Provided is a method of screening
gene libraries derived from a mixed
population of organisms for a bioactivity or
biomolecule of interest. The mixed
population of organisms can be a cultured
population or an uncultured population from, for example, the environment. Also provided are methods of screening isolates or enriched populations of organisms, which isolates include a population that is spatially, temporally, or hierarchical, for example, of a particular species,
genus, family, or class of organisms. Identified clones containing a
biomolecule or bioactivity of interest can be further variegated or the
DNA contained in the clone can be variegated to create novel biomolecules or bioactivities of interest.