Biotin synthase of Bacillus subtilis shows less reactivity than that of Escherichia coli in in vitro reaction systems

The biotin synthases of Bacillus subtilis and Escherichia coli were compared in a physiological reduction system using cell-free extracts and in a artificial reduction system using photo-reduced deazariboflavin. The biotin synthase of B. subtilis was less active than that of E. coli in both reaction systems and showed at least ten-fold less biotin-forming activity than that of E. coli in the artificial reduction system. The physiological reduction system using the biotin synthases and cell-free extracts of B. subtilis and E. coli showed species specificity. The results suggest that the activity of the physiological reduction system of B. subtilisis weaker than that of E. coli. Addition of excess dethiobiotin inhibited biotin formation by growing cells of B. subtilis, but not by E. coli.