Isolation of Plasmid Dna from Bacteria Associated With Ulcerative Disease in <i>Channa punctatus</i>

Abstract

Ulcerative disease has been prevalent particularly in snake head and catfishes. A number of virulent bacteria are associated with this disease. A variety of important properties viz., virulent determinants, antimicrobial resistance, etc. of the pathogenic bacteria that enabled them to thrive better in the adverse environment, have been proven to be plasmid encoded. Keeping in mind the importance of plasmid DNA, this study has been undertaken. Plasmid DNA was isolated by alkaline lysis method from the cultured bacteria associated with ulcerative disease of snake head, Channa punctatus. Isolation of plasmid DNA followed by agarose gel electrophoresis analysis have revealed the presence of a single plasmid DNA in the cultured microbe which comigrated with 23 kb DNA fragment of the lambda DNA digested by Hind III. The cultured microbe was characterised as: Gram-negative motile rod, catalase-positive, oxidase-negative, indole-negative, non-HS producing, lactose fermenting, acid and gas produced from glucose, methyl red-negative, Voges Prauskauer-positive and urea negative. It seems from the above mentioned biochemical as well as morphological characteristics that the cultured microbe was very similar to Enterobacter and Citrobacter.