TAMZIDA SHAMIM ASHRAFEE, MD. JAHANGIR ALAM, RAJESH BARUA, ZOBADA KANAK KHAN, MD. JAHANGIR ALAM AND MD. ABDULLAH AL MAMUN
Abstract
Xanthomonas campestris is a gram negative, aerobic, rod shaped bacteria commonly known for causing important plant diseases such as black rot, citrus canker etc. In the present study, we analyzed the banding patterns of plasmids of X. campestris and also isolated the genomic DNA in a rapid, cost effective method. Twenty three bacteria isolated from twenty plant sources were identified through different biochemical tests include gram staining, egg yolk reaction test, gelatin liquefaction, starch hydrolysis, indole test, citrate utilization test, sugar fermentation test, urease, catalase and 3% KOH solubility test. Then hypersensitivity test, antibiogram and herbal sensitivity tests were conducted for further investigation. In hypersensitivity test, eleven isolates were positive and caused infection on host plant leaves. 100% isolates were ampicillin resistant, 8% and 13 % were susceptible to tetracycline and gentamycin respectively as well as 100% were sensitive to ciprofloxacin and streptomycin. In herbal sensitivity test, three isolates were highly sensitive to garlic extracts and other six isolates showed poor zone of inhibition. All isolates were resistant to alovera, onion and centella extracts. The average larger plasmid sizes were ranged from 24 to 30 kb and small sized plasmids were ranged from 0.5 to 5 kb. 6 to 23 kb sized plasmids were not found which are rare in this species. The genomic DNA showed four bands sized 1, 2.5, 3.5, 25 kb.