Summary A metagenome expression library of bulk DNA extracted from the rumen content of a dairy cow was established in a phage lambda vector and activity‐based screening employed to explore the functional diversity of the microbial flora. Twenty‐two clones specifying distinct hydrolytic activities (12 esterases, nine endo‐β‐1,4‐glucanases and one cyclodextrinase) were identified in the library and characterized. Sequence analy...