SUMMARYStrains of lactobacilli were examined for lysogeny after treatment with mitomycin C. Forty strains belonging to 7 species out of 148 strains of 15 species were lysed by mitomycin C. Lysis was strongly dependent upon the concentration of mitomycin C, temperature and the age of the cultures.Phage-like particles were observed in 3 I out of 40 lysates by electron microscopy. Particles from ten lysates -four from Lactobacillus casei B, five from L. casei C and one from L. acidophilus -produced plaques when plated on suitable indicator strains and were thus considered to be active phages. The remaining 21 lysates that contained phage-like particles failed to produce plaques but four of them inhibited the growth of other lactobacilli. It was concluded that the particles in these lysates were defective phages.Activities, shapes, dimensions and serological properties of the newly induced phage-like particles were also studied.

Antigenic analyses of Lactobacillus bulgaricus, Lactobacillus lactis, Lactobacillus brevis and Lactobacillus buchneri were carried out by double immunodiffusion in agar. Antigens were extracted from whole cells and cell wall preparations with cold trichloroacetic acid. Most strains of the four species possessed antigen 9 in their cell walls. Another antigen, antigen 10, was found in the cell walls of all the strains of L. brevis and L. buchneri, and in some strains of L. lactis, but not in L. bulgaricus. Fractionation of the antigens was attempted using the cell wall extracts of L. lactis L‐10 with only antigen 9 and of L. brevis X‐1 with both antigens 9 and 10. The partially purified fractions of antigen 9 and of the complex of antigens 9 and 10 were obtained by zone electrophoresis. However, antigen 10 from the complex could not be separated by the same method or gel filtration on Sephadex G‐100 since the two antigens 9 and 10 of the complex always behaved together. The fraction of antigen 9 consisted almost entirely of glycerol and glucose as sugar components, the molar ratio being 2:1. The complex of antigens 9 and 10 also consisted of the same sugars, and the molar ratio of glycerol: glucose was 4:1. Inhibition tests indicated that the immunodominant component of antigen 9 was α‐methylglucoside (glucose), and most probably the determinant is a glucosylated glycerol teichoic acid. It was considered that the determinant of antigen 10 is a glycerol teichoic acid although glucosamine and galactosamine inhibited effectively the reaction between antigen 10 and its antibody.

Antigenic analyses of five species of the genus Pichia were carried out for taxonomic study by the slide agglutination method using monospecific and absorbed antisera and the agglutinin absorption technique. Comparative studies were also performed with a few strains of each of the same species and their classifications are discussed with respect to the antigenic structures and the patterns of proton magnetic resonance (PMR) spectra of their cell wall polysaccharides. Pichia delftensis and Pichia zaruensis possessed thermostable antigens 1, 2, 5 and 11, and the former had also thermolabile antigen m. Both species were closely related to Candida krusei. Pichia toletana possessed thermostable antigens 1, 2, 5, 11, 17 and 49. Pichia bovis contained thermostable antigens 1, 2, 14, 15, 16, 20 and 21, and it was related to most species of the genus Hansenula, although assimilation of potassium nitrate was negative. Finally, Pichia etchellsii possessed thermostable antigens 1, 2, 3, 4, 9 and 14, and was closely related to Pichia vini. Patterns of PMR spectra of mannans of these species also supported their serological relationships.Therefore, P. delftensis, P. zaruensis and P. etchellsii are considered to be the synonyms of Pichia fluxuum, Pichia dispora and P. vini respectively, although P. toletana and P. bovis are independent species.