Operational and nutritional factors have been studied for the
production of MCE by B. subtilis (natto) Takahashi, a ready available
commercial natto starter. Remarkable milk-clotting activity
(685.7 SU/ml or 12,000 SU/g) can be obtained when the bacteria
was cultivated in the medium containing sucrose (50 g/L),
NaCl (10 g/L), MgSO4·7H2O (0.5 g/L), NaH2PO4·2H2O (3 g/L) and
NaHPO4·12H2O (3 g/L) at pH 6 and 37 ◦C with shaking at 175 rpm
for 1 day