BIOCHEMICAL PROFILING OF THE COTTON BACTERIAL BLIGHT PATHOGEN: A COMPARATIVE ANALYSIS

Abstract

Bacterial blight, caused by Xanthomonas citri pv. malvacearum (Xcm), is a major disease affecting cotton production in Pakistan. Effective management of this disease depends on a thorough understanding of the pathogen’s characteristics. In the present study, Xcm was isolated from infected cotton samples collected in the Bahawalpur region and subsequently purified. Identification was performed through morphological, biochemical, and cultural analyses.

Biochemical characterization showed that the isolates were positive for potassium hydroxide (KOH), catalase activity, oxidative–fermentative (OF) reaction, urease activity, starch hydrolysis, citrate utilization, methyl red, Voges–Proskauer, and casein hydrolysis tests, while they were negative for Gram staining, indole production, and arginine dihydrolase activity.

Cultural observations revealed the formation of mucoid, convex colonies with yellow to orange pigmentation on nutrient agar. On yeast extract dextrose calcium carbonate (YDCA) medium, colonies appeared flattened or slightly raised, mucoid, and ranged in color from bright to pale yellow.

These findings provide valuable insights for accurate identification of Xcm and support further in vitro evaluation of management strategies for controlling bacterial blight in cotton.