Phosphatase activity was found to be applicable as a criterion for the differentiation of Mycoplasma salivarium and Mycoplasma orale, predominant constituents of oral mycoplasmal flora. Therefore, a simple procedure for the phosphatase activity assay was established as a screening test for the differentiation of oral mycoplasmas.
Aminopeptidase activity was demonstrated in Mycoplasma salivarium (ATCC 23064) cells disrupted by sonic vibrations and lyophilized (crude enzymes), and weak endopeptidase or carboxypeptidase activity was also suggested. The crude enzymes were suspended in 0.1 M borate buffer, pH 8.0, containing 0.5% (w/v) sodium deoxycholate, and then the suspensions were centrifuged at 100,000 g for 2 h. Thus separated, the supernatants were applied to a column of Sephacryl S-300. As a result, aminopeptidase activity was separated from caseinolytic activity, which had already been demonstrated in this organism. The aminopeptidase activity was inhibited by o-phenanthroline and stimulated by Mn2+, and the enzyme exhibited a strong affinity for leucine and arginine. On the other hand, the caseinolytic activity was inhibited considerably by o-phenanthroline and Ni2+ and slightly by diisopropyl fluorophosphate and Co2+. The caseinolytic activity was therefore believed to be due mainly to metalloproteinases and partly to serine proteinases.
The possibility of criticality of fuel debris in a form of uranium dioxide (UO 2 )-concrete mixture is evaluated by calculating the infinite multiplication factor (k ? ) for a study of criticality control on the fuel debris generated through the molten core concrete interaction in a severe accident of a light water reactor. The infinite multiplication factor can be greater than unity, which means that handling of the mixture is subject to criticality control. This paper shows that concrete provides efficient neutron moderation and points out the necessity of further investigations on the criticality of UO 2 -concrete system for actual handling of fuel debris.
Veillonellophage N2 prevented from adsorbing to Veillonella rodentium ATCC 17743 cells treated with polymyxin B, and also to lipopolysaccharides (LPSs) of the host cells treated with antibiotics. Therefore, these results indicate that receptor to phage N2 is cell wall LPSs. The LPSs of V. rodentium ATCC 17743 cells as receptor were characterized. Lipid A and total carbohydrate accounted for approximately 40% of the weight of the lipopolysaccharide complex. Heptose and 2-keto-3-deoxyoctonate were also present. Amino compounds included glucosamine, galactosamine, and glycine.
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