Thiaminase I of Bacillus thiaminolyticus

Abstract Bacillus thiaminolyticus Matsukawa and Misawa grows well on a synthetic medium. Its growth is stimulated by thiamine. Pyrithiamine and oxythiamine are not inhibitory at the concentrations tested. A spectrophotometric assay for thiaminase I activity was developed and used to follow the production and distribution of this enzyme as a function of growth time. Thiaminase I is found predominantly (>90%) outside the cells throughout the entire growth cycle. Thus it appears to be an exoenzyme.