To investigate the effect of nitrogen sources on the MCE production,
experiments were carried out with three different inorganic
nitrogen sources, namely sodium nitrate (NaNO3), ammonium
nitrate (NH4 NO3) and ammonium chloride (NH4Cl). The S-medium
with the presence or absence of soybean (10 g/L) was further supplemented
with various nitrogen sources at 0.5% level. The bacteria
were incubated at 37 ◦C with shaking at 175 rpm for 24 h. The
results are shown in Table 2. Accordingly, it is seen that the addition
of various inorganic nitrogen sources to the medium with
Fig. 1. Effects of soybean amount on milk-clotting activities in liquid-state fermentation
of Bacillus subtilis (natto) Takahashi in 24 h of cultivation.
or without the presence of soybean decreased the production of
milk-clotting activities. I