Modification of Combined Effect of Radiation and Sodium Chloride on Microorganisms by Chemical Agents during Irradiation

Effects of various chemical agents on the synergistic action of NaCl to the radiation inactivation of bacteria and yeast were studied. The remarkable modification of the radiation lethal effect by some reagents is considered to be a strong evidence for an indirect nature of NaCl synergistic action during irradiation. Most of these modification effects were restricted to the actions during irradiation, supporting the free radical hypothesis in which the short-life active species formed by radiation were considered to attack bacterial cells. Furthermore, pre-irradiation effects under various conditions suggest that the enhancement of radiation lethal effect by NaCl may involve the intracellular events.     

Incorporation of Glycine and Serine into Sporulating Cells of Bacillus subtilis

The changes during growth and sporulation in activities of cells of Bacillus subtilis to incorporate various amino acids were investigated with wild-type strain and its asporogenous mutant. In the case of wild type strain the uptake of valine, phenylalanine, and proline was largest during the logarithmic growth period. The uptake of these amino acids decreased rapidly during the early stationary phase. The uptake of valine and cysteine increased again to some extent just prior to the forespore stage. The uptake of glycine and serine, however, was largest at the forespore stage at which the formation of spore coat took place. From these observed phenomena it was assumed that the remarkable incorporation of glycine and serine into the wild type strain during sporulation was closely related to the formation of spore coat.     

Effect of Irradiation on Microorganisms in a Nuclear Reactor

The effects of irradiation in the JRR-1 (Japan Research Reactor No. 1, a homogeneous light water nuclear reactor; max. power, 50 KW) on microorganisms such as bacterial and fungal spores and yeast cells were investigated in comparison with those of ⁶⁰Co gamma radiation. As far as the lethal effect was concerned the dose rate of radiation in the experimental hole No. 16 of the JRR-1 was equivalent to 3.0×l0⁶~3.4×l0⁶ r/hr with ⁶⁰Co gamma radiation, and a ratio of the neutron effect to the gamma radiation effect on microorganisms in this hole was estimated to be approximately 3~5.4. The results different from those with gamma radiation were obtained in experiments such as post-NaCl treatment and spore germination. The considerable contribution of fast neutrons to the total biological effect of neutrons, in comparison with the thermal neutron effect, could be presumed from the microbiological experiments with the help of physical and chemical data. Morphological changes in post-irradiation growth were observed by means of phase contrast microscopy. No specific aftereffect was found.     

Studies on γ-Radiolysis of Sulfur Containing Amino Acids

In connection with flavor deterioration accompanied by food irradiation, the effect of γ-irradiation on sulfoxide amino acids in air free aqueous system was investigated. The major radiolysis products from S-n-propyl-l-cysteine sulfoxide (PCSO) were alanine, cysteic acid, dipropyl disulfide, etc., and from S-allyl-l-cysteine sulfoxide (ACSO) were S-allyl-l-cysteine, cystine, cysteic acid, etc., which were isolated chromatographycally and identified by using IR and mass spectrometry. The sulfoxide in ACSO was more easily reduced to sulfide than that of in PCSO, and the bond of S-C (β-carbon in alanine moiety) in ACSO was difficult to cleave. These differences observed between PCSO and ACSO in the radiolysis products and their yields indicate that the radiolysis degradation is considerably influenced by the structure of alkyl group. From the experiments with N₂O or KBr addition during irradiation, principal roles of the active species in irradiated water in the degradation processes were partly elucidated.     

Mutagen Formation in the Reaction of Nitrite with the Food Components Analogous to Sorbic Acid

Mutagen formation by the reaction of sodium nitrite with some sorbic acid analogs was investigated by using the microbial mutagenicity tests (rec-assay and Ames test) together with chemical examination using TLC, and it became clear that the conjugated dienoic carbonyl structure is essential for mutagen formation by the reaction with nitrite By a large scale reaction of sodium nitrite with sorbic acid methyl ester, 5-nitro-2,4-hexadienoic acid methyl ester and ethylnitrohc acid were isolated and identified as the mam mutagens The results led to the assumption that a nitro group adjacent to the double bond is an important factor to develop mutagenicity     

The After Effect of Irradiated Halogenophenol Solutions on the Viability of Escherichia coli

Gamma irradiation has been found to induce a remarkable bactericidal activity in an aqueous soltion of p-bromophenol even at the non-toxic lower concentrations, but not in a crystalline form or under a frozen state. Effects of concentration of reagents, temperature, pH, radiation dose, oxygen and some additives during irradiation on the radiation induction of bactericidal activity in the p-bromophenol solution were investigated. The results suggest that the induced activity is attributable to some long-life products, formed as a result of radiolysis of p-bromophenol and in coupling with radiolysis of water. The processes of formation and destruction of such bactericidal factor(s) were considerably influenced by several conditions during irradiation. Based on the experimental results, relationship between radiolysis process and induction of bactericidal activity was discussed.     

