海水細菌Vibrio purpureusの寒天分解酵素に関する研究

Abstract

As for the agar-decomposing enzyme, previous works (Gran, 1902; Oshima, 1931; Mori, 19-39) have merely been concerned with the existence of such enzyme in some kinds of organisms, and, therefore, our knowledges of this matter are far from being satisfactorily unders tood. Such being the case, the present author attempted this study from various standpoints in order to clearly made out chemical behaviors of this enzyme in some extent. In the first place, factors affecting the activity of the enzyme of a kind of marine bacteria Vibrio purpureus were preliminarily studied in the following procedure: 1) A semifluid medium, 0.2 per cent agar, was incubated at 25°C after being inoculated with an active culture of Vibrio purpureus. Afer 96 hours, incubation the culture was filtered by Chamberand's Filter and it was used as the crude preparation of the enzyme. 2) The effects of temperature and pH value on the activity of the crude enzyme preparation described above were studied by estimating the amount of reducing sugar produced or by measuring the decreasing rate of relative viscosity. The results obtained are illustrated in Fig. 1 and Fig. 2. From the data it seems very probable that the optimum temperature is at around 40°C and the optimum pH value is approximately 6.0 3) The decomposing process of agar-agar by the crude enzyme preparation was observed by the following method: Reducing sugar and relative viscosity of the reaction mixture (0.3 per cent agar solution 40 Occ+McIlvaine's buffer solution of pH 6.0 200cc) were determined after various period of reaction at 40°C. The results obtained are shown in Fig. 3. The velocity constant of the reacton calculated from this results by using the monomolecular equation was shown in Table I. From this table it is obvious that the rate process obeys the monomolecular reaction within a certain limited range. 4) The effect of NaCI upon the activity of the enzyme solution which had previously been dialysed in running water for five days dy using the collodion membrane was observed by the usual method. The results obtained are illustrated in Fig. 4. From the data it was found that the optimum concentration of NaCI for the actvity of the enzyme is nearly 3.5 per cent.