Enzyme kits and libraries

A kit comprising at least one container containing a mixture of enzymes, wherein said enzymes are obtained by culturing a gene expression library, comprising a pool of expression constructs, each expression construct comprising a vector containing one or more cDNA or genomic DNA fragments, wherein the cDNA or genomic DNA fragments in the pool of expression constructs are derived from a plurality of species of uncultured donor microorganisms, and wherein the cDNA or genomic DNA fagments are each operably-associated with one or more regulatory regions that drives expression of genes encoded by the cDNA or genomic DNA fragments in an appropriate host organism, wherein the enzyme is selected from the group consisting of oxidoreductase, transferase, hydrolase, lyase, isomerase, and ligase activity.