Molecular Identification and Phylogeny of Endophytic Bacterial Communities Isolated from some Legumes Using 16SrDNA

Bacterial endophytes are host-beneficial microbial symbionts inhabiting different plant tissues without causing damage to the host plant. To our knowledge, no previous data was available regarding the endophytic bacterial population colonizing root nodules of plant legumes in this region. Therefore, this study was conducted to identify and assess the biodiversity of the bacterial endophytes of four different legumes species of the Fabaceae family, including Chickpea, Faba bean, Common bean, and Lentil in Duhok province, using 16S rDNA sequencing. The results revealed that 69 different pure culture colonies were isolated based on the phenotypic characteristics of endophytes on YEM medium and Gram staining. Based on 16S rDNA sequencing, seventeen bacterial species have been identified, with the sequence identities ranging from 98.41-100%. They belonged to nine different bacterial genera. The identified bacterial genera were Pantoea sp. (35%), Enterobacter sp. (26%), Clostridium sp. (15%), Kosakonia sp. (9%), Pseudomonas sp. (4%), Curtobacterium sp. (4%), Erwinia sp. (3%), Salmonella sp. (3%), and Rahnella sp. (1%). These bacterial genera belonged to four Phyla, including Pseudomonadota , Bacillota , Proteobacteria , and Actinobacteria . The antibacterial sensitivity against six various antibiotics by disc diffusion method showed different resistant patterns (bacitracin 78%, amoxicillin 56%, rifampin 34%, erythromycin 11%, chloramphenicol and tetracycline 6%), respectively. The phylogenetic analysis clustered the identified bacterial endophytes into three major clades and 11 different sub-clusters (C1 to C11), with a high degree of similarity amongst bacteria belonging to the same species. In conclusion, the population densities, species richness, and frequency of isolated endophytes showed variations based on geographical locations and the type of plant legumes. Finally, the results of the current investigation might add significant knowledge regarding endophytic bacterial populations colonizing different plant legumes in this region