Antibacterial potential of Emblica officinalis endophytes against multidrug-resistant avian pathogenic Escherichia coli (APEC)

Colibacillosis remains a major threat to the poultry industry of Pakistan, leading to significant economic losses. The disease is caused by avian pathogenic Escherichia coli (APEC), which induces multiple complications leading to prolonged and irrational antibiotic use. This is resulting in the emergence of multidrug-resistant APEC strains, highlighting the urgent need for alternative control strategies. Medicinal plants and their endophytic microbiota represent promising sources of bioactive compounds with antimicrobial potential, as they have co-evolved with their host plants and often mimic or enhance host defense mechanisms. In this study, bacterial endophytes were isolated from Emblica officinalis (Amla), a medicinal plant widely used in traditional medicine, and their extracts were tested for antibacterial activity against pre-confirmed APEC strains using the agar well diffusion method. To provide a comparative analysis, fruit extracts of E. officinalis were also evaluated for antibacterial activity under the same conditions. The endophytic extracts exhibited significantly stronger antibacterial activity (28 mm inhibition zone) than the fruit extracts (16 mm inhibition zone), indicating the superior potency of endophyte-derived metabolites. Partial purification via thin layer chromatography (TLC) confirmed distinct active components responsible for this activity. These findings suggest E. officinalis endophytes as valuable candidates for alternative, sustainable approaches against antibiotic-resistant poultry pathogens.