Isolation of bacteriophage-like particles from uninduced Clostridium tetani cultures

The isolation of hexagonal-headed, tailless, bacteriophage-like particles from uninduced cultures of Clostridium tetani is described. Clear, round, 1--3 mm diameter plaques were noted on Clostrisel agar plates, which were overlaid with soft agar inoculated with 7--14 day broth cultures. Particles were detected by transmission electron microscopy from broth cultures seeded with scrapings from the plaques. Both electron dense and electron lucent heads were noted. An electron dense head was observed attached to the surface of a dividing bacterium.

Differentiation of pathogenic, gram-negative, bacterial genera in the presence of beta-2-thienylalanine

Described in a fast screening assay for aid in the differentiation of bacterial genera. Salmonella is separated from Escherichia and Shigella, as a generic group on the basis of an inhibition assay incorporating beta-2-thienylalanine, and using a defined medium. The assay is also usable for confirmation of taxonomic differences between genera. The inhibition reaction, readable as an 'all-or-none' phenomenon, follows a dose-response relationship for cultures affected by beta-2-thienylalanine, and is unaffected by the growth phase of the culture.