are amplified to complete the normalization process for example samples can be amplified using pcr amplification protocols such as those described by ko et al ko 1990b ko 1990a takahashi 1994 or more preferably long pcr protocols such as those described by barnes 1994 or cheng 1994 normalization can be performed directly or steps can also be taken to reduce the complexity of the nucleic acid pools prior to the normalization process such reduction in complexity can be beneficial in recovering nucleic acid from the poorly represented organisms the microorganisms from which the libraries may be prepared include prokaryotic microorganisms such as eubacteria and archaebacteria and lower eukaryotic microorganisms such as fungi some algae and protozoa the microorganisms may be cultured microorganisms or uncultured microorganisms obtained from environmental samples and such microorganisms may be extremophiles such as thermophiles hyperthermophiles psychrophiles psychrotrophs etc as indicated above the library may be produced from environmental samples in which case dna may be recovered without culturing of an organism or the dna may be recovered from a cultured organism sources of microorganism dna as a starting material library from which target dna is obtained are particularly contemplated to include environmental samples such as microbial samples obtained from arctic and antarctic ice water or permafrost sources materials of volcanic origin materials from soil or plant sources in tropical areas etc thus for example genomic dna may be recovered from either a culturable or non.