THE INFLUENCE OF CERTAIN SALTS, AMINO ACIDS, SUGARS, AND PROTEINS ON THE STABILITY OF RICKETTSIAE

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Abstract
The survival of various strains of rickettsiae, all partially purified from infected yolk-sac material, was investigated by estimation of their infectivity for chick embryos, cotton rats, or mice, or by their toxicity for mice after incubation in various media for varying periods of time at 30-32[degree]C. The survival of 2 strains of R. prowazekii, one strain of R. mooseri. one strain of R. tsutsugamushi (orientalis). and one strain of Derma-centroxenus rickettsi is favored by the following factors: (1) the presence of 0.005 M-glutamate; (2)'' a pH close to 7; (3) a basal salt soln. high in K+ rather than one high in Na+; and (4) the presence of 0.1-1% serum albumin, bovine or human. For the preservation of viability during freezing and thawing a variety of substances may be used, but of those tested only sucrose and albumin will also favor survival of the rickettsiae at room temp. For this purpose sucrose may be used in concns. between 0.05 [image] and 0.22 [image]; albumin must be present in a concn. of 4-6%. A useful medium for the preservation of rickettsiae for several hrs. at room temp. or 0[degree]C, and during freezing and thawing is one containing sucrose, 0.218 [image]; KH2PO4, 0.0038 [image]; K2HPO4, 0.0072 [image]; and glutamate, 0.0049 [image]. It may be further improved by the addition of 1% serum albumin.
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