Microascus doguetii Moreau, M. longirostris Zukal, M. manginii (Loub.) Curzi and Petriella setifera (Schm.) Curzi were recorded for Japan; a Graphium stage was first recognized for P. setifera. On the basis of some new observation made during the study, a revision of the key to the Microascus species was proposed.
The presence of glutamic acid in a suspending medium prevented remarkably the death of various bacteria (21 species, 26 strains) subjected to the process of freeze-drying. Systematic studies were made of the protective effects of 45 compounds related chemically with glutamic acid, and the following compounds were found to be effective for both Gram-positive and -negative organisms tested: aspartic acid, malic acid, cysteic acid, threonine, pyrrolidone- carboxylic acid, acetylglycine, malonic acid, α-methyl-glutamic acid, N-acetyl- glutamic acid, N-dimethyl-glutamic acid and N-dimethyl-aspartic acid. L- and D-forms of glutamic acid showed equally strong protective activities. Aminomalonic acid, tartoronic acid, α-aminopimelic acid, α-ketoglutaric acid and lysine were effective only for Gram-positive bacteria. The protective effect of glutamic acid and related compounds are considered to be of some physicochemical nature and not of a metabolic one. Chemical structures of the effective compounds seems to be characterized by the presence of a hydrogen-bond generating group (e, g., -NH2, >NH, -OH or =O) and two acid groups (e. g., α-COOH and γ-COOH).
Using a strain of Pseudomonas ovalis investigations were made on the oxygen absorption in bubble aeration in the process of gluconic acid fermentation. The oxygen transfer coefficients (kL and km) of liquid films which were assumed to exist around air bubbles and resting cells were estimated. It was difficult to recognize a substantial difference between the values of kL and km; the film coefficient km of the cells was found to be in the range from about 10-1 to 10-3cm/sec, while the value of kL was of the order of 10-2cm/sec corresponding to the bubble diameter of several millimeters. It was also found that the value of km was large compared with the corresponding value (k′m) obtained for the cells without aeration. The ratio k′m/km extended from 0.53 to 0.85, showing no appreciable change according to the rate of aeration ranging from 0.5 to 5.0vvm.
Aspergillus niger and Penicillium urticae were shake-cultured, and the pellets formed were sectioned, stained and examined microscopically. In general, the surface area of these mold pellets were found to be highly basophilic in comparison with the central area. A. niger was unable to form conidia in its pellets, whereas P. urticae formed conidia inside the surface area of the pellets. In this case the conidia were formed directly from hyphae without morphogenetic changes such as penicillus formation. In the central area of these pellets arthrospore-like cells resistant to staining were observed very frequently. When A. niger pellets were treated briefly with 32P-phosphate, they Incorporated 32P actively. Autoradiography of the sections of these pellets showed that 32P was accumulated only on the surface of the pellets. When these pellets were further cultured for 1 day in a ‘cold’ medium, the dark ring in the autoradiogram remained unmoved and the outer area containing no 32P was formed by further growth of the hyphae. This suggests that in the growth process of the pellet there occurred no appreciable translocation of intracellular materials into newly formed hyphae. Cytological features of the differentiation of pellet were compared with those of the surface colony which have been studied in detail in a previous work.
Changes in the fine structure of the conidia-bearing apparatus of Aspergillusniger during the course of its development and degeneration was studied by the technique of ultrathin sectioning followed by electron microscopy. The conidiophore growing from a foot cell is characterized by its fine structure which resembles that of growing hyphae, having an infolded cell membrane connected to other intracytoplasmic membranes and tubules as well as to mitochondria and nuclei. At this stage mitochondria are rather irregular in shape, and nuclei are delimited by double membranes with pores. With the progress of ripening of conidiophore its fine structure becomes more and more granulous; mitochondria appears to be globular, nucleus becomes difficult to discern, and the vesicles are then formed at the tip. At the initial stage of vesicle formation the granulous structure is gradually reorganized into a structure characteristic of growing hyphae, and sterigmata begin to appear from the buds formed on the cell wall of the vesicle. Mitochondria, nuclei and other reticular structures then extrude into the developing sterigmata, which are further septated by the median cell plates developing centripetally from the cell walls of sterigmata. Thus, the formation of primary and secondary sterigmata with organized cytoplasmic structure similar to that of growing hyphae, are completed. The formation of conidia then follows at the apical portion of each secondary sterigma initiated by the inward thickening of the wall. During this process, nucleus, mitochondria and reticular structures in the sterigma appear to move into the apical cell. When the neck stem (thick-wall portion) has been closed completely, a round conidium with a thick exosporium is produced. Vacuolization takes place first in the conidiophore with the formation of a vesicle, and the latter is then vacuolated with the formation of sterigmata, which in turn undergo a similar vacuolization with the formation of conidia.
