far.
    Systematic and Applied Microbiology 06/2004; 27(3):380-95. · 3.29 Impact Factor
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    ABSTRACT: Poster Cleyet-Marel J.C., Larcher M., Bertrand H., Rapior S. et Pinochet X. Plant Growth Enhancement by Rhizobacteria. In: Nitrogen Assimilation by Plants. Physiological, Biochemical and Molecular Aspects. Ed. J.F. Monod-Gaudry, Science Publishers Inc. Enfield (USA). pp 185-197 (2001). Larcher M., Muller B., Mantelin S., Rapior S. et Cleyet-Marel J.C. Early modifications of Brassica napus root system architecture induced by a plant growth-promoting Phyllobacterium strain. New Phytologist, 160, 119-125 (2003).
    XIIIèmes Journées Scientifiques Nationales STOLON (Besançon, France, 9-10/09/2002)., Besançon, France, 9-10/09/2002; 01/2002
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    ABSTRACT: Poster Larcher M., Muller B., Mantelin S., Rapior S. et Cleyet-Marel J.C. Early modifications of Brassica napus root system architecture induced by a plant growth-promoting Phyllobacterium strain. New Phytologist, 160, 119-125 (2003). Larcher M., Rapior S. et Cleyet-Marel J.C. Bacteria from the rhizosphere and roots of Brassica napus rhizosphere influence its root growth promotion by Phyllobacterium brassicacearum. Acta bot. Gallica, 155 (3,) 355-366 (2008).
    Fifth International PGPR (Plant Growth-Promoting Rhizobacteria) Workshop (Villa Calos Paz, Cordoba, Argentine, 30/10-3/11/2000), p 65., Villa Calos Paz, Cordoba, Argentine, 30/10-3/11/2000; 01/2000