Prominent Occurrence of Pseudomonas species as Endophytes in Hultholia mimosoides with Potential Antibacterial Activity

ABSTRACT: Endophytic bacteria found in medicinal plants are emerging as a possible source of novel bioactive chemicals with therapeutic promise, an investigation on the endophyte bacteria from the therapeutically valuable plant Hultholia mimosoides. Resulted in the molecular identification of potential endophyte bacteria belonging to the genus Pseudomonas spp and Bacillus subtilis. The 16S rRNA sequencing revealed a diverse group of bacteria, predominantly from the Pseudomonas genus, including Pseudomonas citronellolis PP843580, Pseudomonas mendocina PQ056994, and Pseudomonas aeruginosa PQ056923, alongside Bacillus subtilis PP795019. Ethyl acetate extracts of these strains were tested against six test pathogenic bacterial strains, including Escherichia coli ATCC8739, Salmonella typhimurium ATCC23564, Staphylococcus aureus ATCC23565, Klebsiella pneumonia ATCC9621, Bacillus cereus ATCC10876, and Proteus vulgaris ATCC13315. The well-diffusion assay revealed significant antimicrobial activity, particularly by Pseudomonas putida PP907914, which showed notable activity against all the test pathogens. Other strains also exhibited broad-spectrum activity, highlighting their potential to combat antibiotic-resistant pathogens. Among these, Pseudomonas citronellolis PP843580, has demonstrated a significant zone of inhibition with 16 mm against E. coli ATCC8739. These findings emphasize the symbiotic relationship between medicinal plants and their endophytic bacteria as a valuable source of novel bioactive compounds. The current study highlights the potential of endophytes as a source of medicine. Further exploration of the bioactive metabolites from these bacterial isolates could lead to the development of innovative therapeutics.