A Novel Reaction of Sugars with Anion Radical of Carbon Dioxide Produced from Formate

Radiolysis of some monosaccharides (fructose, glucose and ribose) in air-free condition was markedly enhanced by the addition of formate at concentrations above 20 mm, while it was inhibited at concentrations below 20 mm. The following compounds were detected in the irradiated sugar solutions containing excess formate (100mm): 1-Deoxy-d-arabinohexulose (1, G=4.4) and 1,3- dideoxy-d-erythrohexulose (2, G= 1.3) from fructose; 2-deoxy-d-ribose (3, G=2.3) and 2-deoxyribitol (4, G =0.6) from ribose; and 2-deoxy-d-glucose (5, G=0.5) and 2-deoxy-d-glucitol (6, G=0.4) from glucose. A mechanism for radiolytic formation of the products was proposed, based on interaction of - formed from formate with sugars.     

Red Pigment Formation by the Reaction of Oxidized Ascorbic Acid and Protein in a Food Model System of Low Moisture Content

Ascorbic acid-protein mixtures of low moisture content stored for 2~3 days in aerobic conditions at 60°C produced a red coloration, which was shown to have resulted from an amino-carbonyl reaction of oxidized ascorbic acid (dehydroascorbic acid, DHA) by the facts that DHA-casein or ovalbumin systems yielded a rapid red coloration in low moisture conditions as well as in an ethanol suspension. Zein showed only a weak red coloration with DHA. An apparent decrease in the free amino group, as determined by the TNBS method, was observed to be associated in parallel with the red pigment formation. The electrophoretic pattern of ovalbumin changed significantly upon incubation with DHA, together with the formation of the red pigment. The red pigment extracted from a DHA-casein system showed an absorption spectrum, TLC Rf value, and hydrolyzed products (DHA and scorbamic acid) identical to those of 2,2′-nitrilo di-2(2)-deoxy-l-ascorbic acid mono ammonium salt, produced from DHA and amino acid. Formation of the red pigment was also observed in the reaction of DHA with N_α-acetyl lysine. These results indicate that the ε-amino group of lysine in protein can be attributed to the formation of a red pigment identical with NDA.     

Ionophorous Properties of SY-1 (20-Deoxysalinomycin) in Rat Liver Mitochondri

SY-1 (20-deoxysalinomycin), a monocarboxylic polyether antibiotic closely related to salinomycin, caused a rapid release of previously accumulated alkali metal cations by valinomycin or monazomycin in rat liver mitochondria, and simultaneously reversed swelling of mitochondria.

With a strict specificity for substrate and cation, SY-1 exhibited a property of inhibiting mitochondrial functions such as substrate oxidation, oxidative phosphorylation and ATP hydrolysis induced by valinomycin or monazomycin, In comparative study with salinomycin, SY-1 was found to be more effective on the mitochondrial functions than salinomycin.

On the basis of the results so far obtained, the inhibitory effect of SY-1 on mitochondria is interpreted as a result of interaction with essential cations, especially with K⁺, in mitochondria.     

Decomposition of Allyl Isothiocyanate in Aqueous Solution

Allyl isothiocyanate was gradually decomposed in aqueous solution to produce a garlic like odor. The decomposition of this isothiocyanate was not based on hydrolysis of R-NCS as in the case of p-hydroxybenzyl isothiocyanate, but the addition reaction on –N=C=S. Four substances formed with the decomposition of the isothiocyanate were isolated, and their chemical constitutions were clarified. Allyl isothiocyanate was decomposed to allyl allyldithiocarbamate (III), which was degradated to diallyl tetra- and penta-sulfide (II), and this poly-sulfide was further degradated to paraffin like hydrocarbon (I) and sulfur. Moreover, N,N′-diallylthiourea (IV) was produced by the addition reaction of allylamine, formed from the isothiocyanate by action of water, to residual isothiocyanate.