Search

The root nodule bacteria were isolated from three different leguminous plants belonging to the Fabaceae family such as Cajanus cajan, Lablab purpureus and Vigna unguiculata using YEMA medium and identified. The isolates were submitted to 16S rRNA and PCR–RFLP typing. A representative sample was further submitted to sequence analysis of 16S rRNA. Isolates were assigned to two genera and were related to Rhizobium spp. (75%) and Bacillus spp. (25%) respectively. This study opens the doors to researchers to do specific studies on this root nodule bacteria which are symbiotic with these legume plants in this area for their antibacterial activity, medicine and food application, and sustainable agriculture.  Rhizobium and other beneficial microbes may be used as biofertilizers as a substitute for chemical fertilizers.

Ensifer medicae (syn. Sinorhizobium medicae) strain WSM1115 forms effective nitrogen fixing symbioses with a range of annual Medicago species and is used in commercial inoculants in Australia. WSM1115 is an aerobic, motile, Gram-negative, non-spore-forming rod. It was isolated from a nodule recovered from the root of burr medic (Medicago polymorpha) collected on the Greek Island of Samothraki. WSM1115 has a broad host range for nodulation and N2 fixation capacity within the genus Medicago, although this does not extend to all medic species. WSM1115 is considered saprophytically competent in moderately acid soils (pHCaCl2 5.0) however, has failed to persist at field sites where soil salinity exceeded 10 ECe (dS/m). Here we describe the features of E. medicae strain WSM1115, together with genome sequence information and its annotation. The 6,861,065 bp high-quality-draft genome is arranged into 7 scaffolds of 28 contigs, contains 6,789 protein-coding genes and 83 RNA-only encoding genes, and is one of 100 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project.

The ability of wild indigenous legumes to form root nodules capable of biological nitrogen (N 2) fixation has rarely been demonstrated for species in natural ecosystems in large parts of Europe. In order to understand and manage these ecosystems, it is important to demonstrate nodulation across a diverse range of environments, sites and climates. This study surveyed nodulation at a number of sites in Scotland and Sweden. Presence of nodules was noted and nodule structure and indicators of nitrogen fixation capacity were assessed using light and transmission electron microscopy. Soils from several sites were also sampled for carbon and nitrogen analysis. The collections comprised 24 species in Scotland, and 30 taxa in Sweden; 17 of these in common for both countries. Highest species numbers occurred in meadows, farmland margins, hedgerows, roadsides and wasteland. Coastal sites and sites in the mountainous region above the Arctic Circle hosted several rare species. All sampled species had features of N 2-fixing nodules such as pink colour (leghaemoglobin) when dissected and bacteroids. Nodule structure for a number of species is here reported for the first time and presence of the N 2-fixing enzyme nitrogenase is demonstrated in three previously not studied Swedish legume species. North European legumes may make significant contributions to the N-budgets of their ecosystems. Such species (and their symbionts) represent unique germplasm that may be adopted to empower advances in agriculture and conservation aimed at mitigation and adaptation to the effects of climate change., QC 20121204

De Meyer, S. E., Ruthrof, K. X., Edwards, T., Hopkins, A. J., Hardy, G., O’Hara, G., & Howieson, J. (2018). Diversity of endemic rhizobia on Christmas Island: Implications for agriculture following phosphate mining. Systematic and Applied Microbiology. Available here.