Taxonomic studies were carried out on 145 strains of Gram-negative methanol-utilizing bacteria, and they were divided into the following four major groups on the basis of morphological characteristics, assimilation of carbon compounds, cellular fatty acid composition, and coenzyme Q system. Bacteria of group 1 were polarly flagellated rods, and showed the presence of coenzyme Q8 and cellular fatty acid composition consisting of a large amount of C16:0 acid and C16:1 acid (Type A). The so-called "obligate methylotrophs" are included in this group. Bacteria of group 2 were polarly flagellated rods, and showed the presence of coenzyme Q10 and cellular fatty acid composition consisting of a large amount of C18:1 acid (Type B). Bacteria of group 3 belonged to the genus Microcyclus on the basis of morphological characteristics. They showed the presence of coenzyme Q10 and Type B of cellular fatty acid composition. Bacteria of group 4 belonged to the genus Hyphomicrobium on the basis of morphological characteristics. They showed the presence of coenzyme Q9 and Type B of cellular fatty acid composition. Bacteria of groups 1 and 2 differed from Pseudomonas in point of cellular fatty acid composition and coenzyme Q system. Taxonomic implication of cellular fatty acid composition was discussed from the viewpoint of the change in the composition according to cultural conditions.
Two forms of invertase, isolated from Fusarium oxysporum, were designated P-1 and P-2 enzymes according to their respective elution profiles on DEAE-cellulose column. P-1 was produced mainly at an early stage in the cell culture and P-2 was produced at a late stage and its production agreed with the appearance of microconidia. Mycelia separated from microconidia contained only P-1. Optimum pH, substrate specificity, and transferase activity of P-1 enzyme were somewhat different from those of P-2 enzyme. Invertase (M) secreted into the medium at a late stage in the culture showed similar properties to P-2 enzyme. All three enzymes contained carbohydrates and showed β-fructofuranosidase activity. P-1 and P-2 enzymes were both inhibited by Ca2+, Zn2+, and Cu2+ but not by Ni2+ and Co2+.
Superoxide dismutase has been characterized in normal and also in nitrofurantoin-resistant mutant strain of Vibrio el tor. An induction of this enzyme, which is noted in Vibrio el tor when grown under hyperbaric oxygen, is inhibited by nitrofurantoin. This induction of superoxide dismutase becomes insensitive to nitrofurantoin in Vibrio el tor after it acquires resistance towards the antibacterial agent. The lethal effect of superoxide radicals on Vibrio el tor is shown by both photo-chemically and enzymically generated superoxide radicals. Nitrofurantoin aggravated the lethal effect of superoxide radicals in normal as well as in nitrofurantoin-resistant mutant of the microorganism. Bovine superoxide dismutase preparation exhibited a protective effect on the enhanced lethality of superoxide radicals towards Vibrio el tor strains in the presence of nitrofurantoin. Superoxide dismutase could also inhibit the photochemical and enzymic activation of nitrofurantoin.
A comparative study was made on two forms of Candida parapsilosis. From the reciprocal absorption experiment of antiserum for heated cells of these yeasts, and gel diffusion precipitation of mannans, the two forms were assumed to possess a small amount of respectively specific antigens in addition to antigens common to both. Factor antiserum 24 prepared from antiserum for Saccharomyces rosei agglutinated C. parapsilosis form I but not form II, and is considered to be useful for clear-cut discrimination of the two forms. Proton magnetic resonance spectrum of mannans also demonstrated the difference of the two forms. Further, C. parapsilosis assimilated L-arabinose, did not excrete excess amount of riboflavin into synthetic media, and did not require thiamine. Since C. parapsilosis form II was found to correspond to the imperfect form of Lodderomyceselongisporus, these characteristics are useful for the discrimination of the imperfect form of L. elongisporus from C. parapsilosis.
In order to apply bioluminescence of luminous bacteria to industrial use, isolation of luminous bacteria from various sources was carried out on the basis of strong light intensity, and 18 strains were obtained. Eleven of these strains were identified as Photobacterium phosphoreum and seven as Vibrio fischeri. Maximum light intensities of these isolates were quite different among strains tested and two stock cultures of luminous bacteria supplied by the American Type Culture Collection had a very poor bioluminescence compared to the new isolates. Bioluminescent emission spectra from the two isolated strains were fairly different from each other, indicating the possibility of obtaining luminous bacteria which could emit light of different colors. While cultivation of some luminous bacteria was repeated several times in a liquid medium, decrease of light intensity was observed. By spreading the culture broth on an agar plate medium, three kinds of colonies were observed. They were quite different in the appearance of colonies and maximum light intensity. These results suggest that the occurrence of dim mutants in liquid cultures is disadvantageous for maintaining the light intensity constant and a strain which could be as stable as possible at this point should be used for industrial purpose.