Abstract
Soybeans were boiled, inoculated with Bacillus natto IAM 1114, and incubated at 37 °C. A viscous substance (VS) fraction was extracted with water and the extract was centrifuged to obtain a supernatant. Lyophilization of the supernatant afforded a powdered VS product which was then submitted to various analyses. The amount of VS increased with incubation and, after 48 hr, led to occupy a 2% portion of the Natto. A crude protein content of VS also increased from 60 to 80% during incubation. At any stages of incubation, glutamic acid occurring in VS was found to be in a polypeptide form and the D-isomer proportion of the glutamic acid was 22.3 % at 24 hr and 77.9% at 48 hr. However, the polyglutamic acid content of the crude protein was not more than 20%. Free amino acids also occurred in VS and their content increased from 10 to 30% during incubation. Despite of that, free glutamic acid rather showed a relatively slow rate of increase.
