All the Acetobacter xylinum strains examined, including the cellulose-forming and celluloseless ones, were found to have the ubiquinone system comprising Q-10 and were discriminated in this respect from any other members of the genus Acetobacter, especially of the mesoxydans group. The significance of difference in the quinone system is discussed from the taxonomic point of view. It is probable that these Acetobacter strains having such a Q-10 system should be re-accepted as a separatespecies A. xylinum from A. aceti, whether they produce the cellulosic leathery pellicles or not.
Fourty-three cultures of apiculate yeasts were examined for the Co-Q system, which belong to the genera Nadsonia, Saccharomycodes, Wickerhamia, and Hanseniaspora and its imperfect counterpart of Kloeckera. All the species of these genera were found to have the Q-6 system except for the only species of the genus Wickerhamia (Q-9). The results obtained are discussed in connection with other criteria such as PMR spectra of cell wall polysaccharides, DNA base composition, and serological characteristics. Our method is described as a criterion for grouping yeasts and yeast-like organisms.
The function of CO2-related growth-promoting effect in the orange-colored Streptococcus bovis was investigated. In the defined medium, CO2 requirement was very large compared with that in natural media. Most of 14CO2 incorporated was detected in the protein part. On the other hand, in the Polypepton-yeast extract medium, 14CO2 incorporation was extremely small and about 40% of the incorporated 14CO2 was found in the lipid part. Though S. bovis required only biotin as an essential factor among the vitamins, in the Polypepton medium, some of unsaturated fatty acids and oleate-containing compounds could replace not only biotin but also CO2 requirement, whereas, in the synthetic medium, these compounds could not replace CO2 requirement. This result suggests that CO2 takes part in synthesizing not only amino acids but also fatty acids. S. bovis is sensitive to oxygen, but CO2 or unsaturated fatty acids can be replaced by O2 in natural media.
Effects of some physical and chemical factors on the germination of akinetes of Anabaena cylindrica were studied. The akinetes placed in an inorganic medium germinated, after a certain lag period, in the light but not in the dark. At temperatures above 35°, no germination occurred even in the light. This germination was inhibited by 3, 4-dichlorophenyldimethylurea (DCMU), an inhibitor of photosynthesis. The optimum pH for germination in the inorganic medium was in the range of 7.0 to 8.0. Oxygen was essential for the germination of akinetes. Among various compounds tested, acetate was most effective in stimulating the germination. Acetate was easily taken up by akinetes, but it did not affect the respiration. Radioactivity of the incorporated 14C-acetate was mainly recovered in ethanol-soluble fraction, especially in glutamate and leucine.
One hundred and thirty-one cultures of the genera Debaryomyces, Saccharomyces, Kluyveromyces, Endomycopsis, and Saccharomycopsis were examined for the Co-Q system. The genus Debaryomyces was divided into two groups; Q-6 in the intense fermentors of D. globosus, D. franciscae, and D. nilsonii, and Q-9 in the weak fermentors such as D. hansenii, D. cantarellii, and D. tamarii. The genera Saccharomyces and Kluyveromyces were characterized by the only system comprising Q-6. The genus Endomycopsis represented three types of Co-Q system; Q-7 in E. bispora, E. platypodis, and E. monospora, Q-8 in most of the species in this genus, E. capsularis, E. fibuligera, E. vini, E. burtonii, E. javanensis, and E. selenospora, and Q-9 in E. ovetensis and E. lipolytica. Saccharomycopsissynnaedendra gave the Q-8 system. Discussions are made from the taxonomic point of view, especially on the yeasts and yeast-like organisms possessing the same system of Co-Q as found in the genera Hansenula and Pichia (Q-7, Q-8, and Q-9).