Using a crystalline lipase isolated from Aspergillus niger culture, Ca ion effect on various actions of the enzyme was examined. Using olive oil as the substrate for hydrolysis, Ca ion clearly enhanced the enzyme activity, whereas Ca ion exhibited an inhibitory effect on the hydrolytic action on triacetin. The esterifying activity of this enzyme on oleic acid was also inhibited by Ca ion. These findings together with other observations suggested that the formation of calcium salts of fatty acids produced from olive oil seemed to favor the physical conditions of the reaction mixture by improving the interface relationship between the oil substrate and water.
Fifty strains of acetic acid bacteria including closely related strains were taxonomically studied. Except for five brown pigment-producing strains, they were appropriately divided into two separate genera Gluconobacter and Acetobacter mainly in accordance with the flagellation and the oxidative behavior towards acetate and lactate. Thus the differentiation of acetic acid bacteria into two separate genera Gluconobacter and Acetobacter which was firstly proposed by ASAI was again verified. Species characterization within each genus of acetic acid bacteria was discussed and considered to be unreliable. An amendment was added to the previous publication concerning the flagellation of brown pigment-producing three strains, i, e., G. liquefaeiens G-1 (IAM 1834), G. melanogenus AC-8 (IAM 1835) and G. melanogenus U-4 (IAM 1836). They were confirmed to be peritrichous, not polar, and therefore were excluded from genus Gluconobacter. A remarkable mutation transforming from non-acetate oxidizing strain into acetate oxidizing one during the long periods of preservation in the laboratory was presented in the case with G. liquefaciens G-1 (IAM 1834). A new finding concerning the existence of polarly flagellated, . acetate-and lactate-oxidizing brown pigment-producing strains was also presented. Accordingly we have at present two different types of brown pigment-producing and acetate- and lactate-oxidizing strains besides G. melanogenus (Beijerinck) Asai (Syn. A, melanogenus Beijerinck); one is characterized by peritrichous flagellation and the other is characterized by polar flagellation. The generic situation of those organisms was discussed and was decided temporarily as "intermediate" strains neither assignable to genus Gluconobacter nor to genus Acetobacter. Phylogenetic relationship of genera Gluconobacter and Acetobacter with reference to the "intermediate" strains was also discussed.
1) On the basis of the additivity of magnetic susceptibility, a new method was presented for estimating the volume fraction of microbial cells in suspension. 2) Yeast cells were used for making a comparison between the magnetic volume fraction thus obtained and the morphological volume fraction. 3) The present method gives an estimate of the cell space surrounded by the cell membrane, thus making a basis for dielectric studies of cell suspensions.
An adenine auxotroph of glutamic acid-producing bacterium, Micrococcusglutamicus No. 534-348, accumulated 5′-inosinic acid in culture media. Inosine was scarcely detected although a small amount of hypoxanthine accumulated simultaneously. The growth of the mutant responded specifically to adenine and its derivatives. Adenine, adenosine, adenylic acid and adenosine triphosphate were effective in this order in supporting the growth of the mutant. High concentrations of adenine inhibited the accumulation of inosinic acid. Abundant accumulation of inosinic acid occurred in the media containing sufficient concentrations of biotin and suboptimal concentrations of adenine for the growth of the microorganism. Considerable accumulation of glutamic acid occurred by limiting the concentration of adenine, even at concentrations of biotin high enough to suppress the glutamic acid accumulation by the parent culture. Accumulation of inosinic acid progressed with the growth of the bacterium and further accumulation occurred even after the growth had essentially been completed.
The growth of a strain of the glutamic acid producing bacterium Micrococcus glutamicus remained at very low levels even when the incubation was continued for several days. The addition of both casamino acids and ferrichrome to the synthetic medium was necessary to increase the growth level of the bacterium. Ferrichrome could be replaced by the following compounds: ferrichrome A, hydroxyaspergillic acid, large amounts of ascorbic acid or araboascorbic acid, and large quantities of iron salts. Cysteine or cystine, histidine, leucine and any one of the aromatic amino acids were concluded to be most important amino acids. The mixture of these four amino acids could replace casamino acids.
By changing the size of air bubbles from about 8.8mm to 1.6mm, the effect of a surfactant on the value of liquid film coefficient of oxygen transfer was studied experimentally. With bubbles larger than 2mm up to the experimental limit of 8.8mm in size, no appreciable differences were observed related to the size of bubbles irrespective of the cases with and without the surfactant. An assumption that the increase of resistance to oxygen transfer in bubble aeration, in which the surfactant is involved was primarily due to the specific action of surfactant in calming the complicated motion of bubbles at the interface, was discussed with reference to the theoretical analyses which have already been made available from either the penetration theory or the boundary layer theory of mass transfer. If the size of the bubbles was reduced less than about 2mm in size, the increase of resistance to oxygen transfer in bubble aeration was appreciable enough in both cases with and without the surfactant.
Intact yeast and green algal cells were found to have high apparent dielectric constants of 2, 100 and 400. When a thin layer of low conductivity is assumed to be in the cell envelope, the dielectric behavior of cell suspensions can satisfactorily be interpreted in terms of MAXWELL-WAGNER's mechanism. The thin layer seems to correspond to the plasma membrane, having a membrane capacity of 1μF•cm-2. In analyzing the observed data on the impedance property of yeast cells in suspension, it was found necessary to take into consideration the presence of the cell wall as well as the plasma membrane. However, it was shown to be adequate to regard a cell as a homogeneous particle with a single thin layer of low conductivity located in the cell surface, provided that contributions from the cell wall are dealt with by adopting such a modified definition of volume fraction as to exclude the volume occupied by the cell wall.
Edited and published by : Applied Microbiology, Molecular and Cellular Biosciences Research Foundation/Center for Academic Publications Japan Produced and listed by : TERRAPUB, Center for Academic Publications Japan/Shobi Printing Co., Ltd. (-Vol.60,No12), Center for Academic Publications Japan/InternationalAcademic Printing Co., Ltd.(-Vol.54,No1)