Isolation and Purification of Dna

IMPORTANT NOTE: The smallest amount of contamination of DNA preparations by recombinant phages or plasmids can be disastrous. Many person-years have been wasted reisolating previously cloned sequences that contaminated preparations of DNA used to create recombinant DNA libraries and many researchers have been embarrassed to find that the “extra” genes they found on their Southern blots were actually contaminating plasmid DNA. All materials used for preparation of plasmid or phage DNA should be kept separate from those used for preparation of genomic DNA, and disposable items should be used wherever possible. Particular care should be taken to avoid contamination of commonly used rotors.