Using intact cells of Anabaena cylindrica as a test organism, the action spectra of light-induced nitrite reduction were determined under light-limiting conditions. It was found that the action spectrum of nitrite reduction is identical with that of photosynthesis (CO2-fixation), showing a single peak at 620mμ and a small shoulder at ca. 680mμ. When the cells were exposed simultaneously to two monochromatic light beams (e.g., 620mμ and 680mμ), there occurs a marked stimulation of nitrite reduction (EMERSON'S effect-like phenomenon). The action spectrum of this enhancement effect shows a peak at 620mμ when a light of 695mμ was used for background illumination and around 700mμ when a light of 623mμ was adopted. Under H2-atmosphere and in the presence of a sufficient amount of CMU, nitrite reduction was stimulated by lights around 700mμ as well as by lights around 620mμ. The former light was found to be about twice as effective as the latter. On the basis of these results, a brief discussion was made concerning the mechanism of light-induced nitrite reduction.
Pressure drop of air flow and collection efficiency of bacterial particles through plate filters made of polyvinyl alcohol were studied. A remarkably high collection efficiency with less pressure drop was obtained. The experimental results were compared with the performance of fibrous glass filter which is extensively employed in the fermentation industry. The comparison, with reference to the field data of the plate filter, predicts a possibility that the plate made of polyvinyl alcohol could be applied to the fermentation practice. If the fibrous air sterilization filter is replaced by the plate filter, the size of the current device will be reduced tremendously with the economy of construction as well as maintenance costs. However, the mechanism which accounts for the excellent performance of the plate filter is left open for further experimentation and theoretical consideration.
Using several strains of Rhodotorula, the stability of the requirement of thiamine and para-aminobenzoic acid was reexamined. Each of the tested organisms had been maintained on two different media. Besides, the tests were performed in comparison between two methods of incubation. It was found that the degree of requirement for thiamine and for its two pyrimidine and thiazole moieties considerably varied with cultural conditions, while that of para-aminobenzoic acid by some strains did not vary with conditions of preservation and incubation, indicating its essentiality in accordance with the previous results. Discussions were made on the taxonomic significance of the vitamin requirement for the genus Rhodotorula.
The sites of reduction of tetrazolium salts in cells of a strain of FusobacteriumPolymorphum was investigated by means of light microscopy and electron microscopy. The formazans of triphenyltetrazolium chloride were demonstrated to occur as relatively large crystal-shaped depositions in the cytoplasm. As these granules, usually a few in number, seemed to be formed secondarily by the intracellular aggregation of small granules primarily formed in the cytoplasm, it was almost impossible to localize the initial sites of TTC reduction in the cytoplasm. On the contrary, nitrobluetetrazolium formazans were proved to deposit very close to the cytoplasmic membrane and the intracytoplasmic membrane system. These observations strongly suggest that the site of oxidation-reduction activity may be associated with the cytoplasmic membrane and the intracytoplasmic membrane system which have recently been found in various Actinomycetes and Eubacteria.
Thirteen clones of RNA phages acting upon Escherichia coli (K-12 strain W2252) were isolated from sewage in Tokyo by the use of antiserum of a standard RNA phage MS-2. The properties of one of the isolates, phage β, were studied in detail. It was found that this phage gives two peaks, about 75 and 90 in the S values, upon analytical centrifugation, and arrests the formation of β-galactosidase at 25min after infection. The intracelluar mature phages begin to appear at the same time.
Seven strains of B. natto investigated were found to be all vulnerable to phage S-l, while five among them were able to transfer their genetic traits to B. subtilis by the phage. All strains, including the two which could not transduce, were able to transform the genetic markers in B. subtilis by the DNA. The transduction as well as the transformation from B. subtilis to B. natto was also successful. Based on these results, the geneticsimilarly between B. subtilis and B. natto was discussed.
The phosphorus metabolism of growing surface colonies of Aspergillus niger was investigated, 32P-Phosphate was found to be incorporated most actively at the growing margin, thereafter to be translocated, not recognizably laterally, but upwardly toward conidia through the conidia-forming apparatus. It was observed that with the progress of conidia formation the macromolecular phosphorus compounds (RNA, DNA and polyphosphate) in hyphae underwent active turnover. Evidence was presented showing that there are at least two sites of biosyntheses of P-containing macromolecules in a growing colony, one being located at the lower layer (substrate mycelia) and the other at the upper layer (aerial mycelia) of the mat. The bulk RNA's synthesized at different sites in the mat was shown to be different in their chemical nature. Based on these and other observations, it was inferred that the P- containing macromolecules synthesized in the upper layer would be translocated into conidia without being accompanied by their decomposition or transformation. Discussions were made on such views with reference to the cytochemical and electronmicroscopical observations made earlier of the mold colonies by the present authors and other workers.
The mycelial mat of Asperillus niger grown for 60hr on the cellophane-agar was briefly labeled with 35S-sulfate, and the change in specific activities of choline sulfate and sulfur-protein contained in the mat was followed during the course of its cultivation on the "cold" medium. From the characteristic pattern of the change in the specific activities, it was inferred that the biosyntheses of these S-compounds take place on, at least, two sites in the upper and lower layers of the mycelial mat. Proteins obtained from the upper layer was found to be richer in cyst(e)ine content than that from the lower layer. The cellular differentation of mold colonies during sporulation was discussed with reference to the specific nature of the chemical composition of conidia.
Using B. subtilis as material the effects of L-cysteine on the production of α-amylase, RNA and DNA synthesis, cell growth, amino acids incorporation into protein and some other metabolisms were investigated. The strongest inhibition was observed in the synthesis of RNA and, to a lesser extent, in DNA synthesis and α-amylase production. The effect was reversed by some factors contained in yeast extract.
Incorporation of 14CO2 into conidiospores of Aspergillus niger (strain 1617) was investigated under various cultural conditions. The conidia incubated in a complete germination medium incorporated 14CO2 very actively without any lag period. By using various media for incubation, it was found that the more favorable the medium for the germination, the more active was the 14CO2-incorporation. In the germinating conidia fed with 14CO2, a large amount of radioactivity was found in the protein fraction as well as in the acid-soluble fraction, in which ATP was revealed to be one of the major substances to be labeled within a short period. Quickly labeled were also nucleic acids, in which adenine, cytosine and uracil were strongly labeled, while thymine and guanine were less strongly, but definitely, labeled even at the onset of germination. Based on these observations as well as those made earlier of the phosphorus and alanine metabolisms of germinating conidia, inferences and discussions were made of the biochemical events occurring in the early phase of conidia germination.
STUDIES ON LIPASE
I. PURIFICATION AND CRYSTALLIZATION OF A LIPASE SECRETED BY ASPERGILLUS NIGER
A strain of Aspergillus niger selected by an extensive screening test was found to secrete a large amount of lipase when grown on the bran-Koji medium. The enzyme was purified from the water extract of bran-Koji by fractionations with ammonium sulfate and acetone, followed by acid treatment, acrinol precipitation and ion exchange chromatography. It was finally obtained in a crystalline form from a solution in acetone. Electrophoretic analysis showed that the crystalline enzyme was a single protein. Its activity did not decrease on exhaustive dialysis against water, suggesting the absence of a dialyzable co-factor. The crystalline enzyme hydrolyzes olive oil almost completely, whereas it does not attack methyl butyrate at all. The action of the enzyme upon olive oil has the optimum pH at about 5.6 and the optimum temperature at 25°. The enzyme was stable at the pH range between 2.2 and 6.8, and at pH 5.6 it could resist temperatures up to 50° for 15min.
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)