In order to obtain new or unique species belonging to Genus Pichia Phaff including those already, reported, which seem to play an important role in solving phylogenetic problem on yeasts, many cltures have been isolated from various kinds of samples sent from abroad. This paper is the first report which deals with three cultures selected from many of fresh isolates mentioned above, for which the authors wish to propose provisionally the name Pichia terricola VAN DER WALT form. α as distinguished from the authentic description in some morphological properties.
The mechanism of the germicidal action of surface active agents was studied. It was observed that surfactants have the following action on intact cells of lactic acid bacteria; (1) accelerate the penetration of lactate into the intact cells, (2) liberate the free amino acids from internal environment, (3) prevent the penetration of glucose and gluconate, which are metabolic sources of energy for the cell. Some remarkable parallelisms between these actions and their germicidal power were observed. When the cells which had changed in the permeability and been unable to grow by binding with CTAB were washed with the oppositely charged surfactant A-1. The permeability of the cells reversed to that of the intact cells and the cells grew again. From these results, it is supposed that the germicidal action of surfactants depends on the action to immediately bind with the cells changing the permeability to unsuitable one for growth. Moreover, anionic surface active agents inhibit lactic dehydrogenase and glucose-6-phosphate dehydrogenase. It seems likely that the germicidal effect of anionics depends not only on the action to change the permeability of the cells but also on the action to denaturate the cell proteins.
A routine method of DNA-mediated transformation is described. Cells of tryptophan dependent strain (No. 160 Sr) of Bacillus subtilis, harvested at an early stationary phase of growth in a glucose minimal medium containing 0.1% yeast extract, are found to be the most competent for transformation (1st culture). When transforming DNA is added to the cells suspended in a fresh medium (2nd culture), transformation occurs linearly with the time lapse after a short lag period. The process of transformation seems independent of cell growth, although the acquisition of competence by the cells is under the control of delicate physiological conditions of the cells which are terminating exponential growth. The yeast extract which is required for the cell growth in the early 2nd culture, when added in excess, lowers the efficiency of transformation. The inhibitory effect of the supplemented medium is eliminated during the growth of cells. The similar inhibition is demonstrated by the addition of nucleotides or amino acids. Physiological control of cell growth in the 1st culture by changing incubation conditions improves the competence. The use of chemostat or the incubation at low temperatures were proved to be an efficient way for obtaining competent cells.
By using monocellular microbes of spherical or quasi-spherical shape, spectrophotometrical studies on turbidity of cell suspension were made with the following results. (1) Commercial spectrometers designed for solution chemistry can be used for approximate measurement of absolute turbidity of microbial suspension. (2) Light scattering spectra of microbial suspensions could thereby be easily obtained making rossible "light scattering analysis" based on the Rayleigh-Gans' and Hart-Montroll's equations. (3) General procedures for obtaining cellular index of refraction, cell volume and cell population were examined in the case of Saccharomycescereuisiae and Chrorella ellipsoidea. (4) "Light scattering analysis" gave some information on biological phenomena such as cell growth and osmosis in liquid culture. (5) Variations of cellular index of refraction caused by volume change of cells explained the apparent inversion of turbidity change observed in osmosis of microbial suspension.
As an aid to ecological research of microorganisms, a differentiation of aerobic bacteria, mainly genus Pseudomonas, was studied. On 28 genera, 114 species and 350 strains of type cultures, cultural and biochemical characteristics, such as assimilation of nitrate, ammonium, glutamate, succinate, glucose, and p-hydroxy-benzoate, reaction to B. C. P. milk, formation of soluble pigments, coloration on nutrient agar slant etc., were tested. The results are shown on Table 3, and the author described a differential key of aerobic bacteria, which illustrated on Table 4. The bacteria belonged to Gram negative group, such as Pseudomonas, Achromobacter, Flavobacterium, Escherichia, Aerobacter etc., are biochemically simple, and would be differentiated by this key. On the other hand, the bacteria of Gram positive, such as Micrococcus, Sarcina, Brevibacterium, Bacillus etc., are nutritionally more complex than that of Gram negative group, and would not easily differentiated by this procedure. Furthermore, some problems of bacterial taxonomy were discussed on the basis of the relationship between bacterial flagellation and biochemical characteristics.