Incubate the culture of the strain E. coli DH5α carrying different construct in M9 minimal medium, at 37 °C and 180 rpm. Subculture the bacterium every 12hr and collect sample every 24hr, make serial dilution of the cell suspension, including a 10-7, 10-8 and 10-9 dilution. Plate these dilutions on the LB agar plates without antibiotic. Incubate the plates overnight in 37℃ and stamp transfer colonies to agar plates with selection pressure. The ratio of colonies on the plates represents the plasmid retention rate. By this way, we can know the plasmid loss rate of different construct versus time.

We cooperate with NYMU-Taipei to finish the experiment. The result can be found on their webpage.

https://2012.igem.org/Team:NYMU-Taipei/ymico1.html