SECRETION OF STREPTAVIDIN FROM BACILLUS-SUBTILIS

Streptavidin is an extracellular tetrameric protein produced by Strept omyces avidinii. A series of hybrid gene fusions consisting of Bacillu s signal peptide coding regions fused to the mature streptavidin seque nce were constructed. B. subtilis strains harboring these plasmids acc umulate a tetrameric streptavidin in the growth medium. The properties of the streptavidin produced by B. subtilis are similar to those of t he streptavidin produced by S. avidinii. B. subtilis strains carrying the various fusions can be grown to a high cell density in a biotin-fr ee medium. Thus, B. subtilis represents an alternate host system for t he production of streptavidin.