Production of streptavidin in a synthetic medium

A simple, inexpensive procedure for producing streptavidin has been described. The biotin-binding protein was produced by growing Streptomyces avidinii in a synthetic liquid culture medium containing L-asparagine as the sole nitrogen source. With this procedure, extraneous proteinaceous substances inherently present in culture media prepared with yeast extract or with peptones were not present to interfere with isolation and purification of streptavidin. When harvested after 7-8 days of incubation, the culture fluid was relatively free of contaminating cell breakdown products. Maximal production of streptavidin (100-120 mg/l) was obtained in 8-10 day cultures. For some applications, the culture fluid can be used directly as a source of streptavidin. Under the same conditions used to grow S. avidinii, 11 other actinomycete strains and 134 eumycetes were found to lack the capacity to produce detectable amounts of an extracellular biotin-binding protein.