抄録
Bacillus natto IAM 1212 produces a-amylase by about 5 times as much as Bacillus subtilis Marburg strain, α-amylase of which is more thermostable and moves more slowly to anode at pH 8.3 than that of B. natto. DNA of B, natto could induce transformation in B. subtilis cells of many genetic charactors including amylase productivity. Genetic analyses of the transformants that acquired high amylase productivity revealed that a gene regulating a-amylase synthesis participates in the a-amylase-producing system of B, subtilis and this regulator gene (amy R) is closely linked to the a-amylase structural gene. The amyR gene is linked also to the aronG gene which has been reported to be linked to α-amylase-structural gene by S. Yuki. α-Amylases produced by parents (B, subtilis 6160 and B. natto IAM 1212) and two transformants (NA64 and NA20) were purified, their properties were investigated and their molecular weights were estimated to be 55, 000, 34, 000, 55, 000 and 42, 000, respectively. Thus, it was suggested that the two transformants produced a-amylases with hybrid charactor of their parents amylases. Immunological properties were all alike, but their substrate specificities were different. a-Amylases of 6160 and NA64 could hydrolyse maltotriose while those of B. natto and NA20 could not. Mutants which had a genetic charactor to increase the production of both a-amylase and protease simultaneously, were isolated from a transformable strain of B, subtilis 6160 by NTG treatment. This mutation seems to have occurred at a single gene of the bacterial chromosome and was not linked to aro116. When this mutation and a-amylase regulator gene amyRh, (amyR of B, natto) coexisted in one cell, their synergistic effect on extra cellular α-amylase production was observed. Thus the level of α-amylase in culture medium of B. subtilis was elevated from 11 unit/ml to 140 unit/ml.
