1) The fluorescent substance produced by Pseudomonas aeruginosa was studied using strains which possess a charcteristic pigment-producing ability, strains No. 134, 145 and 117.
2) The Fluorescence I production of strain No. 134 is rapid and pronounced.
The effect of pH on the yellow-green portion of the Fluorescence I of this strain was studied and the following results were obserbed:
i) A reversible change in the tone of fluorescence takes place between pH 5.0 and pH 10.0. The color changes from blue to yellow-green at about pH 7.5 with a clear demarcation.
ii) The absorption spectrum of the substance shows a peak at 400mμ, and a characteristic wave length shows a peak at 460mμ. A change is noted in the absorption spectrum and characteristic wave length at about pH 5.0-4.0 when the tone of the fluorescence changes from colorless to orange.
3) The Fluorescence I fraction obtained by gel filtration from the culture filtrate of the three strains grown on the glutamic acid medium was examined paper-electrophoretically and the following results were obtained:
i) Four fluorescent spots appear on the filter paper. The spots were arbitrarily called α, β, γ and δ from the negative pole side. Strain 117 shows α and β and strains 134 and 145 shows β, γ and δ
ii) These spots appear in order from the negative pole side with time of cultivation regardless of the strain.

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The phage ε_34-1 was isolated from the stock solution of ε₃₄ stored in a frozen state. The phage mutant ε_34-1 is indistinguishable from the original phage ε₃₄ by plaque morphology, immunity-conferring function, serum neutralization, ultraviolet inducibility, heat stability, and transducing ability of R factor and a chromosomal marker (SM^r) in Salmonella.

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Three series of samples were prepared from Mycobacterium smegmatis Jucho and stored at-20C; (a) ³⁵S-labeled cells in 10% glycerol (intracellular irradiation with incorporated ³⁵S); (b) non-radioactive cells in 10% glycerol containing 10μc/ml ³⁵S (extracellar irradiation with ³⁵S); and (c) non-radioactive cells in 10% glycerol (control). Viable numbers and mutation frequency to isoniazid resistance were determined until the 84th day storage period. Conclusions from the above experiments are as follows:
(1) Bacterial cells maintained their viability up to 84 days of storage, when frozen in 10% glycerol containing no radioisotope.
(2) Bacterial cells irradiated with extracellular ³⁵S maintained their viability or decreased their viable numbers only slightly even after 84 days of irradiation period.
(3) Bacterial cells with incorporated ³⁵S lost their viability at a faster rate. It is suggested that this effect is due to the transmutation of ³⁵S to ³⁵Cl in bacterial protein molecules.
(4) As far as the observation from the technique of the present study with some experimental errors was concerned, no significant increase in mutation frequency could be detected in both the samples irradiated with incorporated ³⁵S and with extracellular ³⁵S.

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Seven new O antigenic groups and two new H antigens of the Hafnia group have been designated O62 to O68 and H33 to H34, respectively. Hafnia cultures with these new O and/or H antigens were divisible into 11 serotypes.
Seven new serotypes of the Hafnia group, belonging to already established O antigenic groups, have been reported because of the unknown combinations of their O and H antigens.

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A new serotype of Escherichia coli, possessing the identical O antigens to those of Shigella flexneri 2b and its serological variant, which has the identical O antigens with Sh. flexneri variant X, were described.
The basic feature of the variation was a sort of loss in their O antigens which is accompanied by some qualitative changes in factors of their O antigens. This was considered to be quite similar to the form variation frequently seen in Sh. flexneri cultures.
An important role of this variation in the serology of E. coli has been discussed.

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It has been shown that the sensitivity of Staphylococeus aureus to phenolic inhibitors can be influenced by the presence of gram-negative bacteria in the environment. In some instances, the presence of Salmonella schottmuelleri, Proteus mirabilis or Aerobacter aerogenes can increase the resistance of staphylococci to these inhibitors while in other cases these organisms can make Staph. aureus more sensitive to the compounds.

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