Morphological and Molecular Characterization of Endophytic Bacteria Isolated from Bambara Groundnut (Vigna subterranea) Nodules in Daloa, Côte d’Ivoire

A thorough understanding of the diversity, functions and specific interactions of endophytic bacteria present in legumes is essential for improving crop production. This study aimed to identify roots nodule endophytes associated to Bambara groundnut by analyzing their morphological diversity and genetic diversity. A total of 34 bacterial isolates were sampled from different cultivation sites and associated with 5 local varieties of Bambara groundnut.

Morphological analysis using macroscopic and microscopic observation revealed that the bacterial isolates were morphologically diverse in terms of colony appearance, shape, colony size, color, opacity and Gram stain result. These bacteria exhibited characters different from those of the symbiotic bacteria. In addition, molecular identification based on sequencing the 16S-rRNA gene and 1081 bp analysis showed the existence of non-symbiotic bacteria in Bambara groundnut nodule. The community of roots nodule endophyte isolated from Bambara groundnut belonged to the genera Pseudomonas, Bacillus, Bacterium, microbacterium, Rahnella, Paenibacillus, Lysobacter with 98 to 99.5% similarity, classified under the Firmicutes, Actinobacteria and Proteobacteria phyla. In Bambara groundnut, the predominant nodule endophytes were Bacillus (56%) and Pseudomonas (17%).

Future research could further investigate the ecological implications of these bacterial interactions, and their potential applications in biotechnology and agronomy, particularly in biofertilization and host plant growth promotion.