Diverse Bacteria Associated with Root Nodules of Spontaneous Legumes in Tunisia and First Report for nifH-like Gene within the Genera Microbacterium and Starkeya

Abstract

We characterized 34 endophytic bacterial isolates associated to root nodules collected from spontaneous legumes in the arid zone of Tunisia by 16S rDNA polymerase chain reaction (PCR)-restriction fragment length polymorphism, whole cell protein sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), 16S rDNA and 16S-23S rDNA internal transcribed spacer sequencing. Phylogenetically, these isolates belong to the branches containing the genera Inquilinus, Bosea, Rhodopseudomonas, Paracraurococcus, Phyllobacterium, Ochrobactrum, Starkeya, Sphingomonas, Pseudomonas, Agromyces, Microbacterium, Ornithinicoccus, Bacillus, and Paenibacillus. These strains did not induce any nodule formation when inoculated on the wide host spectrum legume species M. atropurpureum (Siratro) and no nodA gene could be amplified by PCR. However, nifH sequences, most similar to those of Sinorhizobium meliloti, were detected within strains related to the genera Microbacterium, Agromyces, Starkeya and Phyllobacterium.

1,003 reference genomes of bacterial and archaeal isolates expand coverage of the tree of life

“…Indeed, Inquilinus spp. have been previously reported in 16S rRNA surveys of root nodules of wild legumes 32,33 . There is mounting evidence that human-pathogenic enteric bacteria such as Salmonella can colonize plant tissues, and use similar mechanisms for infection of animal and plant hosts 34,35 .…”

A large diversity of non-rhizobial endophytes found in legume root nodules in Flanders (Belgium)

“…However, in our study no symbiosis or nitrogen fixation related genes were detected for the isolates of this genus. Some genera including, Arthrobacter, Microbacterium, Rhodococcus, Sphingomonas, Bacillus, Cohnella, Pseudomonas and Herbaspirillum, were previously reported from root nodules of several legume species (Sturz et al, 1997;Mantelin et al, 2006;Zakhia et al, 2006;Putnam and Miller, 2007;Zurdo-Pineiro et al, 2007;Palaniappan et al, 2010). Other bacterial genera encountered, including Pantoea, Corynebacterium, Chryseobacterium, Sphingomonas and Xanthomonas, were described previously as endophytes in certain plant tissues including legume plant tissue (Burch and Sarathchandra, 2006).…”

Multilocus sequence analysis of root nodule isolates from Lotus arabicus (Senegal), Lotus creticus, Argyrolobium uniflorum and Medicago sativa (Tunisia) and description of Ensifer numidicus sp. nov. and Ensifer garamanticus sp. nov.

“…PCR amplification of the atpD, recA, gltA, thrC and glnA genes was performed as described by Martens et al (2007) with the exception that the total volume of the reaction mixture was 25 ml. PCR amplification of the 16S rRNA gene was performed according to Zakhia et al (2004) and nodA gene amplification was conducted as described by Zakhia et al (2006).…”