Abstract
1. Cooked soybean was fermented for about a week by Bacillus megatherium 88-3, D-28 and D-28a; and compared with the cooked soybean which was not fermented, this fermented soybean showed much increase in vitamin $B_{12}$ and $B_2$, while vitamin $B_1$ decreased. 2. In the process of fermenting the cooked soybean, Bacillus megatherium, 88-3 is the bacteria which produces brown pigment; and Bacillus megatherium D-28 and D-28a is the bacteria which produces yellow pigment. 3. In weight, fermented soybean-fed rat showed more increase than the unfermented soybean-fed rat. But the growth of the rat fed with Bacillus megatherium 88-3 fermented soybean was not good. Probably, this phenomenon came from the trouble in rat's metabolism by brown pigment. 4. In food efficiency, Bacillus megatherium D-28a is 4.3% lower than Bacillus megatherium B-938, but it is 17.l% higher than the unfermented cooked soybean. Bacillus megatherium 88-3, which is 47.1% lower in food efficiency than the unfermented cooked soybean, has been found "not good" in the growth of rat.th of rat.