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genomic DNA extraction: up to 50kb? - genomic DNA isolation (Dec/06/2010 )

Hi, I am going to clone a gene of interest from bacterial genomic DNA. So the first thing is to isolate the genomic DNA using a kit. I found most kits said they extracted genomic DNA up to 50kb. But I know the genome of the bacterial is kinda 5000kb. Are the DNA extracted by the kits actually smears? are these genomic DNA isolated linearized for PCR amplification? please comment me or correct me.

Thanks a lot!


All the kits will produce sheared genomic DNA. Usually this is not a problem, since you will PCR from it, and there will be linear fragments longer than a typical pcr reaction product. Yes, you will likely see a smear on a gel (but the gel can't usually distinguish 20Kb from 50Kb from 5000 Kb fragments).