From a wild type strain Challis of the group H streptococcus, greening (Challis α) and β-hemolytic (Challis β) colonies were isolated on horse blood agar. Both colonies formed greening on sheep blood agar, and no significant differences were found in their biological, serological and chemieal analyses. They, however, showed clear differences on the transformability. Transformability, the producihility of competence-provoking factor (CPF) and competency which have been reported on the Challis strain were all found in Challis β strain. On the other hand, Challis α strain did not produce antibiotic-resistant transformants with the addition of CPF, and could not produce CPF even when the cells were cultured under various conditions of incubation or treated with lysozyme or detergents. The transformabilities of antibiotic-resistant mutants obtained from the Challis β strain were lower than those of the original Challis β strain, as pointed out by other investigators, while the Challis α strain became transformable on antibiotic resistance only when it acquired streptomycin resistance.In the Challis β strain and the antibiotic-resistant mutants of Challis α strain, the separate markers of streptomycin, penicillin, tetracycline, mitomycin C, as well as the combinations of these markers were found to be transformed at the highest rate in the strains having transformation of streptomycin resistance. The findings are discussed with respect to incorporation of deoxyribonucleic acid into recipient cells and to the reports of other workers.

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Two types of hemolysis, α and β were formed by group H streptococcus wild type strain Challis on horse blood agar, and both of the hemolytic markers could be transformed in each. α-Hemolysis-acquired transformants lost the competence-provoking factor producibility (CPF^-). When DNAs, obtained from strains Challis α, dihydrostreptomycin sulfate-resistant Challis α, and Wicky, were used CPF^- transformants appeared in high frequencies. DNAs from incompetent β cells grown in FT3 medium for 6hr or in heated ET3 medium for 2hr also transferred the CPF^-. CPF producibility (CPF⁺) was transformed with DNA from competent Challis β, while it was not transformed to Challis β with DNA from Wicky cells in competent and incompetent phases. Among β transformants obtained there were (1) those having CPF⁺ and competency, (2) those having competency but CPF^-, and also (3) those defective in both. Based upon these results, the transformability is discussed regarding close relation to DNA receptor site or CPF attachment and also on the probable transfer of itself by transforming DNA.

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Seventy-seven out of eighty-one group D streptococcal strains isolated from humans and animals were found to produce bacteriocins that were active on other streptococcal strains of gorup A and D, but inactive on their own cells. On the bases of the spectra of indicator strains, and the sensitivities to heat, chloroform, and trypsin, seven types of bacteriocins were classified. Streptococcus faecalis var. liquefaciens strain 4532 or strain A (liq-A) was UV-irradiated, and mutants which lost bacteriocinas well as the β-hemolysin-forming activities (Bact^-. Hem^-) were obtained. Cells of the type I bacteriocin producer (SM^r. TC^r. Bact-I⁺. Hem⁺) and nonproducer 2025 (PC^r. Bact-I^-. Hem^-), both belonging to S. faecalis var. liquefaciens, were mixed and incubated in broth. Recombinants (PC^r. SM^s. TC^s. Bact-I⁺. Hem⁺) were obtained at a high frequency (5.8% preinoculum size of PC^r. Bact-I-. Hem-), and the character was stable for at least ten transfers. In the mixed culture, a marked decrease in the recipient 2025 cell number was observed. The occurrence of recombinants was not inhibited by deoxyribonuclease. A cell-free filtrate of Bact⁺. Hem⁺ cells mixed with Bact^-. Hem^-cells did not cause a mutation of the latter combined characters. The transfer of a genetic marker is discussed as an event of the cell-to-cell contact.

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The role of complement in ingestion of nonencapsulated virulent group A streptococci by mouse peritoneal phagocytic cells was studied in vitro in the presence of type-specific IgG or IgM anti-M antibody. Type-specific IgG anti-M antibody significantly enhanced the phagocytosis, whereas IgM antibody was less effective in opsonization of the virulent group A streptococci. The extent of phagocytosis of streptococci sensitized with IgG or IgM anti-M antibody was not influenced by the presence of complement. These results suggested that complement was not an essential factor for efficient phagocytosis of virulent group A streptococci.

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A study was made to characterize the active substance for the extraordinarily strong adjuvant effect of the capsular polysaccharide of Klebsiella pneumoniae (CPS-K) type 1 Kasuya strain. CPS-K was fractionated into acidic and neutral CPS-K by the addition of cetyl-pyridinium chloride. Neutral CPS-K exhibited an extremely strong adjuvant effect. The active substance in neutral CPS-K was precipitable when mixed with a rabbit homologous antiserum. The neutral CPS-K antigen was serologically distinct from the O antigen and from the acidic CPS-K which was the type-specific capsular antigen. Among preparations of neutral CPS-K from eight different strains of K. pneumoniae tested, the preparation from only one strain (MH-2) exhibited a strong adjuvant effect comparable to that of the neutral CPS-K from the Kasuya strain. The neutral CPS-Ks from Kasuya and MH-2 strains were antigenically identical. This antigen was not found in all preparations of neutral CPS-Ks obtained from seven different strains. Preparations of acidic CPS-Ks from all strains of K. pneumoniae tested with various serologic types including Kasuya and MH-2 strains were found to exhibit only weak adjuvant effects. The active substance (neutral CPS-K antigen from Kasuya strain) was shown to form a single peak upon analyses by gel filtration (Sephadex G-100) and ultracentrifugation. Sedimentation coefficient of the substance was approximately 20S at a concentration of 5mg per ml in 0.1M NaCl. The active substance finally purified by gel filtration contained 65% sugars (as glucose equivalents), 6.8%, hexuronic acids, 2.6% hexosamine, 2.3% proteins, and very small amounts of lipids.