1. Using M. glutamicus the quantitative analyses were made both on the amino acids excreted into the media and incorporated into the cells at the different levels of biotin. 2. The dual role of biotin in relation to the nitrogen metabolism in the glutamic acid fermentation is discussed. The biotin deficiency brought about the increase in the formation of glutamate and the decrease in the utilization of glutamate. 3. Not only the excretion of glutamate but also that of the other amino acids increased under the deficiency of biotin. 4. The biotin deficient cells contained less intracellular free amino acids than the biotin rich cells. 5. The compositions of intracellular bound amino acids of the biotin rich cells and the biotin deficient cells showed a close resemblance except some amino acids. 6. The contents of some of the intracellular bound amino acids changed appreciably with the biotin levels in the growth media. The contents of proline, methionine, tyrosine, lysine, and histidine decreased on lowering the biotin level in the growth medium. This may provide a possible explanation both for the growth regulation and the glutamate accumulation by M. glutamicus under the deficiency of biotin.
The mode of response of a B12-requiring organism, Lactobacills delbrueckii No. 1 to vitamin B12 is analyzed. This organism requires 500 to 600 molecules of B12 per cell for the normal cell multiplication. If B12 is present in excess in a surrounding medium, the cell of this organism has an ability to take up and preserve as much as 8×104 molecules of B12 for the subsequent growth. On the other hand, when B12 is deficient in a culture medium, cells elongate abnormally according to the degree of deficiency up to 300 to 500μ in length. In such cells, the number of B12 molecules retaining per unit cell length (3μ) becomes only 5 to 6. These distinctive features are found only in the B12-requiring Lactobacillus and are discussed from the view of the regulation of cell growth.
A yellow, gram-negative, non-sporeforming aerobic bacterium capable of utilizing oxalate as the sole source of carbon for growth was isolated from garden soil, for which the name, Bacterium oxalophilum, Takamiya et Kaneda is proposed. Among a number of organic compounds investigated, oxalate was found to be the only compound which permits rapid growth. No growth factor is required. Fatty Acids such as acetic, propionic, and butyric, at a concentration of M/30, strongly inhibit the growth of this organism in the oxalate medium. The growth was also strongly inhibited by monoiodoacetic acid, but not markedly by such poisons as NaF, arsenate and arsenite. This organism is extremely aerophilic, the growth taking place only on the surface of a solid medium or within a limited depth below the surface of a liquid culture medium when no agitation is applied during incubation. The oxidation of oxalate by the bacterial cells was investigated. Approximately 0.25 mole of oxygen is consumed and 1.75 moles of CO2 are evolved per mole of oxalic acid consumed. The possible role of this organism in the breakdown of oxalate in the soil is discussed.
The cell division of the fission yeast, Schizosaccharomyces pombe, was synchronized by the preincubation of cells at a high cell-density (1×109 cells per ml) for about one generation time followed by the dilution of the cell suspension by 100 times with a fresh medium. During the preincubation at the high cell density, glucose in culture medium was rapidly exhausted and the total nitrogen decreased corresponding to an increase in cellular nitrogen, while only a slight increase in cell number occurred initially. In the course of the crowded culture, the content of nucleic acid, mainly RNA, increased definitely at the expense of intracellular acid-soluble phosphorus compounds, while the amount of polyphosphate and DNA remained unchanged. In connection with these observations, the phasing mechanism of cellular age by the present method is discussed. During the course of synchronized culture, synthesis of RNA seemed to proceed very actively in the earlier phase of a cell cycle and that of DNA in the later stage just before the cell division, whereas the amount of protein increased almost linearly throughout the whole cycle.
The life cycles of three strains of Schizosaccharomyces were observed microscopically. Among them, conjugation of two ascospores, that of ascospore with vegetative cell, and spore formation in vegetative diploid cells produced from zygotes are described in detail.