著者

北原 覺雄 村田 卯一

出版者

公益社団法人日本生物工学会

雑誌

醗酵工學雑誌 (ISSN:03675963)

巻号頁・発行日

vol.31, no.3, pp.90-98, 1953-03-15

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Experiments were carried out on the diastase systems of 124 strains of aspergilli, including 120 strains of flavus-Oryzae; 3 strains of awamori; and 1 strain of kawachii, isolated from commercial 'Tane-koji'-the starters for koji-making.1) Characteristics of flavus-Oryzae a) Generally, flavus-Oryzae is far superior to any other species of mold in α-amylase activity. And this will be the very reason what made possible the peculiar procedure of sake brewing, starting from the mash containing as high as 35% of starch.b) The difference of α-amylase activities, lying between the extreme strains of flavus-Oryzae, has been indicated as the ratio of 8 to 1,when compared with the time for disappearance of iodine color. Strains comparatively rich in α-amylase are used for industries manufacturing such as sake and spirits, while poorer strains are used for making 'shoyu'. Consequently, it appears probable that protease is inversely distributed among the strains against α-amylase. However, this problem is left for future studies.c) Maltase power of flavus-Oryzae is generally inferior to other mold species, but there exist several exceptional strains having quite strong maltase activities.d) No cor-relation can be seen between the activities of α-amylase and maltase, among the strains of flavus-Oryzae.e) Within the present exprimental conditions, maltase activity reveals maximum at the koji of 38 hrs incubation, and gradually declines by prolonged culture, but on the other hand α-amylase activity receives almost no effect by the age of koji. This functional change of maltase activity will be considered as one of the remarkable characteristics of flavus-Oryzae, since such phenomenon can hardly be seen in other species.(2) A simple enzyme-analysis a) Wheat-bran culture, which contains solely α-amylase, is readily obtainable when a voluntary strain of comparatively weak in maltase activity was cultured for eight days. This is an application of the phenomenon mentioned in the preceding article (e).b) Applying the treatment for eliminating α-amylase, it has been confirmed that flavus-Oryzae possesses an amylase of β-type. The β-amylase is most active when a strain having comparatively strong maltase activity was cultured for 38 hrs.c) At present, authors feel no inconsistency towards KITANO'S view of 'Taka-maltase', considering that β-typed amylase of flavus-Oryzae is combined with maltase activity, because the raise and fall of the β-amylase activity are quite parallel with those of maltase. Consequently, Taka-maltase (Asp. Oryzae) appears to be quite alike, even if it should not be identical. with gluc amylase (Rh. delemar) or amylo-glucosidase (Asp. niger), however, all of them have a question whether they can be made free from maltase, like γ-amylase.