- Volume 17, Issue 3, 1957

SUMMARY: Several metabolite analogues have been tested for their effect on the growth of Bacillus anthracis and its ability to synthesize toxin and capsular material during the terminal bacteraemic stage of anthrax in the guinea pig. 8-Azaguanine, 8-azaxanthine and to a lesser degree, ethionine, α-amino-n-butyric acid andp-fluoro-phenylalanine inhibited the in vivo growth of B. anthracis, whilst 2-thiouracil and pyridine 3-sulphonic acid selectively inhibited toxin production. Inhibition of capsule formation was at no time convincingly demonstrated. The annulment of these inhibitions by mixture of the analogues with appropriate metabolites gives evidence that hypoxanthine, adenine, methionine, alanine, phenylalanine and tryptophan are involved in growth in vivo and pyrimidines and nicotinamide in toxin synthesis.

SUMMARY: A brief review of group G streptococci and their typing is given with particular reference to canine strains. Two of the Australian type strains of Simmons & Keogh (1940) were found to be in the group phase and useless for comparative purposes. Four types Kennett, Maxie, Airedale and R 51/755 were clearly defined in addition to the Australian types Harrison and Cuthell by reciprocal absorption tests using slide agglutination. Fifty-four other strains of which 35 were of animal and 19 of human origin were examined for type. Of the 38 strains from animal sources, 33 belonged to one of the two types Kennett or Maxie, strains of which came exclusively from animal sources. Six of the human strains and one of the animal ones were untyped.

Type R 51/755 which had been found previously by Maxted (1949) to possess the M28 antigen owed its type-specificity entirely to this antigen and this was not found to be present in any of the other types.

The substances responsible for type-specificity in types Kennett, Maxie, and Airedale differed from those of types Harrison and Cuthell and like that of type R 51/755 appeared to be protein in nature. The type-specific substances of types Airedale and Maxie had exactly the same characters as the M28 antigen in being sensitive to peptic but resistant to tryptic digestion. The protein antigen of type Kennett differed from the other three protein type-specific substances in showing only moderate resistance to tryptic digestion.

SUMMARY: Colonies of Rhizopus sexualis (Smith) Callen on 1 % (w/v) malt agar at 20° show the first stages in conjugation approximately 40 hr. after inoculation and the first mature zygospores after a further 32–34 hr. Transfer to 5–10° prevents the initiation of conjugation and inhibits the further development of the majority of pairings in which the gametangia are not fully delimited at the time of transfer. Fully delimited gametangia continue to develop and to produce mature zygospores at the low temperature. This effect is almost entirely independent of the composition and pH value of the medium. Sporangia are produced in greater numbers at the low temperature than at 20°. The effect of low temperature on formation of zygospores of Mucor hiemalis, Zygorrhynchus macrocarpus and Z. moelleri is essentially similar to that with R. sexualis, but Phycomyces blakesleeanus shows only slight inhibition at 5° and none at 7° or over. The significance of the inhibitory effect is discussed.