Abstract
The author selected 198 strong acid-producing strains (1.0_??_1.4N in mash, including physiological acidic nitrogen-source) from 1, 928 strains of black Aspergilli, most of which were isolated from samples collected in almost whole districts of Japan, and using, these strains studied on -citric acid fermentation which have been applied to industrial production of citric acid from 1937 to 1948. The author carried out mycological studies on the representative strong strains and according to the SAKAGUHI's key for the classification of the “Kuro-Koji” mold(1), found that most of them (Group I) belonged to Aspergillus saitoi SAKAGUCHI, II7_UKA et YAMAZAKI and a few of them (Group II) to Aspergillus saitoi var. R-16 SAKAGUCHI, IIZUKA, et YAMAZAKI.
Characteristics are as fsllows:
1. Shape of the organs: same as black species of SAKAGUCHI's “Kuro-Koji” mold; especially the surfaces of the conidial wall are provided densely with fine aculeate processes, which are same as A. saitoi and A. usamii; colour of colonies are Fuscous Black XLVI-Blackish Brown (3) XLV (sometimes more brownish by group 11); sclerotia (+) (Group I), (-) (Group II); perithecia (-).
2. Dimension of the organs; see Table 1.
3. Abundant growth and good sporulation on Koji-agar, potato slice, bread, cooked rice, PFEFFER-oryzanin-agar and CZAPEK-agar. (On some media by Group II colonies are somewhat brownish.
4. Thermal death point: 55°, 30 min.
5. Optimum temperature 35° for growth, 30° for sporulation, time for sporulation 21 hrs.
6. Optimum pH for growth: 2.6_??_5.0 (Group 1), 2.6_??_4.4 (Group II).
7. Gelatin liquefaction PFEFFER-oryzanin gelatin (+); tap-water gelatin (+) (Group I), (-) (Group II).
8. Coagulation and digestion of milk (+).
9. Fermentation and assimilation of carbohydrates: see Table 2.
10. Assimilation of N-materials: see Table 3; nitrite is not assimilated.
11. Acid-producing power: very strong.
12. Saccharifying power: strong.