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A temperate phage, phage PS20, which originated in a lysogenic strain of Serratia marcescens was established to be able to transduce various auxotrophic markers in S. marcescens strains at an equal frequency which ranged from 10^-6 to 10^-7 per infected cell. Electron microscopic observations show that phage PS20 has a head (5.50A) hexagonal in outline and a tail (1000A×150A) with a contractile sheath which is attached to the head.

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Dimethyl sulfoxide (DMSO), administered intraperitoneally (i. p.) immediately before bacterial challenge, shortened the survival time of mice infected i. p. with a lethal dose of Salmonella enteritidis NUB 1 (virulent strain) and increased the mortality rate for mice infected i. p. with various bacterial strains showing low virulence for mice, such as S. enteritidis NUB 31 (avirulent strain), Pseudomouas aeruginosa, Klebsiella pneumoniae and Streptococcus pyogenes. It was revealed that DMSO enhanced multiplication of S, enteritidis NUB 1 or facilitated the survival of S. enteritidis NUB 31 in the bodies of mice. At 30hr after infection with S. enteritidis NUB 1 or NUB 31, most of the viable bacteria contained in the peritoneal fluid were recovered from cells in mice treated with DMSO as well as in untreated mice. There was no evidence that DMSO exerted any direct effect on microorganisms to stimulate in vitro growth or to enhance their virulence for mice. Ingestion by phagocytes of S. enteritidis NUB 1 injected i. p. or intravenously was not inhibited by DMSO. Although DMSO caused a transient decrease in the number of peritoneal macrophages, the enhancing effect of DMSO on infection did not appear to be solely due to a decrease of peritoneal macrophages. The effect of DMSO was highest when it was administered within one hour before or simultaneously with the bacterial challenge. The acceleration of deaths of mice infected with S. enteritidis NUB 1 by DMSO was also observed when the two agents were given orally.

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The UV sensitive bacterial mutants (abbreviated ms mutant) were isolated after N-methyl-N'-nitro-N-nitrosoguanidine (NG) mutagenesis. The ms mutants were found to be Her⁺, Rec⁺ and sensitive to UV and NG. The significance of the ms mutants was inability to support the multiplication of several mutant phages of P22 which were also isolated by NG mutagenesis. These characters of ms mutants were caused by a single point mutation. Some of the mutant phages unable to grow in ms host were also unable to grow in recA hosts and determined to be erf mutants. The remaining phages were classified in two groups, One group of mutants formed minute plaques on wild type host and fell in the same complementation group (x mutation) and the other formed larger plaques than wild type plaques and belonged to an another complementation group (y mutation). These newly found two genes were essentially involved in the replication of viable P22 DNA. Of the three mutants. x and erf were moderately sensitive to UV irradiation in comparison with y and wild type. Study of lysis patterns showed that the y or erf infected ms culture lysed despite their inability of forming viable progenies, whereas, the x infected ms culture did not lysed. The new x and y genes were both mapped in the early gene segment of P22 chromosome, on the left side of erf gene and between c₃ and c₂ genes, respectively. Based on these findings the contribution or substitution of the bacterial functions to the replication of bacteriophage was discussed.

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The influence of cyclophosphamide (Cy) on the establishment and duration of the intestinal resistance against enteric infection with a mouse adenovirus, strain K87, was examined in inbred mice, strain DK1. When Cy (40mg/kg/day) was administered to mice for 17 days from the time of virus challenge, a clear prolongation of viral growth and a delayed appearance of neutralizing (NT) antibody in the intestinal wall as well as in the serum were observed. When Cy (40mg/kg/day, for 14 days) was administered after cessation of viral growth (4 to 6 weeks after virus challenge) and part of the mice were rechallenged with the virus, titers of NT antibody and immunoglobulins became significantly lower than those in control mice not treated with Cy, and regrowth of the virus was observed in eight out of twenty-five Cy-treated mice, regardless of the presence or absence of rechallenge. In this experiment, antibody titers in the intestinal contents of eight virus-positive mice were significantly lower than those of the remaining seventeen virus-negative mice. The time when the decrease of intestinal NT antibody was maximum coincided with the time of the maximal frequency of viral regrowth. It was discussed that these facts might present an evidence to support the idea that the intestinal resistance was acquired through local NT antibody belonging to IgA in the intestinal tract.

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Chemical properties and compositions of slimes produced by two Pseudomonas aeruginosa strains of different colonial types were investigated. The main component of the slime from strain IFO 3445 was found to be DNA, contaminated with small amounts of protein. On the other hand, the slime from a mucoid-type strain No. 24 was an alginate-like substance consisting of mannuronic and glucuronic acids, and contained traces of protein and nucleic acid. Slimes from twenty clinical isolates of P. aeruginosa were investigated for their chemical compositions. Slimes from eighteen strains consisted of DNA, while, two strains of a mucoid-type produced slimes composed of polyuronic acid.

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