ABSTRACT

Bacteria in the rhizosphere that can penetrate plant tissues are referred to as endophytes. Numerous studies have explored the presence of bacteria in various plant parts such as nodules, roots, stems, leaves, flowers, and seeds. Plant growth promoting rhizobacteria (PGPR) can directly or indirectly enhance plant growth. This study was aimed at isolating and identifying the endophytic bacteria associated with cowpea root   nodules. Standard bacteriological methods were used to determine the total bacterial count using pour plate methods after serial dilution. The bacterial isolates were characterized and identified using morphological and biochemical methods. The percentage distribution and frequency of the isolates were evaluated using statistical method. The bacterial population obtained from the root nodules ranged from 5.77 log₁₀cfu/g to 5.911 log₁₀ cfu/g. Using standard cultural and morphological characteristics, the isolates obtained in this study were Bacillus subtilis, Bacillus cereus, Pseudomonas sp, and a Rhizobium sp. All isolates obtained in this study were positive for indole acetic acid (IAA), with Pseudomonas sp and Rhizobium sp also testing positive for the ammonia test. The HCN test revealed that all isolates were positive except Bacillus subtilis. Endophytes can transport nitrogen directly to plants. Consequently, free-living diazotrophic endophyte bacteria have been a prime focus of research in recent decades. The phosphate solubility test demonstrated that all isolates were phosphate solubilizers, with Pseudomonas and Bacillus exhibiting halozones of 15.5mm each. Consequently, the opportunity to find new and beneficial endophytic microorganisms among the diversity of plants in different ecosystems is considerable. Endophytic bacteria have been isolated from a large diversity of plants.