Abstract
“Hama-natto”, a salty fermented soybean product, is produced only in the district around Lake Hamana in Shizuoka Prefecture. There are, however, two methods in producing Hama-natto; one is artificial inoculation with molds belonging to the genus Aspergillus, and the other is natural fermentation by microorganisms living in a koji room. Samples of Hama-natto made by the former method, “Yamaya”; “Horinji, ” and by the latter, “Daifukuji, ” were studied respect to their microflora.
The following results were obtained.
1. There is no marked difference in the number of microorganisms among these three kinds of Hama-natto, except that there are slightly fewer molds in Yamaya and lactic acid bacteria in Horinji than in the others. A large number of molds belonging to Zygomycetes were found in Daifukuji, a natural fermenting Hama-natto.
2. The main microorganisms which are considered to play an important role in producing Hama-natto belong to the A. oryzae type and Storeptococcus and Pediococcus types.
3. A certain mold, which belongs to the A. oryzae type, showed more intensive proteolytic and amylolytic activities than any of the other isolated fungi, such as those of the Zygomycetes type and A. niger.
4. Among A. oryzae type isolates, a mold which forms a dark olive-green colony bearing conidia on the day succeeding inoculation was also found to show strong proteolytic, but not amylolytic activity.
