author(s)
Md. Roushan Ali, Md. Faruk Hasan, Rizwoana Sharmin Lia, Afrin Akter, Mst. Sabina Eyesmin Sumi, Md. Firose Hossain, SM Zia Hasan, Dr. Md. Asadul Islam, Dr. Md. Khalekuzzaman and Dr. Biswanath Sikdar

abstract
The present investigation was designed to isolate and characterize of Xanthomonas axonopodis pv. citri bacteria in Citrus aurantifolia canker disease and evaluation of its antibiotic susceptibility, antibacterial sensitivity and antagonistic activity. Isolated bacterium was characterized by different biochemical test method. Isolated bacterium was found to be gram negative, small size, rod shaped, motile and pink in color. The biochemical tests showed catalase positive, glucose fermenting, lactose non-fermenting and urease test negative. The antibiotic susceptibility, antimicrobial sensitivity and antagonistic activity were determined by disc diffusion method. Gentamycin showed highest 21.0±0.0mm diameter of zone of inhibition against the isolated bacteria. Allium sativum extract showed highest 19.9±0.4mm diameter of zone of inhibition against the isolated bacteria. The highest antagonistic activity was found to be 17.4±0.3mm diameter of zone of inhibition by soil borne bacteria X against the isolated bacteria. The present study would be helpful for biological control of canker disease.