Abstract
Bacteria like Enterobacter, Pseudomonas and Klebsiella are characterized by causing diseases in human and at the same time they live as endophytes and promote plants growth. The aim of this study was to investigate enophytic bacteria associated with leguminous plants in Gadarif State soils and explore the phylogenetic relationship among the endophytic bacteria and the clinical one. Nodules from groundnut, cowpea and Bambara groundnut collected from 11 localities of Gadarif State, Enterobacter spp., Pseudomonas spp. and Klebsiella spp were isolated. Genomic DNA was extracted and 16srRNA and nifH genes were sequenced. Twenty-five isolates belonging to Enterobacter, Pseudomonas and Klebsiella spp were obtained which were found to share biochemical characters with fast growing Rhizobia. The 16srRNA sequences analysis revealed that they belong to Enterobacter cloacae, Pseudomonas fluoresecens, Pseudomonas rhizophaerae, Klebsiella pneumonia and Klebsiella variicola. The GC content was 54 - 56% for Enterobacter cloacae, 54 - 55% for Klebsiella pneumonia, 55 - 57% for Klebsiella variicola and 52 - 53% for Pseudomonas fluoresecens.
The phylogeny tree based on 16srRNA classified all endophytic bacteria in this study to different clusters descending from the same ancestors. All isolates have the ability to coloninze the three legumes used in this study regardless the environment and the place where they are grown. The study concluded that Gadarif state soil is dominated by these useful endophytic bacteria which preserve its fertility and searching for virulent genes in these bacteria is recommended if there is interest to use as inoculants.