Effect of the method of agitation on the accumulation of protective antigen in cultures of Bacillus anthracis.
Accumulation of protective antigen was essentially independent of culture volume, provided the organisms were kept in suspension by stirring. Agitation by orbited shaking was unsatisfactory.
Studies on Immunity in Anthrax XII. Requirement for Phosphate for Elaboration of Protective Antigen and Its Partial Replacement by Charcoal
Retention of protective antigen on columns of diethylaminoethyl cellulose was inhibited by the 0.01 m phosphate salts in the standard growth medium. Reduction in the concentration of phosphate to 0.001 m allowed satisfactory retention of antigen on diethylaminoethyl cellulose but decreased significantly the elaboration of antigen during growth of the cultures. Growth remained normal at phosphate concentrations as low as 0.0001 m. Inhibition of antigen elaboration in media containing reduced concentrations of phosphate was overcome by addition of 0.006% (w/v) charcoal. It is suggested that antigen elaboration, like encapsulation of virulent strains, is stimulated in the presence of an adsorbent. However, a nonencapsulated strain derived from an F mutant exhibited the same requirement for an adsorbent as nonencapsulated strains derived from the parent strain.
Studies on immunity in anthrax. II. In vitro elaboration of protective antigen by non-proteolytic mutants of Bacillus anthracis.
Non-proteolytic mutants were isolated from the Vollum strain of B. anthracis following ultraviolet treatment. The mutants were virulent for rabbits and mice and their non-proteolytic character was stable in culture and on serial passage in rabbits. The mutants produced protective antigen under suitable conditions of cultivation in vitro , and allowed longer incubation of the cultures without destruction of the protective antigen than did the parent strain. The meaning of the results is discussed.