1. This paper deals with the results of studies on the effect of sulphuric acid solutions upon the sclerotial germination of Sclerotinia trifoliorum Eriks. 2. In 5 and 10per cent sulphuric acid solutions, 1 and 3 hours treatments can not be expected to prevent sclerotial germination, but 4, 5, 7 and 10 hours treatments can be expected to sterilize sclerotia. 3. According to the concentration of sulphuric acid solution and the time of treatment, the treated parental sclerotia formed secondary small sclerotia of three types. In solutions higher than 20per cent, there is a tendency for the increase of secondary sclerotial formation as concentration increases. 4. Decay of the rind-tissue of sclerotia occurs in higher percentages as concentration increases. The injured sclerotia do not germinate directly, but form secondary sclerotia which germinate by apothecial stalks. 5. The authors considered two types of mechanisms for the sterilizing action of sulphuric acid solution: by means of penetration and of corrosion. Sulphuric acid acts mainly penetration in dilute solution, and by corrosion in strong ones.
1. Erwinia carotovora produces two kinds of pectin depolymerases (DP), one having the optimum pH at about 8.5 (DPa) and the other at about pH 4.0 (DPb). 2. The initial pH of culture medium affected the production of DP, i. e., in synthetic medium A containing pectin (see Table 2), both DP, especially DPb, were scarcely produced in case the initial pH was 5.5 or 5.8, but abundantly in case that was above 6.0. In the former case, pH shift toward 4.0∼4.5 and its stagnation at this level for a long time during the culture period were the main factors which depressed the enzyme secretion (see Table 1 and Fig. 1). 3. In beef extract broth DPa was secreted to varying degrees of activity according to the isolates used, whereas DPb was scarcely secreted irrespective of isolates, even in the presence of pectin. Addition of 0.5per cent peptone to the synthetic medium A stimulated the secretion of DPa at the primary stage of growth, whereas somewhat depressed the secretion of DPb. Addition of 0.5per cent mono-sodium glutamate to the synthetic medium A stimulated the secretion of both enzymes to a great extent. In media containing glucose as the sole carbon source, DPb was scarcely produced, whereas DPa was secreted to a relatively high degree. The media used by Echandi et al. (1957) and by Wood (1955) in their studies on pectolytic enzymes were unfavorable for the production of DPb; especially in the latter no DPb activity was detected. DPa was usually secreted faster than DPb. In the most suitable medium for depolymerase productions, DPa was secreted rapidly from the primary stage of growth, reaching its maximum accumulation after 48 hours. DPb was secreted much more slowly, reaching its maximum accumulation on 3rd to 8th day after inoculation, the date varying according to the isolates used. 4. Both depolymerases, especially DPb, were scarcely secreted in media of low salt concentrations, even if it contained enough pectin as the substrate. This may be due to the pH shift toward 4.0∼4.5 because of the low buffering effect (see Table 4 and Fig. 3). 5. Both depolymerases were produced more abundantly in flask culture than in test tube culture, suggesting that the larger was the area of air contact with the medium surface the larger was the amount of enzymes produced. This effect of air was not so intense as in the case of PME production previously reported (Table 5 and Fig. 4). 6. The activity of both depolymerases, after 5 day-incubation in the synthetic medium A, differed according to the isolates used (see Table 6).
The present paper deals with the production of indoleacetic acid by Sclerophthora macrospora in synthetic culture media (modified Richards' solution). Indoleacetic acid was extracted from the culture filtrate with ether, and was determined by the Salkowski's color reaction, paper-chromatography, Avena straight growth test, and also by the ultraviolet absorption. As much as 0.017mg of Indoleacetic acid per 100ml of culture filtrate during 10 days culture was produced in modified Richards' solution with no addition of L-tryptophan. It increased to 0.672mg, when 0.01per cent L-tryptophan was added to the solution. When 0.1per cent L-tryptophan was added, 3.04mg of indoleacetic acid per 100ml culture filtrate was obtained. Judging from the above results, it is considered that S. macrospora has a complete enzyme system to metabolize inorganic nitrogen to indoleacetic acid.