Molecular Identification and Antimicrobial Activity of Rhizobacteria Isolated from Plants in The North of Iraq

In the winter of 2023, four isolates of rhizobacteria were obtained from the root nodules of several leguminous plants gathered from various agricultural locations in the northern part of Iraq to investigate their antibacterial activity. The application of the liquid fermented filtrate medium of the rhizobacteria ER6 isolate demonstrated an inhibitory impact on the pathogenic bacteria Escherichia coli isolate ER51. At the time of testing the antibacterial activity, the average diameter of inhibition was 16 mm. The ER9 isolate exhibited antibiotic activity against the isolates of Klebsiella pneumoniae (ER54), Bacillus cereus (ER53), and Staphylococcus aureus (ER52). A maximum average inhibition zone of 18 mm was observed against Staphylococcus aureus ER52. Of the four isolates, ER38 and ER14 demonstrated the highest mean zone inhibition against the ER53 Bacillus cereus isolate at 28 and 29 mm, respectively. PCR results from rhizobacterial isolates were sent for sequencing. The ER6 isolate and the Enterobacter quasihormaechei strain WCHEs120003 (accession no. NR_180451.1) were 97% similar while the ER9 isolate and Kosakonia oryzendophytica strain REICA_082 (accession No. NR_125586.1) had 98% homology. The ER14 isolate's homology percentage with Cronobacter turicensis z3032 (accession No. NR_102802.1) was 99% while that between Kosakonia pseudosacchari strain JM-387 (accession No. NR_135211.1) and ER38 was 98%. The findings show that the rhizobacteria ER6 isolate has potential antimicrobial activity against the three studied pathogenic isolates E. coli ER51, B. cereus ER53 and K. pneumoniae ER54, respectively