Hello: WRT extracting phage DNA. Does the Bio101 kit you are using have a Geneclean-like step? That is, a glassmilk binding step? If so, you may be getting shearing of the bound DNA, if it is bound to more than one glass particle at a time. Shearing may also become a problem when doing extractions in which vigorous agitation (e.g. vortexing) is used. Daniel Kim