donny, on 01 December 2011 - 07:31 PM, said:
I've been screening mutant libraries and the libraries keep ending up with the same mutant. I made new libraries and the same thing happened again. I suspect 2 sources : reused electroporation cuvette and aerosol during pipetting. I can easily use new cuvettes but I seriously doubt it is the main cause because I've tried transforming cells in the old cuvettes just to test the sterility and got no colony. Moreover, I exposed the cuvettes to UV at 300nm over the illuminator for DNA gel for 10min before using them. I guess that should damage whatever residual DNA that could have transformed. I'm thinking if aerosol generated by pipetting during cell preparation could have caused the cross-contamination. However, instinctively, I find it hard to believe the (invisible) aerosol could cause such extensive contamination. Has anyone experienced cross-contamination due to aerosol generated by pipetting?
Samplers are the main source for every contamination, did you used filters, or not?