How to extract genomic DNA beyond 150KB? - (Mar/09/2006 )

I need to extract bacteria genomic DNA in order to constract cosmid libraries,the genomic DNA must be ~150 kb before digestion.would you like to give a good protocol to extract genomic DNA?
Thank you. Email address: tezhao@126.com, tezhao@gmail.com

I would look on the methods portion of this website (POL home)