strepogenin

strepo·gen·in .strep-ə-'jen-ən n a biologically active principle, characteristic chemical structure, or amino acid content attributed esp. formerly to various proteins, peptides, or mixtures of them to account for their ability to stimulate growth of various microorganisms and esp. one of the genus Lactobacillus (L. casei)

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strepo·gen·in (strep″o-jenґin) a factor present in casein and certain other proteins which is essential to optimal growth of animals.