Genomic DNA isolation
Genomic DNA extraction was done according to the method by Ausubel et al.(10).About 1.5 ml ot the bacterial culture was decanted into a sterile eppendorf tube and was centrifuged for 1 minute,at 10000 rpm. The supernatant was decanted completely and the pellet was resuspended in 700 ml Glucose-EDTA-Tris-HCL buffer. Subsequently,50 ml of 10% sodium dodecyl sulphate and 5 ml of 20 mg ml-1 proteinase K were added to the suspension and the cells were lysed for 20 minutes at 60C in a water bath shaker. After the incubation, 500 ml of Phenol-Cheoroform-Isoamyl Alcohol mixture were added and mixed gently for 5 minutes. The mixture was centrifuged for 1 minute at 12000 rpm. About 200 ml of the aqueous upper layer was collected in an eppendorf tube and then 200 ml of 3 M sodium acetate and 800 ml of isopropanol were added. The precipitated DNA was recovered by centrifugation for 10 minutes at 12000 rpm. The pellet was washed with 600 ml of 70% ethanol. After centrifuging for 10 minutes at 12000 rpm the pellet was dried at room temperature for 30 minnutes. The dried pellet was resuspended in 50 ml of sterile water and used immediately for PCR analysis.