Simplified procedure for producing Bacillus subtilis spores for the Guthrie phenylketonuria and other microbiological screening tests.

Bacillus subtilis ATCC 6051 and ATCC 6633 spores used in bacterial inhibition screening assays for genetic metabolism defects in newborn infants were produced by using liquid synthetic replacement sporulation media. These media allowed a high degree of sporulation, as judged by direct cell counts. Sporulation took place within 23 to 27 h with these media. Also, a more rational procedure for selecting the most sensitive clones of these organisms to the various inhibitors used in the microbiological screening assays is presented.