PLASMID STABILITY AND MAINTENANCE OF COPY NUMBER USING NATURAL MARKER

Present study was conducted to study the plasmid stability with the help of natural plasmid isolated from the bacteria which lodges the ink gland of the sea squid and emits bioluminescence. Isolated bacterial strain was identified by using 16srRNA sequencing and its plasmid DNA was used for the experimental studies. The plasmid is found to be responsible for the bioluminescence. The stability of this plasmid was studied in shake flask method using the different sugar sources (Glucose, Sucrose, Lactose and Maltose) as fermenting medium. The cultures were incubated at different time intervals in which the plasmid stability was inferred by deducing the Bacterial Growth curve. The optical densities were read out and the growth pattern was obtained. Along with the growth curve, the transformation efficiency and CFUs (Colony forming Unit) was calculated for individual volumes of bacterial cultures. The transformation efficiency was found to be increased after every 12 hrs of incubation which indicated the improved plasmid stability. The effect of carbon sources was suggestively detected in the growth curve. Among the four sources of carbon, addition of Glucose exhibited highest Optical density value and inferred the enhancement in Plasmid stability.